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Pradeep J Nathan - One of the best experts on this subject based on the ideXlab platform.
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interaction of estrogen with central serotonergic mechanisms in human sensory processing loudness dependence of the Auditory Evoked Potential and mismatch negativity
Journal of Psychopharmacology, 2011Co-Authors: Valerie Guille, Rodney J Croft, Pradeep J Nathan, Andrea Gogos, Maarten Van Den BuuseAbstract:Estrogen may be involved in schizophrenia by inhibiting serotonin-1A (5-HT(1A)) receptor function. We examined the effects of estrogen pre-treatment on modulation of loudness dependence of the Auditory Evoked Potential (LDAEP) and mismatch negativity by the 5-HT(1A) receptor partial agonist, buspirone. Using a double-blind, placebo-controlled, repeated-measures design in healthy female volunteers, we observed that buspirone treatment significantly increased LDAEP slope. Estrogen increased LDAEP slope on its own, and a further LDAEP increase by buspirone was not seen after estrogen pre-treatment. Similar results were observed for mismatch negativity, where buspirone caused a small increase of latency, although not amplitude, after placebo but not estrogen pre-treatment, which enhanced mismatch negativity latency on its own. These results are in line with our previous findings on prepulse inhibition showing an inhibitory effect of estrogen on the action of buspirone. Taken together, these data suggest that estrogen may inhibit 5-HT(1A) receptor-mediated disruptions of Auditory processing.
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chronic modulation of serotonergic neurotransmission with sertraline attenuates the loudness dependence of the Auditory Evoked Potential in healthy participants
Psychopharmacology, 2011Co-Authors: Julian G Simmons, Pradeep J Nathan, Gregor Berger, Nicholas B AllenAbstract:Rationale The loudness dependence of the Auditory Evoked Potential (LDAEP) has been reported to be an effective non-invasive measure of central serotonergic neurotransmission. However, acute manipulations of the serotonergic system in humans and animals have yielded inconsistent findings.
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evidence for sex differences in the loudness dependence of the Auditory Evoked Potential in humans
Human Psychopharmacology-clinical and Experimental, 2011Co-Authors: Jessica Lee Oliva, Rodney J Croft, Pradeep J Nathan, Barry V Oneill, Sumie Leung, Julie C StoutAbstract:Objective: The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a marker of the serotonin system, although studies directly examining the relationship between acute changes in serotonin and the LDAEP have been inconsistent. Given the reported sex dichotomy in serotonin neurotransmission, this study examined if there are sex differences in the LDAEP. Methods: Data from 65 healthy participants from four independent studies were pooled, and their N1/P2 slopes were quantified. Results: Mean N1/P2 slopes for female participants were higher than those for male participants (p < 0.0001). Conclusion: These findings suggest that the LDAEP is modulated by sex Potentially because of differences in serotonergic neurotransmission, and these differences may account for some of the inconsistent findings linking serotonin function and LDAEP.
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the loudness dependence Auditory Evoked Potential is insensitive to acute changes in serotonergic and noradrenergic neurotransmission
Human Psychopharmacology-clinical and Experimental, 2010Co-Authors: Jessica Lee Oliva, Rodney J Croft, Luan K Phan, Pradeep J Nathan, Barry V Oneill, Sumie Leung, Julie C Stout, Joanne OkaneAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been proposed as an electrophysiological marker for assessing serotonergic function in vivo in humans, although accumulating evidence suggests that it is insensitive to acute changes in serotonergic neurotransmission. Very little is known about the sensitivity of the LDAEP to other neurotransmitter systems including the noradrenergic system. The current study examined the effects of noradrenergic modulation as well as serotonergic modulation on the LDAEP. Methods The study utilised a double-blind placebo-controlled design in which the LDAEP in 17 healthy males and females was tested following acute administration of each of citalopram (20 mg), reboxetine (4 mg) and placebo. Results Neither citalopram nor reboxetine modulated the LDAEP relative to placebo treatment (p > 0.05). Conclusion These findings suggest that the LDAEP is insensitive to acute changes in serotonergic or noradrenergic neurotransmission and thus is a poor pharmacodynamic marker of these systems. Copyright # 2010 John Wiley & Sons, Ltd.
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effects of selective and combined serotonin and dopamine depletion on the loudness dependence of the Auditory Evoked Potential ldaep in humans
Human Psychopharmacology-clinical and Experimental, 2008Co-Authors: Rodney J Croft, Luan K Phan, Pradeep J Nathan, Valerie Guille, Barry V Oneill, Sumie Leung, Kirsty Elizabeth ScholesAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a possible in vivo measure of central serotonin function. However, more recent studies suggest that the LDAEP may be modulated by multiple neuromodulatory systems in addition to the serotonergic system. Accordingly we further examined the effects of selective serotonin, dopamine and simultaneous serotonin and dopamine depletion on the LDAEP in healthy subjects. Methods The study employed a placebo-controlled, double-blind, cross over design. Fourteen subjects were tested under four acute treatment conditions: placebo (balanced amino acid drink), tryptophan (serotonin) depletion (ATD), tyrosine/phenylalanine (dopamine) depletion (ATPD) and combined tryptophan/tyrosine/phenylalanine (serotonin and dopamine) depletion (CMD). Testing was conducted 5.5 h post-depletion and changes in the amplitude of the N1/P2 at varying intensities (60, 70, 80, 90, 100 dB) were examined at CZ. Results Greater than 80% plasma precursor depletion was achieved across all conditions. Despite significant depletion of monoamine precursors, ATD, (p = 0.318), ATPD (p = 0.061) and CMD (p = 0.104) had no effects on the LDAEP (60–100 dB). Conclusion Acute serotonin and dopamine depletion did not modulate the LDAEP. This finding adds support to growing evidence that the LDAEP is insensitive to acute changes in serotonin and dopamine neurotransmission. Copyright © 2008 John Wiley & Sons, Ltd.
Rodney J Croft - One of the best experts on this subject based on the ideXlab platform.
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interaction of estrogen with central serotonergic mechanisms in human sensory processing loudness dependence of the Auditory Evoked Potential and mismatch negativity
Journal of Psychopharmacology, 2011Co-Authors: Valerie Guille, Rodney J Croft, Pradeep J Nathan, Andrea Gogos, Maarten Van Den BuuseAbstract:Estrogen may be involved in schizophrenia by inhibiting serotonin-1A (5-HT(1A)) receptor function. We examined the effects of estrogen pre-treatment on modulation of loudness dependence of the Auditory Evoked Potential (LDAEP) and mismatch negativity by the 5-HT(1A) receptor partial agonist, buspirone. Using a double-blind, placebo-controlled, repeated-measures design in healthy female volunteers, we observed that buspirone treatment significantly increased LDAEP slope. Estrogen increased LDAEP slope on its own, and a further LDAEP increase by buspirone was not seen after estrogen pre-treatment. Similar results were observed for mismatch negativity, where buspirone caused a small increase of latency, although not amplitude, after placebo but not estrogen pre-treatment, which enhanced mismatch negativity latency on its own. These results are in line with our previous findings on prepulse inhibition showing an inhibitory effect of estrogen on the action of buspirone. Taken together, these data suggest that estrogen may inhibit 5-HT(1A) receptor-mediated disruptions of Auditory processing.
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evidence for sex differences in the loudness dependence of the Auditory Evoked Potential in humans
Human Psychopharmacology-clinical and Experimental, 2011Co-Authors: Jessica Lee Oliva, Rodney J Croft, Pradeep J Nathan, Barry V Oneill, Sumie Leung, Julie C StoutAbstract:Objective: The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a marker of the serotonin system, although studies directly examining the relationship between acute changes in serotonin and the LDAEP have been inconsistent. Given the reported sex dichotomy in serotonin neurotransmission, this study examined if there are sex differences in the LDAEP. Methods: Data from 65 healthy participants from four independent studies were pooled, and their N1/P2 slopes were quantified. Results: Mean N1/P2 slopes for female participants were higher than those for male participants (p < 0.0001). Conclusion: These findings suggest that the LDAEP is modulated by sex Potentially because of differences in serotonergic neurotransmission, and these differences may account for some of the inconsistent findings linking serotonin function and LDAEP.
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the loudness dependence Auditory Evoked Potential is insensitive to acute changes in serotonergic and noradrenergic neurotransmission
Human Psychopharmacology-clinical and Experimental, 2010Co-Authors: Jessica Lee Oliva, Rodney J Croft, Luan K Phan, Pradeep J Nathan, Barry V Oneill, Sumie Leung, Julie C Stout, Joanne OkaneAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been proposed as an electrophysiological marker for assessing serotonergic function in vivo in humans, although accumulating evidence suggests that it is insensitive to acute changes in serotonergic neurotransmission. Very little is known about the sensitivity of the LDAEP to other neurotransmitter systems including the noradrenergic system. The current study examined the effects of noradrenergic modulation as well as serotonergic modulation on the LDAEP. Methods The study utilised a double-blind placebo-controlled design in which the LDAEP in 17 healthy males and females was tested following acute administration of each of citalopram (20 mg), reboxetine (4 mg) and placebo. Results Neither citalopram nor reboxetine modulated the LDAEP relative to placebo treatment (p > 0.05). Conclusion These findings suggest that the LDAEP is insensitive to acute changes in serotonergic or noradrenergic neurotransmission and thus is a poor pharmacodynamic marker of these systems. Copyright # 2010 John Wiley & Sons, Ltd.
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effects of selective and combined serotonin and dopamine depletion on the loudness dependence of the Auditory Evoked Potential ldaep in humans
Human Psychopharmacology-clinical and Experimental, 2008Co-Authors: Rodney J Croft, Luan K Phan, Pradeep J Nathan, Valerie Guille, Barry V Oneill, Sumie Leung, Kirsty Elizabeth ScholesAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a possible in vivo measure of central serotonin function. However, more recent studies suggest that the LDAEP may be modulated by multiple neuromodulatory systems in addition to the serotonergic system. Accordingly we further examined the effects of selective serotonin, dopamine and simultaneous serotonin and dopamine depletion on the LDAEP in healthy subjects. Methods The study employed a placebo-controlled, double-blind, cross over design. Fourteen subjects were tested under four acute treatment conditions: placebo (balanced amino acid drink), tryptophan (serotonin) depletion (ATD), tyrosine/phenylalanine (dopamine) depletion (ATPD) and combined tryptophan/tyrosine/phenylalanine (serotonin and dopamine) depletion (CMD). Testing was conducted 5.5 h post-depletion and changes in the amplitude of the N1/P2 at varying intensities (60, 70, 80, 90, 100 dB) were examined at CZ. Results Greater than 80% plasma precursor depletion was achieved across all conditions. Despite significant depletion of monoamine precursors, ATD, (p = 0.318), ATPD (p = 0.061) and CMD (p = 0.104) had no effects on the LDAEP (60–100 dB). Conclusion Acute serotonin and dopamine depletion did not modulate the LDAEP. This finding adds support to growing evidence that the LDAEP is insensitive to acute changes in serotonin and dopamine neurotransmission. Copyright © 2008 John Wiley & Sons, Ltd.
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pindolol does not augment central serotonin function increases to citalopram in humans an Auditory Evoked Potential investigation
Pharmacology Biochemistry and Behavior, 2006Co-Authors: Rebecca Segrave, Rodney J Croft, Susan Illic, Luan K Phan, Pradeep J NathanAbstract:Animal studies have demonstrated that the co-administration of pindolol and selective serotonin reuptake inhibitors (SSRIs) potentiate serotonergic functioning to a greater degree than SSRIs alone. However, clinical trials of pindolol augmentation in patients with major depressive disorder have reported contradictory findings, and the central effects of this treatment regime on serotonin functioning in humans are unknown. The current double-blind placebo controlled repeated measures investigation used the loudness dependence Auditory Evoked Potential (LDAEP) to assess central serotonin functioning in healthy participants across three acute treatment conditions: placebo, citalopram (20 mg), and pindolol (10 mg)+citalopram (20 mg). The current paper focuses on the effects of pindolol augmentation of citalopram as compared to the administration of citalopram alone. Enhancement of serotonin function with citalopram in comparison to placebo decreased the slope of the LDAEP (i.e. weaker LDAEP). However, there were no significant differences between the changes in the LDAEP induced by co-administration of pindolol and citalopram compared to citalopram. The present results indicate that, in healthy controls, pindolol augmentation of SSRIs does not potentiate central serotonin function to a greater degree than the administration of an SSRI alone. The findings may provide further support for why pindolol may not be an effective therapeutic strategy to augment serotonin function and antidepressant response.
G N C Kenny - One of the best experts on this subject based on the ideXlab platform.
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relationship between bispectral index Auditory Evoked Potential index and effect site ec50 for propofol at two clinical end points
BJA: British Journal of Anaesthesia, 2003Co-Authors: S E Milne, Andrew Troy, Michael G Irwin, G N C KennyAbstract:Background Many anaesthetists are deterred from using total i.v. anaesthesia because of uncertainty over the concentration of propofol required to prevent awareness. We predicted blood and effect-site concentrations of propofol at two clinical end-points: loss of consciousness and no response to a painful stimulus. Methods Forty unpremedicated Caucasian patients were anaesthetized with i.v. propofol delivered by a Diprifusor target-controlled infusion (TCI). Bispectral index (BIS) and Auditory Evoked Potential index (AEPex) were measured and blood and effect-site propofol concentrations were predicted. Logistic regression was used to estimate population values for predicted blood and effect-site propofol concentrations at the clinical end-points and to correlate these with BIS and AEPex. Results The effect-site EC50 at loss of consciousness was 2.8 μm ml−1 with an EC05 and an EC95 of 1.5 and 4.1 μm ml−1, respectively. The predicted EC50 when there was no response to a tetanic stimulus was 5.2 μm ml−1 with an EC05 and an EC95 of 3.1 and 7.2 μm ml−1, respectively. Conclusions Unconsciousness and lack of response to a painful stimulus occur within a defined range of effect-site concentrations, predicted by Diprifusor TCI software.
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effects of the Auditory stimuli of an Auditory Evoked Potential system on levels of consciousness and on the bispectral index
BJA: British Journal of Anaesthesia, 2001Co-Authors: Anthony Absalom, N Sutcliffe, G N C KennyAbstract:Investigators in the field of depth of anaesthesia monitoring sometimes measure the Auditory Evoked Potential (AEP) and the Bispectral Index (BIS) concurrently. However, the Auditory stimuli required to generate an AEP may increase the level of consciousness, and cause an increase in the BIS. They may also alter the BIS by producing phase-locked harmonics in the surface electroencephalogram. The aim of this study was to determine if AEP stimuli have clinically significant effects on levels of consciousness and BIS values during sedation and general anaesthesia. Ten healthy adult patients were studied by measuring and recording the BIS for 6 epochs of 5 min each. The first 3 epochs took place during steady-state sedation, during which time the Observer's Assessment of Awareness/Sedation (OAA/S) score was also measured. The second 3 epochs took place during steady-state anaesthesia. During alternate epochs, patients were subjected to the Auditory stimuli generated by an AEP system. The Auditory stimuli were not associated with a change in BIS values (during sedation and anaesthesia) or OAA/S scores (sedation).
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Auditory Evoked Potential index predicts the depth of sedation and movement in response to skin incision during sevoflurane anesthesia
Anesthesiology, 2001Co-Authors: Tadayoshi Kurita, Takasumi Katoh, Shigehito Sato, Hideki Sano, Haralambos Mantzaridis, G N C KennyAbstract:Background The Auditory Evoked Potential (AEP) index, which is a single numerical parameter derived from the AEP in real time and which describes the underlying morphology of the AEP, has been studied as a monitor of anesthetic depth. The current study was designed to evaluate the accuracy of AEPindex for predicting depth of sedation and anesthesia during sevoflurane anesthesia. Methods In the first phase of the study, a single end-tidal sevoflurane concentration ranging from 0.5 to 0.9% was assigned randomly and administered to each of 50 patients. The AEPindex and the Bispectral Index (BIS) were obtained simultaneously. Sedation was assessed using the responsiveness portion of the observer’s assessment of alertness–sedation scale. In the second phase of the study, 10 additional patients were included, and the 60 patients who were scheduled to have skin incisions were observed for movement in response to skin incision at the end-tidal sevoflurane concentrations between 1.6 and 2.6%. The relation among AEPindex, BIS, sevoflurane concentration, sedation score, and movement or absence of movement after skin incision was determined. Prediction probability values for AEPindex, BIS, and sevoflurane concentration to predict depth of sedation and anesthesia were also calculated. Results The AEPindex, BIS, and sevoflurane concentration correlated closely with the sedation score. The prediction probability values for AEPindex, BIS, and sevoflurane concentration for sedation score were 0.820, 0.805, and 0.870, respectively, indicating a high predictive performance for depth of sedation. AEPindex and sevoflurane concentration successfully predicted movement after skin (prediction probability = 0.910 and 0.857, respectively), whereas BIS could not (prediction probability = 0.537). Conclusions Auditory Evoked Potential index can be a guide to the depth of sedation and movement in response to skin incision during Conclusions sevoflurane anesthesia.
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prediction of movement at laryngeal mask airway insertion comparison of Auditory Evoked Potential index bispectral index spectral edge frequency and median frequency
BJA: British Journal of Anaesthesia, 1999Co-Authors: Matsuyuki Doi, H. Mantzaridis, Roger Gajraj, G N C KennyAbstract:We have studied 46 patients to compare the efficacy of the Auditory Evoked Potential (AEP) index, bispectral index (BIS), 95% spectral edge frequency (SEF) and median frequency (MF) in predicting movement in response to insertion of the laryngeal mask airway (LMA). Anaesthesia was induced with target-controlled infusions of propofol and alfentanil. After loss of eyelash reflex and adequate jaw relaxation, the LMA was inserted without the assistance of a laryngoscope or neuromuscular blocker. Patients who showed any visible spontaneous muscle movement within 1 min of LMA insertion were defined as movers. Values in movers and non-movers at 30 s before LMA insertion were analysed. Only AEP index discriminated between movers and non-movers with a prediction probability of 0.872. BIS, SEF and MF could not predict movement at LMA insertion. AEP index was the most reliable predictor of movement in response to LMA insertion.
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relationship between calculated blood concentration of propofol and electrophysiological variables during emergence from anaesthesia comparison of bispectral index spectral edge frequency median frequency and Auditory Evoked Potential index
BJA: British Journal of Anaesthesia, 1997Co-Authors: Roger Gajraj, Haralambos Mantzaridis, G N C KennyAbstract:We studied four electrophysiological variables (bispectral index (BIS), 95% spectral edge frequency (SEF), median frequency (MF) and Auditory Evoked Potential index (AEP index) in 10 patients during emergence from anaesthesia. We compared correlation of the signals with gradually decreasing calculated blood propofol concentrations, and evaluated the signal differences between preinduction and emergence from anaesthesia. Values of BIS, MF and SEF correlated with calculated blood concentrations of propofol during emergence from anaesthesia. The correlation was best with BIS, but was poor with MF and SEF at low calculated blood propofol concentrations. Although AEP index values did not correlate with calculated blood concentrations of propofol during emergence from anaesthesia, values after eye opening and before anaesthesia were well distinguished from those during emergence from anaesthesia. BIS correlated best with calculated blood concentrations of propofol. AEP index appeared to distinguish the awake from asleep state.
Luan K Phan - One of the best experts on this subject based on the ideXlab platform.
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the loudness dependence Auditory Evoked Potential is insensitive to acute changes in serotonergic and noradrenergic neurotransmission
Human Psychopharmacology-clinical and Experimental, 2010Co-Authors: Jessica Lee Oliva, Rodney J Croft, Luan K Phan, Pradeep J Nathan, Barry V Oneill, Sumie Leung, Julie C Stout, Joanne OkaneAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been proposed as an electrophysiological marker for assessing serotonergic function in vivo in humans, although accumulating evidence suggests that it is insensitive to acute changes in serotonergic neurotransmission. Very little is known about the sensitivity of the LDAEP to other neurotransmitter systems including the noradrenergic system. The current study examined the effects of noradrenergic modulation as well as serotonergic modulation on the LDAEP. Methods The study utilised a double-blind placebo-controlled design in which the LDAEP in 17 healthy males and females was tested following acute administration of each of citalopram (20 mg), reboxetine (4 mg) and placebo. Results Neither citalopram nor reboxetine modulated the LDAEP relative to placebo treatment (p > 0.05). Conclusion These findings suggest that the LDAEP is insensitive to acute changes in serotonergic or noradrenergic neurotransmission and thus is a poor pharmacodynamic marker of these systems. Copyright # 2010 John Wiley & Sons, Ltd.
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effects of selective and combined serotonin and dopamine depletion on the loudness dependence of the Auditory Evoked Potential ldaep in humans
Human Psychopharmacology-clinical and Experimental, 2008Co-Authors: Rodney J Croft, Luan K Phan, Pradeep J Nathan, Valerie Guille, Barry V Oneill, Sumie Leung, Kirsty Elizabeth ScholesAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a possible in vivo measure of central serotonin function. However, more recent studies suggest that the LDAEP may be modulated by multiple neuromodulatory systems in addition to the serotonergic system. Accordingly we further examined the effects of selective serotonin, dopamine and simultaneous serotonin and dopamine depletion on the LDAEP in healthy subjects. Methods The study employed a placebo-controlled, double-blind, cross over design. Fourteen subjects were tested under four acute treatment conditions: placebo (balanced amino acid drink), tryptophan (serotonin) depletion (ATD), tyrosine/phenylalanine (dopamine) depletion (ATPD) and combined tryptophan/tyrosine/phenylalanine (serotonin and dopamine) depletion (CMD). Testing was conducted 5.5 h post-depletion and changes in the amplitude of the N1/P2 at varying intensities (60, 70, 80, 90, 100 dB) were examined at CZ. Results Greater than 80% plasma precursor depletion was achieved across all conditions. Despite significant depletion of monoamine precursors, ATD, (p = 0.318), ATPD (p = 0.061) and CMD (p = 0.104) had no effects on the LDAEP (60–100 dB). Conclusion Acute serotonin and dopamine depletion did not modulate the LDAEP. This finding adds support to growing evidence that the LDAEP is insensitive to acute changes in serotonin and dopamine neurotransmission. Copyright © 2008 John Wiley & Sons, Ltd.
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pindolol does not augment central serotonin function increases to citalopram in humans an Auditory Evoked Potential investigation
Pharmacology Biochemistry and Behavior, 2006Co-Authors: Rebecca Segrave, Rodney J Croft, Susan Illic, Luan K Phan, Pradeep J NathanAbstract:Animal studies have demonstrated that the co-administration of pindolol and selective serotonin reuptake inhibitors (SSRIs) potentiate serotonergic functioning to a greater degree than SSRIs alone. However, clinical trials of pindolol augmentation in patients with major depressive disorder have reported contradictory findings, and the central effects of this treatment regime on serotonin functioning in humans are unknown. The current double-blind placebo controlled repeated measures investigation used the loudness dependence Auditory Evoked Potential (LDAEP) to assess central serotonin functioning in healthy participants across three acute treatment conditions: placebo, citalopram (20 mg), and pindolol (10 mg)+citalopram (20 mg). The current paper focuses on the effects of pindolol augmentation of citalopram as compared to the administration of citalopram alone. Enhancement of serotonin function with citalopram in comparison to placebo decreased the slope of the LDAEP (i.e. weaker LDAEP). However, there were no significant differences between the changes in the LDAEP induced by co-administration of pindolol and citalopram compared to citalopram. The present results indicate that, in healthy controls, pindolol augmentation of SSRIs does not potentiate central serotonin function to a greater degree than the administration of an SSRI alone. The findings may provide further support for why pindolol may not be an effective therapeutic strategy to augment serotonin function and antidepressant response.
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dopamine receptor stimulation does not modulate the loudness dependence of the Auditory Evoked Potential in humans
Psychopharmacology, 2006Co-Authors: Barry V Oneill, Rodney J Croft, Luan K Phan, Valerie Guille, Sumie Leung, Matthew P Galloway, Pradeep J NathanAbstract:Rationale The Loudness Dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a reliable measure of central serotonin function in humans; however, its specificity for the serotonin system remains a topic of debate, with possible modulation of this purported serotonin marker by other neurotransmitters, including dopamine.
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direct evidence that acutely enhancing serotonin with the selective serotonin reuptake inhibitor citalopram modulates the loudness dependence of the Auditory Evoked Potential ldaep marker of central serotonin function
Human Psychopharmacology-clinical and Experimental, 2006Co-Authors: Pradeep J Nathan, Rebecca Segrave, Rodney J Croft, Luan K Phan, Barry V OneillAbstract:The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a reliable measure of central serotonin function in humans. The most convincing evidence for a direct relationship between serotonergic function and LDAEP to date has come from animal studies, while evidence in humans has been circumstantial and inconsistent. In the current study, we examine the direct effect of serotonergic modulation with the selective serotonin reuptake inhibitor (SSRI) citalopram on the LDAEP. The study was a double-blind placebo controlled design in which healthy participants were tested under two acute treatment conditions: placebo and citalopram (20 mg). Enhancement of serotonin function with citalopram in comparison to placebo decreased the slope of the LDAEP (i.e. weaker LDAEP). The findings provide direct evidence in humans, of a relationship between central serotonin function and the LDAEP, supporting findings previously observed in animals and clinical populations. Together the results provide further support for the validity of the LDAEP as a non-invasive in vivo measure of central serotonin function in humans.
Barry V Oneill - One of the best experts on this subject based on the ideXlab platform.
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evidence for sex differences in the loudness dependence of the Auditory Evoked Potential in humans
Human Psychopharmacology-clinical and Experimental, 2011Co-Authors: Jessica Lee Oliva, Rodney J Croft, Pradeep J Nathan, Barry V Oneill, Sumie Leung, Julie C StoutAbstract:Objective: The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a marker of the serotonin system, although studies directly examining the relationship between acute changes in serotonin and the LDAEP have been inconsistent. Given the reported sex dichotomy in serotonin neurotransmission, this study examined if there are sex differences in the LDAEP. Methods: Data from 65 healthy participants from four independent studies were pooled, and their N1/P2 slopes were quantified. Results: Mean N1/P2 slopes for female participants were higher than those for male participants (p < 0.0001). Conclusion: These findings suggest that the LDAEP is modulated by sex Potentially because of differences in serotonergic neurotransmission, and these differences may account for some of the inconsistent findings linking serotonin function and LDAEP.
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the loudness dependence Auditory Evoked Potential is insensitive to acute changes in serotonergic and noradrenergic neurotransmission
Human Psychopharmacology-clinical and Experimental, 2010Co-Authors: Jessica Lee Oliva, Rodney J Croft, Luan K Phan, Pradeep J Nathan, Barry V Oneill, Sumie Leung, Julie C Stout, Joanne OkaneAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been proposed as an electrophysiological marker for assessing serotonergic function in vivo in humans, although accumulating evidence suggests that it is insensitive to acute changes in serotonergic neurotransmission. Very little is known about the sensitivity of the LDAEP to other neurotransmitter systems including the noradrenergic system. The current study examined the effects of noradrenergic modulation as well as serotonergic modulation on the LDAEP. Methods The study utilised a double-blind placebo-controlled design in which the LDAEP in 17 healthy males and females was tested following acute administration of each of citalopram (20 mg), reboxetine (4 mg) and placebo. Results Neither citalopram nor reboxetine modulated the LDAEP relative to placebo treatment (p > 0.05). Conclusion These findings suggest that the LDAEP is insensitive to acute changes in serotonergic or noradrenergic neurotransmission and thus is a poor pharmacodynamic marker of these systems. Copyright # 2010 John Wiley & Sons, Ltd.
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effects of selective and combined serotonin and dopamine depletion on the loudness dependence of the Auditory Evoked Potential ldaep in humans
Human Psychopharmacology-clinical and Experimental, 2008Co-Authors: Rodney J Croft, Luan K Phan, Pradeep J Nathan, Valerie Guille, Barry V Oneill, Sumie Leung, Kirsty Elizabeth ScholesAbstract:Background The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a possible in vivo measure of central serotonin function. However, more recent studies suggest that the LDAEP may be modulated by multiple neuromodulatory systems in addition to the serotonergic system. Accordingly we further examined the effects of selective serotonin, dopamine and simultaneous serotonin and dopamine depletion on the LDAEP in healthy subjects. Methods The study employed a placebo-controlled, double-blind, cross over design. Fourteen subjects were tested under four acute treatment conditions: placebo (balanced amino acid drink), tryptophan (serotonin) depletion (ATD), tyrosine/phenylalanine (dopamine) depletion (ATPD) and combined tryptophan/tyrosine/phenylalanine (serotonin and dopamine) depletion (CMD). Testing was conducted 5.5 h post-depletion and changes in the amplitude of the N1/P2 at varying intensities (60, 70, 80, 90, 100 dB) were examined at CZ. Results Greater than 80% plasma precursor depletion was achieved across all conditions. Despite significant depletion of monoamine precursors, ATD, (p = 0.318), ATPD (p = 0.061) and CMD (p = 0.104) had no effects on the LDAEP (60–100 dB). Conclusion Acute serotonin and dopamine depletion did not modulate the LDAEP. This finding adds support to growing evidence that the LDAEP is insensitive to acute changes in serotonin and dopamine neurotransmission. Copyright © 2008 John Wiley & Sons, Ltd.
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dopamine receptor stimulation does not modulate the loudness dependence of the Auditory Evoked Potential in humans
Psychopharmacology, 2006Co-Authors: Barry V Oneill, Rodney J Croft, Luan K Phan, Valerie Guille, Sumie Leung, Matthew P Galloway, Pradeep J NathanAbstract:Rationale The Loudness Dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a reliable measure of central serotonin function in humans; however, its specificity for the serotonin system remains a topic of debate, with possible modulation of this purported serotonin marker by other neurotransmitters, including dopamine.
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direct evidence that acutely enhancing serotonin with the selective serotonin reuptake inhibitor citalopram modulates the loudness dependence of the Auditory Evoked Potential ldaep marker of central serotonin function
Human Psychopharmacology-clinical and Experimental, 2006Co-Authors: Pradeep J Nathan, Rebecca Segrave, Rodney J Croft, Luan K Phan, Barry V OneillAbstract:The loudness dependence of the Auditory Evoked Potential (LDAEP) has been suggested as a reliable measure of central serotonin function in humans. The most convincing evidence for a direct relationship between serotonergic function and LDAEP to date has come from animal studies, while evidence in humans has been circumstantial and inconsistent. In the current study, we examine the direct effect of serotonergic modulation with the selective serotonin reuptake inhibitor (SSRI) citalopram on the LDAEP. The study was a double-blind placebo controlled design in which healthy participants were tested under two acute treatment conditions: placebo and citalopram (20 mg). Enhancement of serotonin function with citalopram in comparison to placebo decreased the slope of the LDAEP (i.e. weaker LDAEP). The findings provide direct evidence in humans, of a relationship between central serotonin function and the LDAEP, supporting findings previously observed in animals and clinical populations. Together the results provide further support for the validity of the LDAEP as a non-invasive in vivo measure of central serotonin function in humans.