The Experts below are selected from a list of 2256 Experts worldwide ranked by ideXlab platform
Leda Menescaldeoliveira - One of the best experts on this subject based on the ideXlab platform.
-
rostral ventromedial medulla connections in cavia porcellus and their relation with Tonic Immobility defensive behavior a biotinylated dextran amine neurotracing study
Neuroscience Letters, 2013Co-Authors: Luís F. Silva, Norberto Cysne Coimbra, Leda MenescaldeoliveiraAbstract:Abstract The rostroventromedial medulla (RVM), together with the periaqueductal gray matter (PAG), constitutes the descendent antinociceptive system. Additionally, these structures mutually regulate defensive behaviors, including Tonic Immobility (TI) in guinea pigs. The current study was undertaken to evaluate the connections of the RVM with the PAG and the spinal cord in guinea pigs in order to provide an anatomical basis for the role played by RVM in the modulation of TI. To address this goal, five guinea pigs were treated with non-fluorescent biotinylated dextran amine (BDA) neurotracer by injection into the RVM. After four days of survival, the encephalon and spinal cord were removed from each rodent, and BDA labeling was visualized with a standard avidin-biotinylated horseradish peroxidase method through reaction with nickel-intensified peroxidase 3,3′-diaminobenzidine dihydrochloride. The microinjection of BDA into the RVM stained fibers in the ventral horn, dorsal horn and intermediate gray matter of the spinal cord. BDA-labeled fibers, terminal buttons suggesting synaptic contacts, and perikarya were found in the dorsomedial, dorsolateral, lateral and ventrolateral PAG, and neuronal somata were identified in the cuneiform nucleus. Together, the current data demonstrate neuroanatomical evidence that supports the role of the RVM in the modulation of TI defensive behavior.
-
rostral ventromedial medulla modulates nociception and Tonic Immobility behavior through connections with the a7 catecholaminergic region
Behavioural Brain Research, 2012Co-Authors: Luís F. Silva, Norberto Cysne Coimbra, Leda MenescaldeoliveiraAbstract:Abstract Cholinergic stimulation of the rostral ventromedial medulla (RVM) produces antinociception and reduces the duration of Tonic Immobility (TI) behavior in guinea pigs. Previous studies indicated that cholinergic antinociception in the RVM is mediated through connections with the A7 catecholaminergic cell group (A7). In the current study, we tested the role of the A7 in both the antinociception and reduction of TI duration mediated by cholinergic stimulation of the RVM. In addition, we used biotinylated dextran amines (BDA) to evaluate the connections between the RVM and A7. The microinjection of the cholinergic agonist carbachol into the RVM produced antinociception and reduced TI behavior duration. These effects were blocked by prior administration of lidocaine to the A7. However, the microinjection of lidocaine into the A7 prior to saline injection into the RVM had no effect on either the nociceptive or TI responses. The microinjection of the neurotracer BDA into the RVM positively stained fibers and synaptic boutons in the A7, indicating that there are direct projections from the RVM to the A7. Taken together, our results indicate that the antinociception and reduction of TI behavior duration after cholinergic stimulation of the RVM depends on connections with the A7.
-
role of homocysteic acid in the guinea pig cavia porcellus anterior cingulate cortex in Tonic Immobility and the influence of nmda receptors on the dorsal pag
Behavioural Brain Research, 2010Co-Authors: Marcio Ramos Coutinho, Leda MenescaldeoliveiraAbstract:Abstract Tonic Immobility (TI) is an innate defensive behaviour elicited by physical restriction and postural inversion, and is characterised by a profound and temporary state of akinesis. Our previous studies demonstrated that glutamatergic stimulation of the dorsomedial/dorsolateral portion of periaqueductal gray matter (dPAG) decreases the duration of TI in guinea pigs ( Cavia porcellus ). Furthermore, evidence suggests that the anterior cingulate cortex (ACC) constitutes an important source of glutamate for the dPAG. Hence, in the current study, we investigated the effects of microinjection of the excitatory amino acid (EAA) agonist dl -homocysteic acid (DLH) and the N-methyl- d -aspartate (NMDA) receptor antagonist MK-801 into the ACC on the duration of TI in guinea pigs. We also assessed the effect of the NMDA receptor antagonist (MK-801) into the dorsal periaqueductal gray matter (dPAG) prior to DLH microinjection into the ACC on the TI duration in the guinea pig. Our results demonstrated that DLH microinjections into the ACC decreased the duration of TI. This effect was blocked by previous MK-801 microinjections into the ACC or into the dPAG. The MK-801 microinjections alone did not influence TI duration. These results provide the new insight that EAAs in the ACC can decrease the duration of TI. The mechanism seems to be dependent on the NMDA receptors present in the ACC and in the dPAG.
-
role of opioidergic and gabaergic neurotransmission of the nucleus raphe magnus in the modulation of Tonic Immobility in guinea pigs
Brain Research Bulletin, 2007Co-Authors: Luís F. Silva, Leda MenescaldeoliveiraAbstract:Abstract Tonic Immobility (TI) is an inborn defensive behavior characterized by a temporary state of profound and reversible motor inhibition elicited by some forms of physical restraint. Previous results from our laboratory have demonstrated that nucleus raphe magnus (NRM) is also a structure involved in the modulation of TI behavior, as chemical stimulation through carbachol decreases the duration of TI in guinea pigs. In view of the fact that GABAergic and opioidergic circuits participate in the regulation of neuronal activity in the NRM and since these neurotransmitters are also involved in the modulation of TI, the objective of the present study was to evaluate the role of these circuits of the NRM in the modulation of the behavioral TI response. Microinjection of morphine (4.4 nmol/0.2 μl) or bicuculline (0.4 nmol/0.2 μl) into the NRM increased the duration of TI episodes while muscimol (0.5 nmol/0.2 μl) decreased it. The effect of morphine injection into the NRM was blocked by previous microinjection of naloxone (2.7 nmol/0.2 μl). Muscimol at 0.25 nmol did not produce any change in TI duration; however, it blocked the increased response induced by morphine. Our results indicate a facilitatory role of opioidergic neurotransmission in the modulation of the TI response within the NRM, whereas GABAergic activity plays an inhibitory role. In addition, in the present study the modulation of TI in the NRM possibly occurred via an interaction between opioidergic and GABAergic systems, where the opioidergic effect might be due to inhibition of Tonically active GABAergic interneurons.
-
serotonin 5 ht2 and 5 ht1a receptors in the periaqueductal gray matter differentially modulate Tonic Immobility in guinea pig
Brain Research, 2004Co-Authors: C R Monassi, Leda MenescaldeoliveiraAbstract:Abstract Tonic Immobility (TI) is an inborn defensive behavior characterized by a temporary state of profound and reversible motor inhibition elicited by some forms of physical restraint. We have previously reported that cholinergic stimulation of the dorsal periaqueductal gray matter (PAG) decreases the duration of TI episodes, while stimulation of the ventrolateral region increases it. The ventrolateral PAG modulates this behavior via a similar neural circuit proposed to be involved in the antinociceptive system. Some studies have indicated that alterations in the levels of cerebral 5-hydroxytryptamine (5-HT) mediate or modulate the analgesic effect of PAG stimulation. Thus, in this study we investigated the possibility that the serotoninergic system is involved in the modulation of TI by this neural substrate. Our results showed that the effect of serotonin into the ventrolateral and dorsal PAG seems to be biphasic and dose dependent. The microinjection of low doses (0.1 μg) of 5-HT into the PAG increased the duration of TI, while high doses (1, 3 and 6 μg) decreased this behavior. Our results also showed that microinjection of a 5-HT1A agonist (0.003, 0.01 and 0.1 μg of 8-hydroxy-dipropylaminotretalin (8-OH-DPAT)) into the PAG increased the duration of TI episodes. However, the microinjection of 5-HT2 agonist (0.01 and 0.1 μg of α-methyl-5-HT) into the PAG decreased the duration of TI and this effect could be reversed by pretreatment with an ineffective dose (0.01 μg) of ketanserin. In contrast, ketanserin (0.03 and 0.16 μg) increased this behavior in a dose-dependent manner. These results suggest that the PAG 5-HT1A and 5-HT2 receptors have different roles in the modulation of TI in guinea pigs, since the 5-HT1A and 5-HT2 agonists, respectively, increased and decreased the duration of TI.
J L Campo - One of the best experts on this subject based on the ideXlab platform.
-
GENETICS Influence of Perches and Footpad Dermatitis on Tonic Immobility and Heterophil to Lymphocyte Ratio of Chickens
2016Co-Authors: J L Campo, M. G. Gil, S. G. DávilaAbstract:ABSTRACT The purpose of the present study was to analyze the effect of perches and footpad dermatitis on stress and fear levels of chickens. In experiment 1 hetero-phil to lymphocyte ratio and Tonic Immobility duration were measured in 36-wk-old hens (36 birds) from 2 Span-ish breeds of chickens (Black Menorca and Quail Castellana) housed in pens with or without perches from 20 wk of age. There was a significant difference in the heterophil to lymphocyte ratio between perch treatments (P < 0.05), the ratio of hens with perches being lower than that of hens without perches. Hens with perches had significant lymphophilia (P < 0.05). There was no signifi-cant difference for the duration of Tonic Immobility be-tween hens with or without perches. Thus, hens with perches were less stressed than hens without perches, as indicated by the heterophil to lymphocyte ratio. Hetero-phil to lymphocyte ratio and heterophil number for Black Menorcas were significantly smaller (P < 0.001) than for Quail Castellanas, whereas lymphocyte number wa
-
comparison of the Tonic Immobility duration heterophil to lymphocyte ratio and fluctuating asymmetry of chicks reared with or without a broody hen and of broody and non broody hens
Applied Animal Behaviour Science, 2014Co-Authors: J L Campo, Sara Garcia Davila, Maria Garcia GilAbstract:Abstract The purposes of this study were to determine whether rearing with a broody hen influenced duration of Tonic Immobility, heterophil to lymphocyte ratio, and relative fluctuating asymmetry of chicks and to analyze the differences between broody and non-broody hens in fear and stress indicators. A total of 120 chicks (60 reared with a broody hen and 60 reared without a broody hen), and 48 hens (24 broody and 24 non-broody) were analyzed at 6 and 52 weeks of age, respectively. Broody hens were observed in 12 different Spanish breeds (Blue Andaluza, Black-barred Andaluza, Black Red Andaluza, Black Castellana, White-faced Spanish, Buff Prat, White Prat, Birchen Leonesa, Quail Castellana, Quail Silver Castellana, Red-barred Vasca, and Red Villafranquina), and all the chicks were from an F 1 cross between the Black-barred Andaluza and the Black Castellana breeds. Tonic Immobility duration was significantly longer ( P
-
associations among fluctuating asymmetry Tonic Immobility duration and flight distance or ease of capture in chickens
Poultry Science, 2012Co-Authors: J L Campo, S G Davila, M T PrietoAbstract:ABSTRACT The purpose of this study was to analyze the associations among fluctuating asymmetry, duration of Tonic Immobility, and flight performance or ease of capture in chickens. Cocks (n = 220; 36 wk old) from 10 Spanish breeds and a White Leghorn population were used. The quantitative/qualitative relationship among fluctuating asymmetry, duration of Tonic Immobility, and landing accuracy (good or bad) or landing distance (long or short), and the quantitative/quantitative relationship among fluctuating asymmetry, duration of Tonic Immobility, and time of capture or number of attempts of capture were studied. Relative fluctuating asymmetry of toe length, wing length, and the combined relative asymmetry of toe length, leg length, wing length, and leg width was significantly greater (P
-
effects of auditory and physical enrichment on 3 measurements of fear and stress Tonic Immobility duration heterophil to lymphocyte ratio and fluctuating asymmetry in several breeds of layer chicks
Poultry Science, 2011Co-Authors: S G Davila, J L Campo, M T Prieto, M. G. Gil, O TorresAbstract:The purpose of this study was to analyze the effect of auditory enrichment (by means of classical music) or physical enrichment (by means of hanging colored string bunches and barley grains on the floor) on Tonic Immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry (FA) in chicks of several layer breeds. In experiment 1, 192 chicks from 8 Spanish breeds and 1 White Leghorn population were reared in cages with or without music auditory enrichment until 8 wk of age. The effect of music auditory enrichment was significant for heterophil to lymphocyte ratio (P < 0.05). The ratios were higher in chicks reared without music than in those reared with music, suggesting that auditory enrichment from classical music reduces stress in chicks. There were significant differences in morphological trait measurements (relative asymmetry of wing length, leg width, and combined asymmetry; P < 0.05), being greater in chicks reared without music. This result suggests that FA is a good indicator for stress level in chicks, given that it follows the same trend as that found for heterophil to lymphocyte ratio. There was a significant treatment by breed interaction (P < 0.05) for Tonic Immobility duration, indicating no consistent effect by auditory enrichment on Tonic Immobility duration across breeds. In experiment 2, 180 chicks from 3 Spanish breeds were housed in pens with or without physical enrichment (colored plastic string bunches and barley grains on the floor) until 6 wk of age. The effect of physical enrichment on Tonic Immobility duration, heterophil to lymphocyte ratio, and FA was not significant, indicating no effect on fear and stress in layer chicks. In conclusion, auditory enrichment by means of classical music is a reliable method for reducing stress levels in several breeds of layer chicks. However, music auditory enrichment was not effective in reducing fearfulness in any of the layer breeds. Physical enrichment by means of colored plastic string bunches and floor barley grains does not appear to be an effective method for reducing stress and fear in layer chicks.
-
effect of heat and several additives related to stress levels on fluctuating asymmetry heterophil lymphocyte ratio and Tonic Immobility duration in white leghorn chicks
Poultry Science, 2010Co-Authors: M T Prieto, J L CampoAbstract:The purpose of this study was to analyze the effects of heat and several additives related to stress on fluctuating asymmetry (groups 1 to 10), heterophil:lymphocyte ratio (groups 1 to 3 and 8 to 10), and Tonic Immobility duration (groups 1 to 7 and 10) in White Leghorn chicks at 42 d of age. Chicks in group 1 (heat) were reared with temperatures 8°C greater than those of the control group. Groups 2 to 9 consisted of chicks reared with temperatures 8°C greater than those of the control group and addition of capsaicin, allicin, ascorbic acid, tryptophan, brewer's yeast, lactic acid, corticosterone, or cholesterol in diet. Chicks in group 10 (control) were reared with standard temperatures. Heat effect was significant (P<0.05) for the heterophil:lymphocyte ratio, which was greater in heat-stressed chicks without any additives and smaller in control chicks. There were no significant differences for the fluctuating asymmetry and the Tonic Immobility duration between both groups. Heterophil:lymphocyte ratio for heat-stressed chicks with capsaicin or allicin was significantly lower (P<0.05) than that of heat-stressed chicks without any additives. Capsaicin effect was not significant for the fluctuating asymmetry and the Tonic Immobility duration, whereas allicin significantly increased fluctuating asymmetry of wing length and Tonic Immobility duration (P<0.05). The addition of lactic acid or corticosterone resulted in greater fluctuating asymmetry of wing length of heat-stressed chicks (P<0.05). In conclusion, an increased heterophil:lymphocyte ratio was found in heat-stressed chicks without additives, indicating that it is a more reliable indicator of the effect of heat in chicks. In addition, dietary capsaicin or allicin supplementation was effective to alleviate the stress induced by the high temperature, as indicated by a lower heterophil:lymphocyte ratio.
Norberto Cysne Coimbra - One of the best experts on this subject based on the ideXlab platform.
-
restricted lesions of the ventrolateral or dorsal columns of the periaqueductal gray promotes distinct effects on Tonic Immobility and defensive analgesia in guinea pigs
Physiology & Behavior, 2018Co-Authors: Eveline Bis Vieirarasteli, Norberto Cysne Coimbra, Bruna Balbino De Paula, Yara Bezerra De Paiva, Christie Ramos Andrade LeitepanissiAbstract:Abstract Tonic Immobility (TI) is an innate defensive response exhibited by prey when physical contact with a predator is prolonged and inescapable. This defensive response is able to activate analgesia mechanisms; this activation has adaptive value because, during an attack by a predator, the manifestation of recuperative behaviors can affect the appropriate behavioral defense strategy. Some studies have suggested that similar structures of the central nervous system can regulate the response of both TI and nociception. Thus, this study evaluated the effect of chemical lesion through the administration of ibotenic acid in restricted brain areas of the periaqueductal gray matter (PAG) in guinea pig on the TI response and nociception evaluated in the hot plate test before and after emission of TI. The data showed that an irreversible chemical lesion in the ventrolateral PAG reduced of the TI response as well as defensive antinociception. However, a lesion in the dorsal PAG blocked the defensive antinociception induced by TI but did not alter TI duration. In summary, one could hypothesize that the neural substrates responsible for defensive behavior and antinociception represent similar systems that are distinct in modulation. Thus, the ventrolateral PAG has been associated with the modulation of TI and the defensive antinociception induced by TI. In contrast, the integrity of the dorsal PAG should be necessary for defensive antinociception to occur but not to elicit TI behavior in guinea pigs.
-
rostral ventromedial medulla connections in cavia porcellus and their relation with Tonic Immobility defensive behavior a biotinylated dextran amine neurotracing study
Neuroscience Letters, 2013Co-Authors: Luís F. Silva, Norberto Cysne Coimbra, Leda MenescaldeoliveiraAbstract:Abstract The rostroventromedial medulla (RVM), together with the periaqueductal gray matter (PAG), constitutes the descendent antinociceptive system. Additionally, these structures mutually regulate defensive behaviors, including Tonic Immobility (TI) in guinea pigs. The current study was undertaken to evaluate the connections of the RVM with the PAG and the spinal cord in guinea pigs in order to provide an anatomical basis for the role played by RVM in the modulation of TI. To address this goal, five guinea pigs were treated with non-fluorescent biotinylated dextran amine (BDA) neurotracer by injection into the RVM. After four days of survival, the encephalon and spinal cord were removed from each rodent, and BDA labeling was visualized with a standard avidin-biotinylated horseradish peroxidase method through reaction with nickel-intensified peroxidase 3,3′-diaminobenzidine dihydrochloride. The microinjection of BDA into the RVM stained fibers in the ventral horn, dorsal horn and intermediate gray matter of the spinal cord. BDA-labeled fibers, terminal buttons suggesting synaptic contacts, and perikarya were found in the dorsomedial, dorsolateral, lateral and ventrolateral PAG, and neuronal somata were identified in the cuneiform nucleus. Together, the current data demonstrate neuroanatomical evidence that supports the role of the RVM in the modulation of TI defensive behavior.
-
rostral ventromedial medulla modulates nociception and Tonic Immobility behavior through connections with the a7 catecholaminergic region
Behavioural Brain Research, 2012Co-Authors: Luís F. Silva, Norberto Cysne Coimbra, Leda MenescaldeoliveiraAbstract:Abstract Cholinergic stimulation of the rostral ventromedial medulla (RVM) produces antinociception and reduces the duration of Tonic Immobility (TI) behavior in guinea pigs. Previous studies indicated that cholinergic antinociception in the RVM is mediated through connections with the A7 catecholaminergic cell group (A7). In the current study, we tested the role of the A7 in both the antinociception and reduction of TI duration mediated by cholinergic stimulation of the RVM. In addition, we used biotinylated dextran amines (BDA) to evaluate the connections between the RVM and A7. The microinjection of the cholinergic agonist carbachol into the RVM produced antinociception and reduced TI behavior duration. These effects were blocked by prior administration of lidocaine to the A7. However, the microinjection of lidocaine into the A7 prior to saline injection into the RVM had no effect on either the nociceptive or TI responses. The microinjection of the neurotracer BDA into the RVM positively stained fibers and synaptic boutons in the A7, indicating that there are direct projections from the RVM to the A7. Taken together, our results indicate that the antinociception and reduction of TI behavior duration after cholinergic stimulation of the RVM depends on connections with the A7.
-
the cholinergic stimulation of the central amygdala modifying the Tonic Immobility response and antinociception in guinea pigs depends on the ventrolateral periaqueductal gray
Brain Research Bulletin, 2003Co-Authors: Christie Ramos Andrade Leitepanissi, Norberto Cysne Coimbra, Leda MenescaldeoliveiraAbstract:Abstract Tonic Immobility (TI), also known as death feigning or animal hypnosis, is a reversible state of motor inhibition that is triggered by postural inversion and/or movement restraining maneuvers but also by repetitive stimulation and pressure on body parts. Our previous studies demonstrated that cholinergic stimulation of the central amygdala (CEA) decreases the duration of TI in guinea pigs. Some reports have demonstrated that electrical or chemical stimulation of the CEA promotes antinociception. Evidence suggests that the CEA performs part of its functions by means of a connection with the ventrolateral periaqueductal gray (vlPAG). In the current study, we investigated the participation of a possible functional and anatomical CEA–vlPAG connection in guinea pigs in the regulation of the TI response and antinociception. Our results showed that the functional CEA–vlPAG connection is essential for the participation of the CEA in the modulation of TI and of antinociception. The reversible exclusion of the vlPAG by means of microinjection of 2% lidocaine blocked the inhibitory effect on TI duration and the antinociceptive effect, as determined by a decrease of the vocalization index (VI) obtained with the administration of carbachol (2.7 nmol/0.2 μl) into the CEA. On the other hand, the exclusion of the CEA by lidocaine did not block the antinociception or the increase in TI induced by microinjection of CCh into the vlPAG. Finally, microinjection of the retrograde neurotracer Fast Blue into the CEA or into the vlPAG demonstrated the existence of a reciprocal anatomical connection between the CEA and vlPAG.
Robert John Young - One of the best experts on this subject based on the ideXlab platform.
-
Tonic Immobility test results for different wild and captive populations of golden mantella frogs.
2017Co-Authors: Luiza Figueiredo Passos, Gerardo Garcia, Robert John YoungAbstract:Tonic Immobility test results for different wild and captive populations of golden mantella frogs.
-
Scatter plot of body condition index (BCI) and Tonic Immobility (TI) response (s) of different populations of golden mantella frogs.
2017Co-Authors: Luiza Figueiredo Passos, Gerardo Garcia, Robert John YoungAbstract:Scatter plot of body condition index (BCI) and Tonic Immobility (TI) response (s) of different populations of golden mantella frogs.
-
Pearson correlation results for relationship between Tonic Immobility response (duration) and body condition index for different golden mantella frog populations.
2017Co-Authors: Luiza Figueiredo Passos, Gerardo Garcia, Robert John YoungAbstract:Pearson correlation results for relationship between Tonic Immobility response (duration) and body condition index for different golden mantella frog populations.
-
The Tonic Immobility test: Do wild and captive golden mantella frogs (Mantella aurantiaca) have the same response?
Public Library of Science (PLoS), 2024Co-Authors: Luiza Figueiredo Passos, Gerardo Garcia, Robert John YoungAbstract:Adaptations to captivity that reduce fitness are one of many reasons, which explain the low success rate of reintroductions. One way of testing this hypothesis is to compare an important behavioural response in captive and wild members of the same species. Thanatosis, is an anti-predator strategy that reduces the risk of death from predation, which is a common behavioral response in frogs. The study subjects for this investigation were captive and wild populations of Mantella aurantiaca. Thanatosis reaction was measured using the Tonic Immobility (TI) test, a method that consists of placing a frog on its back, restraining it in this position for a short period of time and then releasing it and measuring how much time was spent feigning death. To understand the pattern of reaction time, morphometric data were also collected as body condition can affect the duration of thanatosis. The significantly different TI times found in this study, one captive population with shorter responses, were principally an effect of body condition rather than being a result of rearing environment. However, this does not mean that we can always dismiss the importance of rearing environment in terms of behavioural skills expressed
Luís F. Silva - One of the best experts on this subject based on the ideXlab platform.
-
rostral ventromedial medulla connections in cavia porcellus and their relation with Tonic Immobility defensive behavior a biotinylated dextran amine neurotracing study
Neuroscience Letters, 2013Co-Authors: Luís F. Silva, Norberto Cysne Coimbra, Leda MenescaldeoliveiraAbstract:Abstract The rostroventromedial medulla (RVM), together with the periaqueductal gray matter (PAG), constitutes the descendent antinociceptive system. Additionally, these structures mutually regulate defensive behaviors, including Tonic Immobility (TI) in guinea pigs. The current study was undertaken to evaluate the connections of the RVM with the PAG and the spinal cord in guinea pigs in order to provide an anatomical basis for the role played by RVM in the modulation of TI. To address this goal, five guinea pigs were treated with non-fluorescent biotinylated dextran amine (BDA) neurotracer by injection into the RVM. After four days of survival, the encephalon and spinal cord were removed from each rodent, and BDA labeling was visualized with a standard avidin-biotinylated horseradish peroxidase method through reaction with nickel-intensified peroxidase 3,3′-diaminobenzidine dihydrochloride. The microinjection of BDA into the RVM stained fibers in the ventral horn, dorsal horn and intermediate gray matter of the spinal cord. BDA-labeled fibers, terminal buttons suggesting synaptic contacts, and perikarya were found in the dorsomedial, dorsolateral, lateral and ventrolateral PAG, and neuronal somata were identified in the cuneiform nucleus. Together, the current data demonstrate neuroanatomical evidence that supports the role of the RVM in the modulation of TI defensive behavior.
-
rostral ventromedial medulla modulates nociception and Tonic Immobility behavior through connections with the a7 catecholaminergic region
Behavioural Brain Research, 2012Co-Authors: Luís F. Silva, Norberto Cysne Coimbra, Leda MenescaldeoliveiraAbstract:Abstract Cholinergic stimulation of the rostral ventromedial medulla (RVM) produces antinociception and reduces the duration of Tonic Immobility (TI) behavior in guinea pigs. Previous studies indicated that cholinergic antinociception in the RVM is mediated through connections with the A7 catecholaminergic cell group (A7). In the current study, we tested the role of the A7 in both the antinociception and reduction of TI duration mediated by cholinergic stimulation of the RVM. In addition, we used biotinylated dextran amines (BDA) to evaluate the connections between the RVM and A7. The microinjection of the cholinergic agonist carbachol into the RVM produced antinociception and reduced TI behavior duration. These effects were blocked by prior administration of lidocaine to the A7. However, the microinjection of lidocaine into the A7 prior to saline injection into the RVM had no effect on either the nociceptive or TI responses. The microinjection of the neurotracer BDA into the RVM positively stained fibers and synaptic boutons in the A7, indicating that there are direct projections from the RVM to the A7. Taken together, our results indicate that the antinociception and reduction of TI behavior duration after cholinergic stimulation of the RVM depends on connections with the A7.
-
role of opioidergic and gabaergic neurotransmission of the nucleus raphe magnus in the modulation of Tonic Immobility in guinea pigs
Brain Research Bulletin, 2007Co-Authors: Luís F. Silva, Leda MenescaldeoliveiraAbstract:Abstract Tonic Immobility (TI) is an inborn defensive behavior characterized by a temporary state of profound and reversible motor inhibition elicited by some forms of physical restraint. Previous results from our laboratory have demonstrated that nucleus raphe magnus (NRM) is also a structure involved in the modulation of TI behavior, as chemical stimulation through carbachol decreases the duration of TI in guinea pigs. In view of the fact that GABAergic and opioidergic circuits participate in the regulation of neuronal activity in the NRM and since these neurotransmitters are also involved in the modulation of TI, the objective of the present study was to evaluate the role of these circuits of the NRM in the modulation of the behavioral TI response. Microinjection of morphine (4.4 nmol/0.2 μl) or bicuculline (0.4 nmol/0.2 μl) into the NRM increased the duration of TI episodes while muscimol (0.5 nmol/0.2 μl) decreased it. The effect of morphine injection into the NRM was blocked by previous microinjection of naloxone (2.7 nmol/0.2 μl). Muscimol at 0.25 nmol did not produce any change in TI duration; however, it blocked the increased response induced by morphine. Our results indicate a facilitatory role of opioidergic neurotransmission in the modulation of the TI response within the NRM, whereas GABAergic activity plays an inhibitory role. In addition, in the present study the modulation of TI in the NRM possibly occurred via an interaction between opioidergic and GABAergic systems, where the opioidergic effect might be due to inhibition of Tonically active GABAergic interneurons.
