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Randy J Nelson - One of the best experts on this subject based on the ideXlab platform.

  • food restriction affects the gonadotropin releasing hormone Neuronal System of male prairie voles microtus ochrogaster
    Journal of Neuroendocrinology, 2001
    Co-Authors: Lance J Kriegsfeld, N J Ranalli, A G Trasy, Randy J Nelson
    Abstract:

    Individuals of species inhabiting temperate and boreal latitudes optimize the timing of energetically costly processes by curtailing nonessential energetically demanding processes when environmental conditions are not favourable. One proximate environmental variable used to fine-tune moment-to-moment changes in reproductive physiology and behaviour is food intake. The neuroendocrine mechanisms by which food restriction leads to the cessation of reproduction in seasonally breeding rodent species remain largely unspecified. The present study sought to determine the effects of extended food restriction on the gonadotropin releasing hormone (GnRH) Neuronal System. Male prairie voles (Microtus ochrogaster) were either fed ad libitum or were exposed to either 1, 2 or 3 weeks of moderate (70% of daily mean) food restriction. In accordance with previous studies of food restriction, gross reproductive organ masses and body mass were unaffected by food deprivation. Although 1 week of food restriction did not result in alterations in the GnRH Neuronal System, food restriction for 2 weeks was associated with increased GnRH-immunoreactive (GnRH-ir) neurone soma size. Three weeks of food restriction resulted in a pronounced increase in GnRH-ir neurone numbers, as well as an increase in fibre intensity in the main fibre pathway to the median eminence. Taken together, these findings suggest that extended food restriction leads to modifications in the GnRH Neuronal System, providing a means for temporary cessation of reproduction without gross alterations in reproductive physiology. This transient change in the hypothalmo-pituitary-gonadal axis, without pronounced changes in reproductive organ morphology, likely provides a mechanism for the rapid reinitiation of breeding in nature when local conditions provide adequate food availability.

  • photoperiod and temperature interact to affect the gnrh Neuronal System of male prairie voles microtus ochrogaster
    Journal of Biological Rhythms, 2000
    Co-Authors: Lance J Kriegsfeld, N J Ranalli, Marie A Bober, Randy J Nelson
    Abstract:

    Individuals of numerous species limit energy expenditure during winter by inhibiting reproduction and other nonessential functions. To time these adaptations appropriately with the annual cycle, animals rely on environ- mental cues that predict, well in advance, the onset of winter. The most com- monly studied environmental factor that animals use to time reproduction is photoperiod. Rodents housed in short photoperiods in the laboratory or in natu- rally declining day lengths exhibit pronounced alterations in reproductive func- tion concomitant with alterations in the hypothalamic gonadotropin-releasing hormone Neuronal System. Because animals in their natural environment use fac- tors in addition to photoperiod to time reproduction, the present study sought to determine the independent effects of photoperiod and temperature, as well as the interaction between these factors, on reproductive parameters and the GnRH Neuronal System. Male prairie voles were housed in either long (LD 16:8) or short (LD 8:16) day lengths for 10 weeks. Animals in each photoperiod were further subdivided into groups housed in either mild (i.e., 20°C) or low (i.e., 8°C) temper- atures. As shown with immunohistochemistry, voles that underwent gonadal regression in response to short photoperiods and long-day voles housed in low temperatures (and maintained large gonads) exhibit higher GnRH- immunoreactive (GnRH-ir) neuron numbers in the preoptic area/anterior hypo- thalamus (POA/AH) relative to all other groups. In addition, voles that under- went gonadal regression in response to both short days and low temperatures did not exhibit an increase in GnRH-ir neuron numbers compared to long-day, mild-temperature controls. These data suggest that photoperiod and tempera- ture interact to influence reproductive function potentially by alterations of the GnRH Neuronal System.

  • photoperiod affects the gonadotropin releasing hormone Neuronal System of male prairie voles microtus ochrogaster
    Neuroendocrinology, 1999
    Co-Authors: Lance J Kriegsfeld, Randy J Nelson
    Abstract:

    In order to maximize survival, animals inhabiting temperate and boreal latitudes exhibit numerous adaptations to changing seasons. Central among this suite of coping strategies is the cessation of breeding during the suboptimal conditions of winter. Many nontropical rodents inhibit reproduction well in advance of winter in response to short day lengths. Male prairie voles (Microtus ochrogaster) are small temperate-zone rodents that vary in their reproductive response to photoperiod. Some male voles undergo complete gonadal regression during short days (responders) while others fail to inhibit reproduction when exposed to short day lengths (nonresponders). The neuroendocrine mechanisms regulating this differential response to photoperiod have not been investigated in this species. Presumably, photoperiod can act at any or all levels of the hypothalamo-pituitary-gonadal (HPG) axis to regulate reproduction. The present study sought to determine the contribution of the GnRH System to this variable reproductive response to photoperiod. Male prairie voles were housed in either long or short day lengths for 10 weeks. As shown with immunohistochemistry, voles that underwent gonadal regression in response to short photoperiods exhibited increased GnRH neuron numbers in the preoptic area/anterior hypothalamus (POA/AH) relative to both long-day animals and short-day voles that maintained reproductive function. Mean optical density of staining and cell size did not differ among groups. These data suggest that the differential reproductive response to photoperiod in male voles is mediated, in part, by alterations in the GnRH Neuronal System.

Lance J Kriegsfeld - One of the best experts on this subject based on the ideXlab platform.

  • food restriction affects the gonadotropin releasing hormone Neuronal System of male prairie voles microtus ochrogaster
    Journal of Neuroendocrinology, 2001
    Co-Authors: Lance J Kriegsfeld, N J Ranalli, A G Trasy, Randy J Nelson
    Abstract:

    Individuals of species inhabiting temperate and boreal latitudes optimize the timing of energetically costly processes by curtailing nonessential energetically demanding processes when environmental conditions are not favourable. One proximate environmental variable used to fine-tune moment-to-moment changes in reproductive physiology and behaviour is food intake. The neuroendocrine mechanisms by which food restriction leads to the cessation of reproduction in seasonally breeding rodent species remain largely unspecified. The present study sought to determine the effects of extended food restriction on the gonadotropin releasing hormone (GnRH) Neuronal System. Male prairie voles (Microtus ochrogaster) were either fed ad libitum or were exposed to either 1, 2 or 3 weeks of moderate (70% of daily mean) food restriction. In accordance with previous studies of food restriction, gross reproductive organ masses and body mass were unaffected by food deprivation. Although 1 week of food restriction did not result in alterations in the GnRH Neuronal System, food restriction for 2 weeks was associated with increased GnRH-immunoreactive (GnRH-ir) neurone soma size. Three weeks of food restriction resulted in a pronounced increase in GnRH-ir neurone numbers, as well as an increase in fibre intensity in the main fibre pathway to the median eminence. Taken together, these findings suggest that extended food restriction leads to modifications in the GnRH Neuronal System, providing a means for temporary cessation of reproduction without gross alterations in reproductive physiology. This transient change in the hypothalmo-pituitary-gonadal axis, without pronounced changes in reproductive organ morphology, likely provides a mechanism for the rapid reinitiation of breeding in nature when local conditions provide adequate food availability.

  • photoperiod and temperature interact to affect the gnrh Neuronal System of male prairie voles microtus ochrogaster
    Journal of Biological Rhythms, 2000
    Co-Authors: Lance J Kriegsfeld, N J Ranalli, Marie A Bober, Randy J Nelson
    Abstract:

    Individuals of numerous species limit energy expenditure during winter by inhibiting reproduction and other nonessential functions. To time these adaptations appropriately with the annual cycle, animals rely on environ- mental cues that predict, well in advance, the onset of winter. The most com- monly studied environmental factor that animals use to time reproduction is photoperiod. Rodents housed in short photoperiods in the laboratory or in natu- rally declining day lengths exhibit pronounced alterations in reproductive func- tion concomitant with alterations in the hypothalamic gonadotropin-releasing hormone Neuronal System. Because animals in their natural environment use fac- tors in addition to photoperiod to time reproduction, the present study sought to determine the independent effects of photoperiod and temperature, as well as the interaction between these factors, on reproductive parameters and the GnRH Neuronal System. Male prairie voles were housed in either long (LD 16:8) or short (LD 8:16) day lengths for 10 weeks. Animals in each photoperiod were further subdivided into groups housed in either mild (i.e., 20°C) or low (i.e., 8°C) temper- atures. As shown with immunohistochemistry, voles that underwent gonadal regression in response to short photoperiods and long-day voles housed in low temperatures (and maintained large gonads) exhibit higher GnRH- immunoreactive (GnRH-ir) neuron numbers in the preoptic area/anterior hypo- thalamus (POA/AH) relative to all other groups. In addition, voles that under- went gonadal regression in response to both short days and low temperatures did not exhibit an increase in GnRH-ir neuron numbers compared to long-day, mild-temperature controls. These data suggest that photoperiod and tempera- ture interact to influence reproductive function potentially by alterations of the GnRH Neuronal System.

  • photoperiod affects the gonadotropin releasing hormone Neuronal System of male prairie voles microtus ochrogaster
    Neuroendocrinology, 1999
    Co-Authors: Lance J Kriegsfeld, Randy J Nelson
    Abstract:

    In order to maximize survival, animals inhabiting temperate and boreal latitudes exhibit numerous adaptations to changing seasons. Central among this suite of coping strategies is the cessation of breeding during the suboptimal conditions of winter. Many nontropical rodents inhibit reproduction well in advance of winter in response to short day lengths. Male prairie voles (Microtus ochrogaster) are small temperate-zone rodents that vary in their reproductive response to photoperiod. Some male voles undergo complete gonadal regression during short days (responders) while others fail to inhibit reproduction when exposed to short day lengths (nonresponders). The neuroendocrine mechanisms regulating this differential response to photoperiod have not been investigated in this species. Presumably, photoperiod can act at any or all levels of the hypothalamo-pituitary-gonadal (HPG) axis to regulate reproduction. The present study sought to determine the contribution of the GnRH System to this variable reproductive response to photoperiod. Male prairie voles were housed in either long or short day lengths for 10 weeks. As shown with immunohistochemistry, voles that underwent gonadal regression in response to short photoperiods exhibited increased GnRH neuron numbers in the preoptic area/anterior hypothalamus (POA/AH) relative to both long-day animals and short-day voles that maintained reproductive function. Mean optical density of staining and cell size did not differ among groups. These data suggest that the differential reproductive response to photoperiod in male voles is mediated, in part, by alterations in the GnRH Neuronal System.

Haruko Uemura - One of the best experts on this subject based on the ideXlab platform.

  • neuropeptide y immunoreactive Neuronal System and colocalization with fmrfamide in the optic lobe and peduncle complex of the octopus octopus vulgaris
    Cell and Tissue Research, 2002
    Co-Authors: Hirohumi Suzuki, Miho Nakagawa, Toshiharu Yamamoto, Haruko Uemura
    Abstract:

    The distribution of neuropeptide Y (NPY)-like immunoreactivity and its colocalization with FMRFamide were investigated in the optic lobe and peduncle complex of the octopus (Octopus vulgaris) by using immunohistochemical techniques. In the optic lobe cortex, NPY-immunoreactive (NPY-IR) fibers were observed in the plexiform layer, although no NPY-IR somata were observed in the outer or inner granular cell layers. In the optic lobe medulla, NPY-IR somata were seen in the cell islands, and abundant NPY-IR varicose fibers were observed in the neuropil. Most of the NPY-IR structures in the medulla showed FMRFamide-like immunoreactivity. In the peduncle lobe, abundant NPY-IR and FMRFamide-IR (NPY/FMRF-IR) varicose fibers were seen in the basal zone neuropil of the peduncle lobe. In the olfactory lobe, NPY/FMRF-IR varicose fibers were also abundant in the neuropil of the three lobules. NPY/FMRF-IR somata, with processes running to various neuropils, were scattered in the median and posterior lobules. In the optic gland, many NPY/FMRF-IR varicose fibers formed a honeycomb pattern. These observations suggest that NPY/FMRF-IR neurons in the optic lobes participate in the modulation of visual information and that those in the optic gland are involved in the regulation of endocrine function.

  • galanin immunoreactive Neuronal System and colocalization with serotonin in the optic lobe and peduncle complex of the octopus octopus vulgaris
    Brain Research, 2000
    Co-Authors: Hirohumi Suzuki, Megumi Inenaga, Toshiharu Yamamoto, Haruko Uemura
    Abstract:

    Immunohistochemical techniques were used to investigate the distribution of galanin-like immunoreactivity and colocalization with serotonin (5-HT) in the optic lobe and peduncle complex of the octopus, Octopus vulgaris. Galanin immunoreactive (Gal-IR) fibers, but not cells, were seen in the plexiform layer of the optic lobe cortex. Gal-IR cells were scattered in the cell-islands of the optic lobe medulla and Gal-IR varicose fibers were observed to be abundant in the neuropil surrounding the islands. All Gal-IR cells were immunoreactive for 5-HT, and a few cells showed only 5-HT-like immunoreactivity. In the peduncle lobe, no Gal-IR cells were seen in the basal zone or spine, but in the basal zone, many Gal-IR fibers were seen. In the anterior olfactory lobule, only a few pyramidal Gal-IR cells were observed in the cell layer, and their apical processes were traced to the central neuropil. In the median olfactory lobule, ovoid Gal-IR cells were scattered in the peripheral cell layer. All Gal-IR cells in the anterior and median olfactory lobules showed 5-HT-like immunoreactivity. In the posterior olfactory lobule, ovoid and triangular Gal-IR cells were scattered in the cell layer. Some of them showed 5-HT-like immunoreactivity. Western blot analysis indicated an Gal-IR band at approximately 15.4 kDa. These results suggest the association of galanin-like substance and 5-HT with the visual System of octopus and that the main form of the octopus galanin might have a different molecular weight from vertebrate galanins.

Maddalena Mastrogiacomo - One of the best experts on this subject based on the ideXlab platform.

  • correction corrigendum simultaneous submicrometric 3d imaging of the micro vascular network and the Neuronal System in a mouse spinal cord
    Scientific Reports, 2015
    Co-Authors: Michela Fratini, Inna Bukreeva, Gaetano Campi, Francesco Brun, Giuliana Tromba, Peter Modregger, Domenico Bucci, Giuseppe Battaglia, Raffaele Spano, Maddalena Mastrogiacomo
    Abstract:

    Faults in vascular (VN) and Neuronal networks of spinal cord are responsible for serious neurodegenerative pathologies. Because of inadequate investigation tools, the lacking knowledge of the complete fine structure of VN and Neuronal System represents a crucial problem. Conventional 2D imaging yields incomplete spatial coverage leading to possible data misinterpretation, whereas standard 3D computed tomography imaging achieves insufficient resolution and contrast. We show that X-ray high-resolution phase-contrast tomography allows the simultaneous visualization of three-dimensional VN and Neuronal Systems of ex-vivo mouse spinal cord at scales spanning from millimeters to hundreds of nanometers, with nor contrast agent nor sectioning and neither destructive sample-preparation. We image both the 3D distribution of micro-capillary network and the micrometric nerve fibers, axon-bundles and neuron soma. Our approach is very suitable for pre-clinical investigation of neurodegenerative pathologies and spinal-cord-injuries, in particular to resolve the entangled relationship between VN and Neuronal System.

  • Simultaneous submicrometric 3D imaging of the micro-vascular network and the Neuronal System in a mouse spinal cord
    Scientific Reports, 2015
    Co-Authors: Michela Fratini, Inna Bukreeva, Gaetano Campi, Francesco Brun, Giuliana Tromba, Peter Modregger, Domenico Bucci, Giuseppe Battaglia, Raffaele Spano, Maddalena Mastrogiacomo
    Abstract:

    Faults in vascular (VN) and Neuronal networks of spinal cord are responsible for serious neurodegenerative pathologies. Because of inadequate investigation tools, the lacking knowledge of the complete fine structure of VN and Neuronal System represents a crucial problem. Conventional 2D imaging yields incomplete spatial coverage leading to possible data misinterpretation, whereas standard 3D computed tomography imaging achieves insufficient resolution and contrast. We show that X-ray high-resolution phase-contrast tomography allows the simultaneous visualization of three-dimensional VN and Neuronal Systems of ex-vivo mouse spinal cord at scales spanning from millimeters to hundreds of nanometers, with nor contrast agent nor sectioning and neither destructive sample-preparation. We image both the 3D distribution of micro-capillary network and the micrometric nerve fibers, axon-bundles and neuron soma. Our approach is very suitable for pre-clinical investigation of neurodegenerative pathologies and spinal-cord-injuries, in particular to resolve the entangled relationship between VN and Neuronal System

N J Ranalli - One of the best experts on this subject based on the ideXlab platform.

  • food restriction affects the gonadotropin releasing hormone Neuronal System of male prairie voles microtus ochrogaster
    Journal of Neuroendocrinology, 2001
    Co-Authors: Lance J Kriegsfeld, N J Ranalli, A G Trasy, Randy J Nelson
    Abstract:

    Individuals of species inhabiting temperate and boreal latitudes optimize the timing of energetically costly processes by curtailing nonessential energetically demanding processes when environmental conditions are not favourable. One proximate environmental variable used to fine-tune moment-to-moment changes in reproductive physiology and behaviour is food intake. The neuroendocrine mechanisms by which food restriction leads to the cessation of reproduction in seasonally breeding rodent species remain largely unspecified. The present study sought to determine the effects of extended food restriction on the gonadotropin releasing hormone (GnRH) Neuronal System. Male prairie voles (Microtus ochrogaster) were either fed ad libitum or were exposed to either 1, 2 or 3 weeks of moderate (70% of daily mean) food restriction. In accordance with previous studies of food restriction, gross reproductive organ masses and body mass were unaffected by food deprivation. Although 1 week of food restriction did not result in alterations in the GnRH Neuronal System, food restriction for 2 weeks was associated with increased GnRH-immunoreactive (GnRH-ir) neurone soma size. Three weeks of food restriction resulted in a pronounced increase in GnRH-ir neurone numbers, as well as an increase in fibre intensity in the main fibre pathway to the median eminence. Taken together, these findings suggest that extended food restriction leads to modifications in the GnRH Neuronal System, providing a means for temporary cessation of reproduction without gross alterations in reproductive physiology. This transient change in the hypothalmo-pituitary-gonadal axis, without pronounced changes in reproductive organ morphology, likely provides a mechanism for the rapid reinitiation of breeding in nature when local conditions provide adequate food availability.

  • photoperiod and temperature interact to affect the gnrh Neuronal System of male prairie voles microtus ochrogaster
    Journal of Biological Rhythms, 2000
    Co-Authors: Lance J Kriegsfeld, N J Ranalli, Marie A Bober, Randy J Nelson
    Abstract:

    Individuals of numerous species limit energy expenditure during winter by inhibiting reproduction and other nonessential functions. To time these adaptations appropriately with the annual cycle, animals rely on environ- mental cues that predict, well in advance, the onset of winter. The most com- monly studied environmental factor that animals use to time reproduction is photoperiod. Rodents housed in short photoperiods in the laboratory or in natu- rally declining day lengths exhibit pronounced alterations in reproductive func- tion concomitant with alterations in the hypothalamic gonadotropin-releasing hormone Neuronal System. Because animals in their natural environment use fac- tors in addition to photoperiod to time reproduction, the present study sought to determine the independent effects of photoperiod and temperature, as well as the interaction between these factors, on reproductive parameters and the GnRH Neuronal System. Male prairie voles were housed in either long (LD 16:8) or short (LD 8:16) day lengths for 10 weeks. Animals in each photoperiod were further subdivided into groups housed in either mild (i.e., 20°C) or low (i.e., 8°C) temper- atures. As shown with immunohistochemistry, voles that underwent gonadal regression in response to short photoperiods and long-day voles housed in low temperatures (and maintained large gonads) exhibit higher GnRH- immunoreactive (GnRH-ir) neuron numbers in the preoptic area/anterior hypo- thalamus (POA/AH) relative to all other groups. In addition, voles that under- went gonadal regression in response to both short days and low temperatures did not exhibit an increase in GnRH-ir neuron numbers compared to long-day, mild-temperature controls. These data suggest that photoperiod and tempera- ture interact to influence reproductive function potentially by alterations of the GnRH Neuronal System.