scholarly journals Glutamatergic and GABAergic Innervation of Human Gonadotropin-Releasing Hormone-I Neurons

Endocrinology ◽  
2012 ◽  
Vol 153 (6) ◽  
pp. 2766-2776 ◽  
Author(s):  
Erik Hrabovszky ◽  
Csilla S. Molnár ◽  
Róbert Nagy ◽  
Barbara Vida ◽  
Beáta Á. Borsay ◽  
...  
Keyword(s):  
Glutamate Transporter ◽  
Vesicular Glutamate Transporter ◽  
Glutamatergic Neurons ◽  
Relative Contribution ◽  
Paraventricular Nuclei ◽  
Gnrh Neurons ◽  
Immunohistochemical Studies ◽  
Dual Label ◽  
Formalin Fixed ◽  
Afferent Control

Amino acid (aa) neurotransmitters in synaptic afferents to hypothalamic GnRH-I neurons are critically involved in the neuroendocrine control of reproduction. Although in rodents the major aa neurotransmitter in these afferents is γ-aminobutyric acid (GABA), glutamatergic axons also innervate GnRH neurons directly. Our aim with the present study was to address the relative contribution of GABAergic and glutamatergic axons to the afferent control of human GnRH neurons. Formalin-fixed hypothalamic samples were obtained from adult male individuals (n = 8) at autopsies, and their coronal sections processed for dual-label immunohistochemical studies. GABAergic axons were labeled with vesicular inhibitory aa transporter antibodies, whereas glutamatergic axons were detected with antisera against the major vesicular glutamate transporter (VGLUT) isoforms, VGLUT1 and VGLUT2. The relative incidences of GABAergic and glutamatergic axonal appositions to GnRH-immunoreactive neurons were compared quantitatively in two regions, the infundibular and paraventricular nuclei. Results showed that GABAergic axons established the most frequently encountered type of axo-somatic apposition. Glutamatergic contacts occurred in significantly lower numbers, with similar contributions by their VGLUT1 and VGLUT2 subclasses. The innervation pattern was different on GnRH dendrites where the combined incidence of glutamatergic (VGLUT1 + VGLUT2) contacts slightly exceeded that of the GABAergic appositions. We conclude that GABA represents the major aa neurotransmitter in axo-somatic afferents to human GnRH neurons, whereas glutamatergic inputs occur somewhat more frequently than GABAergic inputs on GnRH dendrites. Unlike in rats, the GnRH system of the human receives innervation from the VGLUT1, in addition to the VGLUT2, subclass of glutamatergic neurons.

scholarly journals The Existence of a Second Vesicular Glutamate Transporter Specifies Subpopulations of Glutamatergic Neurons

2001 ◽  
Vol 21 (22) ◽  
pp. RC181-RC181 ◽  
Author(s):  
Etienne Herzog ◽  
Gian Carlo Bellenchi ◽  
Christelle Gras ◽  
Véronique Bernard ◽  
Philippe Ravassard ◽  
...  
Keyword(s):  
Glutamate Transporter ◽  
Vesicular Glutamate Transporter ◽  
Glutamatergic Neurons

scholarly journals Hypophysiotropic Thyrotropin-Releasing Hormone and Corticotropin-Releasing Hormone Neurons of the Rat Contain Vesicular Glutamate Transporter-2

Endocrinology ◽  
2005 ◽  
Vol 146 (1) ◽  
pp. 341-347 ◽  
Author(s):  
Erik Hrabovszky ◽  
Gábor Wittmann ◽  
Gergely F. Turi ◽  
Zsolt Liposits ◽  
Csaba Fekete
Keyword(s):  
Glutamate Release ◽  
Glutamate Transporter ◽  
Microscopic Analysis ◽  
Male Rat ◽  
Confocal Laser ◽  
Vesicular Glutamate Transporter ◽  
Releasing Hormone ◽  
Large Numbers ◽  
Adult Male Rat ◽  
Dual Label

TRH and CRH are secreted into the hypophysial portal circulation by hypophysiotropic neurons located in parvicellular subdivisions of the hypothalamic paraventricular nucleus (PVH). Recently these anatomical compartments of the PVH have been shown to contain large numbers of glutamatergic neurons expressing type 2 vesicular glutamate transporter (VGLUT2). In this report we presented dual-label in situ hybridization evidence that the majority (>90%) of TRH and CRH neurons in the PVH of the adult male rat express the mRNA encoding VGLUT2. Dual-label immunofluorescent studies followed by confocal laser microscopic analysis of the median eminence also demonstrated the occurrence of VGLUT2 immunoreactivity within TRH and CRH axon varicosities, suggesting terminal glutamate release from these neuroendocrine systems. These data together indicate that the hypophysiotropic TRH and CRH neurons possess glutamatergic characteristics. Future studies will need to address the physiological significance of the endogenous glutamate content in these neurosecretory systems in the neuroendocrine regulation of thyroid and adrenal functions.

scholarly journals Distribution of Vesicular Glutamate Transporter-2 Messenger Ribonucleic Acid and Protein in the Septum-Hypothalamus of the Rat

Endocrinology ◽  
2003 ◽  
Vol 144 (2) ◽  
pp. 662-670 ◽  
Author(s):  
Winston Lin ◽  
Kyle McKinney ◽  
Liansheng Liu ◽  
Shruti Lakhlani ◽  
Lothar Jennes
Keyword(s):  
Glutamate Transporter ◽  
Brain Regions ◽  
Female Rats ◽  
Vesicular Glutamate Transporter ◽  
Excitatory Neurotransmitter ◽  
Adrenal Steroid ◽  
Messenger Ribonucleic Acid ◽  
Glutamatergic Neurons ◽  
Neurotransmitter Glutamate ◽  
Arcuate Nuclei

The excitatory neurotransmitter glutamate is involved in the control of most, perhaps all, neuroendocrine systems, yet the sites of glutamatergic neurons and their processes are unknown. Here, we used in situ hybridization and immunohistochemistry for the neuron-specific vesicular glutamate transporter-2 (VGLUT2) to identify the neurons in female rats that synthesize the neurotransmitter glutamate as well as their projections throughout the septum-hypothalamus. The results show that glutamatergic neurons are present in the septum-diagonal band complex and throughout the hypothalamus. The preoptic area and ventromedial and dorsomedial nuclei are particularly rich in glutamatergic neurons, followed by the supraoptic, paraventricular, and arcuate nuclei, whereas the suprachiasmatic nucleus does not express detectable amounts of VGLUT2 mRNA. Immunoreactive neurites are seen in very high densities in all regions analyzed, particularly in the preoptic region, followed by the ventromedial, dorsomedial, and arcuate nuclei as well as the external layer of the median eminence, whereas the mammillary complex does not exhibit VGLUT2 immunoreactivity. Many VGLUT2 immunoreactive fibers also contained synaptophysin, suggesting that the transporter is indeed localized to presynaptic terminals. Together, the results identify glutamatergic cell bodies throughout the septum-hypothalamus in region-specific patterns and show that glutamatergic nerve terminals are present in very large numbers such that most neurons in these brain regions can receive glutamatergic input. We examined the GnRH system as an example of a typical neuroendocrine system and could show that the GnRH perikarya are closely apposed by many VGLUT2-immunoreactive boutons, some of which also contained synaptophysin. The presence of VGLUT2 mRNA-containing cells in specific nuclei of the hypothalamus indicates that many neuroendocrine neurons coexpress glutamate as neurotransmitter, in addition to neuropeptides. These systems include the oxytocin, vasopressin, or CRH neurons as well as many others in the periventricular and mediobasal hypothalamus. The presence of VGLUT2 mRNA in steroid-sensitive regions of the hypothalamus, such as the anteroventral periventricular, paraventricular, or ventromedial nuclei indicates that gonadal and adrenal steroid can directly alter the functions of these glutamatergic neurons.

scholarly journals Elimination of glutamatergic transmission from Hb9 interneurons does not impact treadmill locomotion

2021 ◽  
Author(s):  
Lina M. Koronfel ◽  
Kevin C. Kanning ◽  
Angelita Alcos ◽  
Christopher E. Henderson ◽  
Robert M. Brownstone
Keyword(s):  
Motor Neurons ◽  
Neural Circuits ◽  
Glutamate Transporter ◽  
Homeobox Gene ◽  
Vesicular Glutamate Transporter ◽  
Glutamatergic Neurotransmission ◽  
Glutamatergic Transmission ◽  
Glutamatergic Neurons ◽  
Treadmill Locomotion

ABSTRACTThe spinal cord contains neural circuits that can produce the rhythm and pattern of locomotor activity. It has previously been postulated that a rhythmogenic population of glutamatergic neurons, termed Hb9 interneurons, contributes to this rhythmogenesis. The homeobox gene, Hb9, is expressed in these interneurons as well as motor neurons. We developed a mouse line in which cre recombinase activity is inducible in neurons expressing Hb9. We then used this line to eliminate vesicular glutamate transporter 2 from Hb9 interneurons, and found that there were no deficits in treadmill locomotion. We conclude that glutamatergic neurotransmission by Hb9 interneurons is not required for locomotor rhythmogenesis. The role of these neurons in neural circuits remains elusive.

scholarly journals Elimination of Glutamatergic Transmission From Hb9 Interneurons Does Not Impact Treadmill Locomotion

2021 ◽  
Author(s):  
Lina M Koronfel ◽  
Kevin C Kanning ◽  
Angelita Alcos ◽  
Christopher E Henderson ◽  
Robert M Brownstone
Keyword(s):  
Motor Neurons ◽  
Neural Circuits ◽  
Glutamate Transporter ◽  
Homeobox Gene ◽  
Vesicular Glutamate Transporter ◽  
Glutamatergic Neurotransmission ◽  
Glutamatergic Transmission ◽  
Glutamatergic Neurons ◽  
Treadmill Locomotion

Abstract The spinal cord contains neural circuits that can produce the rhythm and pattern of locomotor activity. It has previously been postulated that a rhythmogenic population of glutamatergic neurons, termed Hb9 interneurons, contributes to this rhythmogenesis. The homeobox gene, Hb9, is expressed in these interneurons as well as motor neurons. We developed a mouse line in which cre recombinase activity is inducible in neurons expressing Hb9. We then used this line to eliminate vesicular glutamate transporter 2 from Hb9 interneurons, and found that there were no deficits in treadmill locomotion. We conclude that glutamatergic neurotransmission by Hb9 interneurons is not required for locomotor rhythmogenesis. The role of these neurons in neural circuits remains elusive.

scholarly journals Elimination of glutamatergic transmission from Hb9 interneurons does not impact treadmill locomotion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lina M. Koronfel ◽  
Kevin C. Kanning ◽  
Angelita Alcos ◽  
Christopher E. Henderson ◽  
Robert M. Brownstone
Keyword(s):  
Motor Neurons ◽  
Neural Circuits ◽  
Glutamate Transporter ◽  
Homeobox Gene ◽  
Vesicular Glutamate Transporter ◽  
Glutamatergic Neurotransmission ◽  
Glutamatergic Transmission ◽  
Glutamatergic Neurons ◽  
Treadmill Locomotion

AbstractThe spinal cord contains neural circuits that can produce the rhythm and pattern of locomotor activity. It has previously been postulated that a population of glutamatergic neurons, termed Hb9 interneurons, contributes to locomotor rhythmogenesis. These neurons were identified by their expression of the homeobox gene, Hb9, which is also expressed in motor neurons. We developed a mouse line in which Cre recombinase activity is inducible in neurons expressing Hb9. We then used this line to eliminate vesicular glutamate transporter 2 from Hb9 interneurons, and found that there were no deficits in treadmill locomotion. We conclude that glutamatergic neurotransmission by Hb9 interneurons is not required for locomotor behaviour. The role of these neurons in neural circuits remains elusive.

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