Regional Variation in γ‐Aminobutyric Acid Turnover: Effect of Castration on γ‐Aminobutyric Acid Turnover in Microdissected Brain Regions of the Male Rat
- 1 June 1993
- journal article
- research article
- Published by Wiley in Journal of Neurochemistry
- Vol. 60 (6), 2254-2264
- https://doi.org/10.1111/j.1471-4159.1993.tb03512.x
Abstract
This study compared the turnover of GABA neurons in different brain areas of the male rat and examined the effect of castration on GABA turnover in regions of the brain associated with the control of gonadotropin secretion. To estimate GABA turnover, GABA was quantified by HPLC in microdissected brain regions 0, 30, 60, 90, and 120 min after inhibition of GABA degradation by aminooxyacetic acid (100 mg/kg, i.p.). GABA accumulation was linear in all areas for 90 min (p < 0.01), and GABA turnover was estimated as the slope of the line formed by increased GABA concentration versus time, determined by linear regression. There was considerable regional variation both in the initial steady-state concentrations of GABA and in the rates of GABA turnover. Of 10 discrete brain structures, GABA turnover was highest in the medial preoptic nucleus and lowest in the caudate nucleus. Turnover times in the terminal fields of known GABAergic projection neurons ranged sevenfold, from 2.6 h in the substantia nigra to 0.4 h in the lateral vestibular nucleus. The effect of castration on GABA turnover in 13 microdissected brain regions was investigated by measuring regional GABA concentrations before and 30 min after injection of aminooxyacetic acid in intact rats or 2 or 6 days postcastration. Following castration, steady-state GABA concentrations were increased, and GABA turnover decreased in the diagonal band of Broca, the medial preoptic area, and the median eminence. GABA turnover increased in the medial septal nucleus and was unaffected in the cortex, striatum, and hindbrain. These results are consistent with the hypothesis that testosterone negative-feedback control of luteinizing hormone-releasing hormone involves steroid-sensitive GABAergic neurons in the rostral and medial basal hypothalamus.Keywords
This publication has 75 references indexed in Scilit:
- Effect on Luteinizing Hormone Secretion of GABA Receptor Modulation in the Medial Preoptic Area at the Time of Proestrous Luteinizing Hormone SurgeNeuroendocrinology, 1991
- Progestin receptor-containing cells in guinea pig hypothalamus: Afferent connections, morphological characteristics, and neurotransmitter contentMolecular and Cellular Neuroscience, 1990
- An improved and rapid HPLC-EC method for the isocratic separation of amino acid neurotransmitters from brain tissue and microdialysis perfusatesLife Sciences, 1988
- Preoptic Catecholamine, GABA, and Glutamate Release in Ovariectomized and Ovariectomized Estrogen-Primed Rats Utilizing a Push-Pull Cannula TechniqueNeuroendocrinology, 1985
- Glutamic Acid Decarboxylase-Containing Axons Synapse on LHRH Neurons in the Rat Medial Preoptic AreaNeuroendocrinology, 1985
- Postmortem increase of GABA levels in peripheral rat tissues: Prevention by 3-mercapto-propionic acidJournal of Neural Transmission, 1984
- Intracerebral injection of gamma vinyl GABA: Method for measuring rates of GABA synthesis in specific brain regionsLife Sciences, 1981
- Glutamate decarboxylase (GAD) and γ-aminobutyric acid (GABA) in discrete nuclei of hypothalamus and substantia nigraBrain Research, 1977
- A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye bindingAnalytical Biochemistry, 1976
- REGIONAL γ‐AMINOBUTYRIC ACID LEVELS IN RAT BRAIN DETERMINED AFTER MICROWAVE FIXATIONJournal of Neurochemistry, 1975