GABA augments basal and electrically stimulated 3H-norepinephrine release in hypothalamic, preoptic area and cortical slices of female rats

• Published in: Neurochemistry international 1997-12, Vol.31 (6), p.769-780
• Main Authors: Fiber, Jeannie M., Etgen, Anne M.
• Format: Article
• Language: English
• Subjects: Animals; Basal Metabolism; Biological and medical sciences; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Cerebral Cortex - metabolism; Electric Stimulation; Female; Fundamental and applied biological sciences. Psychology; gamma-Aminobutyric Acid - physiology; Hypothalamus - metabolism; In Vitro Techniques; Norepinephrine - metabolism; Preoptic Area - metabolism; Rats; Rats, Sprague-Dawley; Tritium; Vertebrates: nervous system and sense organs
• ISSN: 0197-0186; 1872-9754
• DOI: 10.1016/S0197-0186(97)00036-3

These studies examined the regulation by GABA of norepinephrine release from hypothalamus, preoptic area and frontal cortex. Using superfused brain slicesfrom female rats, we show that 100 μM GABA enhances both basal and electrically stimulated release of 3H-norepinephrine in all three brain regions. The GABA A agonist muscimol (100 μM) significantly augments 3H-norepinephrine release, but it is somewhat less effective than GABA. The GABA B agonist baclofen has little or no effect on basal 3H-norepinephrine efflux. GABA also augments both the magnitude and duration of electrically evoked 3H-norepinephrine release in slices from all three brain regions. GABA facilitation of electrically stimulated 3H-norepinephrine release is mediated through GABA A receptors as evidenced by its blockad by 10 μM bicuculline, a GABA A antagonist, but not by 200 μM 2-OH-saclofen, a GABA B antagonist. These data show that the inhibitory amino acid neurotransmitter GABA enhances both basal and evoked release of 3H-norepinephrine in brain slices from female rats. These effects are predominantly mediated by GABA A receptors. GABA modulation of hypothalamic norepinephrine release may play a role in the regulation of gonadotropin secretion and reproductive behaviors such as lordosis.