Steroid influences on GABAergic neurotransmission: A behavioral and biochemical approach
Steroid influences on GABAergic neurotransmission are varied and complex. However, there has been little investigation into the behavioral relevance of steroid effects on GABA. GABA had been implicated in the control of lordosis, a steroid dependent posture exhibited by sexually receptive female rats, but with conflicting results. This data demonstrated that GABA plays a dual role in the regulation of lordosis; stimulation of GABAergic transmission in the medial hypothalamus enhances lordosis whereas stimulation of GABA in the preoptic area inhibits lordosis. In separate experiments it was determined that progesterone enhances binding of the GABA{sub A} agonist, muscimol, in an in vitro exchange assay utilizing synaptic membranes prepared from the hypothalamus of ovariectomized rats. Scatchard analysis revealed a difference in affinity of the GABA{sub A} receptor between ovariectomized, receptive and post receptive females. In the preoptic area there was a significant decrease in the binding of {sup 3}H-muscimol in receptive females versus post-receptive and ovariectomized rats. In other behavioral experiments, the influence of estrogen and progesterone on GABA-induced analgesia was assessed. Intrathecal infusion of a low dose of muscimol at the lumbar level of the spinal cord did not alter nociceptive thresholds in ovariectomized rats. However, when intact females were administered the same dose of muscimol, they exhibited differential responses over the estrous cycle. Females in estrus were analgesic after muscimol, whereas diestrus females did not differ from ovariectomized controls. Ovariectomized rats injected s.c. with progesterone (2mg) exhibited a pronounced analgesia after intrathecal muscimol beginning 15 minutes after steroid treatment, whereas similar treatment with estrogen (10ug) was without effect.
- Research Organization:
- Rutgers--the State Univ., Newark, NJ (United States). Dept. of Chemistry
- OSTI ID:
- 5476307
- Country of Publication:
- United States
- Language:
- English
Similar Records
Colonic transit in rats: effect of ovariectomy, sex steroid hormones, and pregnancy
Estrogen-dependent expression of sine oculis homeobox 1 in the mouse uterus during the estrous cycle
Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
AMINOBUTYRIC ACID
ANIMAL CELLS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BEHAVIOR
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
DRUGS
ELECTROPHYSIOLOGY
ESTROGENS
ESTROUS CYCLE
HORMONES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KETONES
KINETICS
MAMMALS
MEMBRANES
NERVE CELLS
NEUROREGULATORS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHYSIOLOGY
PREGNANES
PROGESTERONE
RATS
REACTION KINETICS
RODENTS
SOMATIC CELLS
STEROID HORMONES
STEROIDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES