Description
We examined the effects of GABAB receptor activation in the dentate gyrus of hippocampal slices prepared from 6-8-day-old rat pup. Baclofen (0.25-1.0 microM), a GABAB agonist, rapidly and potently disinhibited the developing dentate, similar to its effect in the mature organism. CGP 35348, a GABAB antagonist, quickly reversed the baclofen-induced disinhibition. However, GABAB antagonists did not reverse long-latency (500-1000 ms IPI) paired-pulse depression, suggesting that it is not caused by a late GABAB-mediated IPSP. GABAB-mediated disinhibition of the dentate gyrus can occur by postnatal day 6, providing a powerful mechanism for altering excitability in the developing hippocampus.
Subject
Animals; Baclofen/analogs & derivatives/pharmacology; Electric Stimulation; Evoked Potentials/drug effects; GABA-A Receptor Antagonists; GABA-A/drug effects/physiology; GABA-B Receptor Antagonists; GABA-B/*metabolism; Hippocampus/*growth & development/*metabolism; In Vitro Techniques; Organophosphorus Compounds/pharmacology; Rats; Receptors