EFFECTS OF A BIOLOGICALLY-ACTIVE LHRH FRAGMENT ON CA1 HIPPOCAMPAL-NEURONS

The actions of a behaviorally active luteinizing hormone-releasing hor mone fragment, Ac-LHRH(5-10), on CA1 pyramidal cells were studied util izing conventional intracellular recordings from the in vitro rat hipp ocampal slice preparation. The behaviorally active fragment (10(-7) M) and the natural decapeptide [LHRH(1-10), 10(-8) M] had similar action s on CA1 neurons: a long-duration depolarization associated with incre ased input resistance, a reduction in the slow afterhyperpolarization (AHP), and a decrease in accommodation. In contrast, a biologically in active LHRH fragment [LHRH(1-6) at 10(-7) M] had no effect on electric al properties of CA1 neurons. These data suggest that Ac-LHRH(5-10), l ike LHRH(1-10), may have a modulatory action on hippocampal neurons.