AbstractThe electrophysilogical effects of luteinizing hormone‐releasing hormone (LHRH) on CA1 pyramidal cells were investigated utilizing intracellular recodings from the in vitro rat hippocampal slce preparation. Bath application of LHRH (10‐7‐10‐12M) resulted in several changes in the electrophysiological properties of CA1 neurons. LHRH induced a long‐lasting depolarization associated with increased input resitance, and decrease in the afterhyperpolarization associated with increased input resistance, ad decrease in the afterhyperpolarization (AHP) following a train of action potentials, and a reduction in accommodation of repetitive cell discharge. These effects were blocked by the synthetic LHRH antagonist [Ac‐δ‐Pro1, pCl‐D‐Phe2, D‐Trp3,6]‐LHRH. These findings provide electrophysiological evidence for the role of LHRH as a neurotransmitter/neuromodula