SEXUALLY DIMORPHIC PERFORANT PATH LONG-TERM POTENTIATION (LTP) IN URETHANE-ANESTHETIZED RATS

Sex differences in perforant path long-term potentiation (LTP) have be en reported in pentobarbital-anesthetized rats. Because this effect ma y be due to the prominent sex difference in barbiturate sensitivity, t he present report examined perforant path-dentate granule cell synapti c transmission and long-term potentiation (LTP) in adult male and fema le rats anesthetized with urethane. Spectral analysis of hippocampal e lectroencephalographic (EEG) activity indicated that urethane induced similar levels of anesthesia in male and female rats, and there were n o sex differences in the latency or amplitude of extracellular field p otentials evoked in the dentate gyrus following perforant path stimula tion. In contrast, there was a robust sex difference in the magnitude of LTP induced in the dentate gyrus following high-frequency stimulati on (HFS) of the perforant path. This sex difference in LTP was paralle led by a sex difference in the magnitude of N-methyl-D-aspartate (NMDA ) receptor activation generated by perforant path I-IFS. These results demonstrate a sex difference in hippocampal LTP that cannot be explai ned by a sex difference in level of anesthesia.