Multiple unit activities recorded from the medial preoptic area during copulatory behavior in freely moving male rats.
Multiple unit activities (MUAs) were recorded from the medial preoptic area (MPO) during copulatory behavior in freely moving male rats. The baseline firing rate in the male MPO was 19.6 spikes/s +/- 7.1 S.E. (n = 14), and it was increased by 36.7% when a female rat was introduced (26.8 spikes/s +/- 8.9 S.E., n = 14). The firing rate remained elevated until ejaculation. The maximum firing rate (53.5 spikes/s +/- 16.7 S.E., n = 14) was obtained specifically during pursuit-mounting behavior. This high frequency firing with pursuit-mounting behavior was, however, immediately inhibited for 8.2 s +/- 2.1 S.E. (n = 14) when mounting was followed by intromission. The firing-inhibition was further prolonged (120.9 s +/- 44.6 S.E., n = 14) when ejaculation was performed after mounting and intromission. In cases where mounting was elicited alone, a firing-inhibition was not observed and the firing rate after mounting returned to the average firing rate during copulatory behavior. These results suggest that the MPO neurons may play a major role in pursuit-mounting, intromission and ejaculation.
D000200:Action Potentials; D000818:Animals; D003307:Copulation / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D011301:Preoptic Area / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology*