Effect of luteinizing hormone-releasing hormone (LH-RH) on the multiunit activity of the arcuate nucleus in the proestrous rats.

Multiple Unit Activity (MUA) of the hypothalamic arcuate nucleus as indicated by discriminated spikes with window setting between 18-30 uV, the integrated MUA and the cortical EEG of the urethane anaesthetized rats on the proestrous day was recorded with the help of a polygraph. Infusion of LH-RH in the 3rd ventricle markedly increased the arcuate nucleus MUA. The effect started within minutes of infusion, peak came after 20-30 minutes and the activity remained increased for 3-4 hours. Saline infusion in the 3rd ventricle was ineffective. Feedback action of CSF-LH-RH to the arcuate nucleus for the regulation of LH-RH is suggested.