EFFECT OF PRIOR NICOTINE TREATMENT ON DRUG-INDUCED CHANGES IN SERUM LH CONCENTRATIONS IN RATS

The effect of daily injections of nicotine on drug induced changes in LH secretion was investigated in male rats. Daily administration of ni cotine for 7 days resulted in decreased basal serum LH concentrations. Nicotine treatment blocked naloxone induced LH release and reduced LH RH induced increases in serum LH. Clonidine induced increases in serum LH were not altered by nicotine treatment and haloperidol treatment d id not alter nicotine induced decreases in serum LH. In an acute study nicotine blocked LH secretion induced by the long acting opioid antag onist naltrexone. Collectively these results indicate that opioidergic neurons are involved in the reduction in serum LH that occurs followi ng nicotine. They also indicate that chronic nicotine treatment can re duce the pituitary gland response to LHRH.