CLOMIPRAMINE-INDUCED SLEEP DISTURBANCE DOES NOT IMPAIR ITS PROLACTIN-RELEASING ACTION

The present study was undertaken to examine the role of sleep disturba nce, induced by clomipramine administration, on the secretory rate of prolactin (PRL) in addition to the direct drug effect. Two groups of s upine subjects were studied under placebo-controlled conditions, one d uring the night, when sleeping (n=7) and the other at daytime, when aw ake (n=6). Each subject received a single 50 mg dose of clomipramine g iven orally 2 hours before blood collection. Plasma PRL concentrations were analysed at 10 min intervals and underlying secretory rates calc ulated by a deconvolution procedure. For both experiments the drug int ake led to significant increases in PRL secretion, acting preferential ly on tonic secretion as pulse amplitude and frequency did not differ significantly from corresponding control values. During the night clom ipramine ingestion altered the complete sleep architecture in that it suppressed REM sleep and the sleep cycles and induced increased wakefu lness. As the relative increase in PRL secretion expressed as a percen tage of the mean did not significantly differ between the night and da y time studies (46+/-19% vs 34+/-10%), it can be concluded that the ob served sleep disturbance did not interfere with the drug action per se . The presence of REM sleep was shown not to be a determining factor e ither for secretory pulse amplitude and frequency, as, for both, mean nocturnal values were similar with and without prior clomipramine inge stion.