TEMPORAL RELATIONSHIP BETWEEN PROLACTIN SECRETION AND SLOW-WAVE ELECTROENCEPHALIC ACTIVITY DURING SLEEP

It is well established that plasma prolactin (PRL) concentrations exhi bit a sleep-dependent pattern, with the highest levels occurring durin g sleep and the lowest during waking. Still, controversy exists concer ning an association between rapid eye movement (REM) and non-REM sleep cycles and plasma PRL pulses. These studies were all based on convent ional scoring of sleep stages. In the present study, plasma PRL concen trations were analyzed at 10-minute intervals in 10 subjects during th e night when sleeping. PRL secretory rates were calculated by a deconv olution procedure. Spectral parameters of sleep electroencephalographi c (EEG) recordings were analyzed together with PRL secretion using cro ss-correlation. Slow-wave activity of the EEG and PRL secretion ran pa rallel in all individuals. Conversely, alpha and beta bands and the EE G mean frequency were inversely proportional to PRL secretion. In 9 of the 10 subjects studied, PRL secretion was concomitant with delta wav es or lagged behind by 10-20 minutes, depending on subjects, with maxi mum cross-correlation coefficients ranging between 0.40 and 0.67. This temporal relationship between PRL secretion and delta waves was furth er assessed by a pulse-by-pulse analysis based on the calculation of p robability levels after computer simulations. Nine of the 10 subjects displayed significant concomitance between delta wave activity and PRL secretory oscillations. These results demonstrate that PRL, secretion during sleep is coupled to delta waves in young healthy men.