Rapid eye movement (REM) sleep deprivation leads to an induction of galanin
gene expression in the rat brain, especially in the hypothalamus. Galanin
affects neuroendocrine systems that are involved in sleep regulation, i.e.
the growth hormone-releasing hormone-dependent system of the hypothalamus a
nd the locus coeruleus. In the study reported here we investigated the effe
cts of 4 x 50 mu g galanin (n = 10) and of 4 x 150 mu g galanin (n= 8) admi
nistered hourly between 22.00 and 01.00 h as intravenous boluses on the sle
ep EEG and nocturnal hormone secretion in healthy young men. Galanin admini
stration significantly increased REM sleep in the third sleep cycle with no
difference between the two doses. Spectral analysis revealed a significant
increase in the EEG power in the delta and theta frequency range for the t
otal night after the lower dose of galanin, but not after the higher dose.
The secretion of growth hormone, cortisol and prolactin remained unchanged
during sleep in both cases. Our data are consistent with the assumption of
a functional resemblance between the effect of galanin and that of REM slee
p deprivation, which is known to have antidepressive efficacy. (C) 1999 Els
evier Science Ltd. All rights reserved.