Sleep-dependent surges in growth hormone do not contribute to sleep-dependent memory consolidation.
In the search for the mechanisms that mediate the effects of sleep on the consolidation of memories, growth hormone (GH) recently became of interest, because in humans it is released mainly during slow-wave sleep (SWS), a period of enhanced declarative memory consolidation. In addition, recent studies showed that GH is involved in proper memory function in GH deficient and elderly humans and this effect has been linked to regulatory influences of GH on hippocampal NMDA receptors. Here, we blocked GH secretion by intravenous infusion of somatostatin in healthy young subjects during the first 3 h of sleep, which contain mainly SWS. Declarative and procedural memory consolidation was tested across this period, using a word pair association task and a mirror tracing task, respectively. Although GH was effectively suppressed, memory performance as well as sleep were entirely unaffected by this suppression. Whereas GH may in the long run generally support brain systems required for maintaining proper memory function, our data exclude a necessary contribution of the nocturnal surge in pituitary GH secretion to the acute processing and formation of specific memories during sleep.
Gais
Steffen
S
Department of Neuroendocrinology, University of Lübeck, Ratzeburger Allee 160, Hs. 23a, 23538 Lübeck, Germany. gais@kfg.uni-luebeck.de
Hüllemann
Philipp
P
Hallschmid
Manfred
M
Born
Jan
J
D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology; D013006:Growth Hormone / Q000187:drug effects / Q000378:metabolism*; D006728:Hormones / Q000008:administration & dosage; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009048:Motor Skills / Q000187:drug effects / Q000502:physiology; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D013004:Somatostatin / Q000008:administration & dosage / Q000502:physiology; D014706:Verbal Learning / Q000187:drug effects / Q000502:physiology*
D006728:Hormones; D013004:Somatostatin; D013006:Growth Hormone