SLEEP-DEPRIVATION INCREASES SOMATOSTATIN AND GROWTH HORMONE-RELEASINGHORMONE MESSENGER-RNA IN THE RAT HYPOTHALAMUS

We studied the effect of sleep deprivation (SD) on the amount of somat ostatin (SRIF) and growth hormone-releasing hormone (GHRH) mRNA in rat hypothalamic nuclei. According to earlier studies SRIF possibly facil itates REM sleep and GHRH slow-wave sleep. Adult male rats were sleep deprived by the gentle handling method either for 6 h during the first half of the light phase or for 12 h during the dark phase. Undisturbe d rats sacrificed at the same time as the SD rats served as controls. After oligonucleotide in situ hybridization the amount of SRIF and GHR H mRNA was measured in brain sections by image analysis and cell count . SD increased the amount of SRIF mRNA in the arcuate nucleus (ARC). I n the periventricular nucleus (PE) there was no effect. The amount of GHRH mRNA increased in the paraventricular nucleus (PA) in the 6 h SD group but no effect was detected in ARC. In the periventromedial hypot halamic area (pVMH) the amount of GHRH mRNA was higher in the control rats sacrificed in the morning (09.00 hours) than in the afternoon (15 .00 hours), and SD had no effect. We conclude that SRIF cells in ARC a nd GHRH cells in PA are modulated by sleep loss, which is in accordanc e with the possible sleep regulatory function of these neuropeptides.