How growth hormone released during sleep
Brain circuitry involved in the sleep dependent growth hormone (GH) release is not known.
The researchers show that increase in growth hormone release during both rapid eye movement (REM) and non-REM (NREM) sleep is driven by sleep-wake dependent activity of stimulatory GHRH neurons and inhibitory SST neurons in the hypothalamus.
They also demonstrate that SST neurons in the arcuate nucleus suppress GH release by inhibiting nearby GHRH neurons that stimulate GH release, whereas periventricular SST neurons inhibit GH release by projecting to the median eminence.
They also observed that the released growth hormone enhances the excitability of locus coeruleus noradrenergic neurons and promotes wakefulness, revealing an additional negative feedback pathway.
