Twenty-Four-Hour Pattern of Growth Hormone Secretion in the Rhesus Monkey: Studies Including Alterations of the Sleep/Wake and Sleep Stage Cycles*

Abstract

The 24-h pattern of GH secretion and its possible relation to the sleep/wake cycle and to sleep stages were studied in 12 male rhesus monkeys. Blood samples were drawn every 15 min for 96 h, 24 h, or shorter periods of time through chronic right atrial catheters which extended through the wall into the adjacent room. In addition, activity rating (daytime) and determination of sleep stages from electroencephalogram recordings (nighttime) were done. GH profiles were obtained during undisturbed conditions and during deprivation of nap, 5 h total sleep, slow wave sleep (SWS), and rapid eye movement (REM) sleep. GH secretion was episodic, with peak concentrations often exceeding 20 ngeq/ml and nadirs mostly below 1 ngeq/ml. Autocorrelation analysis demonstrated a circadian and an ultradian rhythm during undisturbed conditions. However, the cycle length of the ultradian rhythm showed large inter- and intraindividual variations (from 3--6 h). Neither cross-correlation analysis between hormonal and activity/electroencephalogram sleep stage time series nor results of deprivation experiments produced evidence for a link between nap phases, the sleep/wake cycle, or the SWS/REM sleep stage cycle on the one hand and the GH secretory pattern on the other hand. However, while SWS deprivation was highly effective, REM deprivation did not substantially reduce total REM sleep time due to frequent entries into abortive REM sleep epochs. During the daytime, there was no significant correlation between activity/arousal and GH, but during the night, there was a significant positive correlation between stage waking and GH. A direct or indirect synchronizing effect of the matutinal light change is suggested by the pattern of the 24-h curve of mean GH concentrations during undisturbed conditions: a steep increase from very low concentrations at light onset, followed by a succession of nadirs and peaks at approximately 4.5-h intervals. However, the nadirs became progressively more shallow until there was no apparent periodicity during the night due to the loss of synchronization. It is concluded that GH in the rhesus monkey shows a circadian and an ultradian periodicity. However, in contrast to man, sleep and SWS are not important determinators of the 24-h GH pattern.

Correlation of growth hormone secretion to sleep in the immature rat.

“…A similar correlation was indicated in dogs, but only under unphysiological condition, as after sleep deprivation (Takahashi, Ebihara, Nakamura & Takahashi, 1981). Further, in non-human primates (baboon and rhesus monkey), conflicting results have been reported on either the spontaneous correlation or the effect of sleep deprivation (Parker, Morishima, Koerker, Gale & Goodner, 1972;Jacoby, Sassin, Greenstein & Weitzman, 1974;Jacoby, Smith, Sassin, Greenstein & Weitzman, 1975;Quabbe, Gregor, Bumke-Vogt, Eckhof & Witt, 1981). Considering the fact that extensive findings have been accumulated for the rat on the brain control sites of GH secretion including the functional relationship of these neural sites with the sleep mechanism (Frohman, Bernardis & Kant, 1968;Martin, 1972;Willoughby, Terry, Renaud & Brazeau, 1976b;Terry & Martin, 1981;Martin, Kontor & Mead, 1973), the present result may offer a great advantage in further investigation in the rat.…”

Dissociated 24-Hour Patterns of Somatotropin and Prolactin in Fatal Familial Insomnia

“…Maximal somatotropin release occurs within min utes of the onset of stage 3 or 4 sleep [12]. Delay or advancement in time of onset of deep sleep leads to simi lar time shifts in the nocturnal elevation of somatotropin [6,8,9,13,14], The same parallelism is maintained when the normal sleep-wake cycle is inverted, and sleepdeprived healthy subjects lose the nocturnal somatotropin rise [6,7,9,10]. A similar loss has been found in patients with suprahypothalamic (including bilateral thalamic) le- In each 24-hour recording session for the patients, and on the group averages over 30-min intervals for the control subjects, a Fourier series with six harmonics (periods of 24, 12, 8, 6, 4.8 and 4 h) was fitted to the data.…”

Orexins (hypocretins) actions on the GHRH/somatostatin‐GH axis

“…The ultradian secretion of GH is linked to the sleep–wake cycle (Quabbe et al. 1981, Kawakami et al.…”

“…1984, Kimura & Tsai 1984). A major peak of GH secretion happens during non‐REM sleep in humans and in some animal species (Quabbe et al. 1981, Kawakami et al.…”