Sleep deprivation increases somatostatin and growth hormone-releasing hormone messenger RNA in the rat hypothalamus.

We studied the effect of sleep deprivation (SD) on the amount of somatostatin (SRIF) and growth hormone-releasing hormone (GHRH) mRNA in rat hypothalamic nuclei. According to earlier studies SRIF possibly facilitates 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. Undisturbed rats sacrificed at the same time as the SD rats served as controls. After oligonucleotide in situ hybridization the amount of SRIF and GHRH mRNA was measured in brain sections by image analysis and cell count. SD increased the amount of SRIF mRNA in the arcuate nucleus (ARC). In 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 hypothalamic 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 and GHRH cells in PA are modulated by sleep loss, which is in accordance with the possible sleep regulatory function of these neuropeptides.

Sleep deprivation increases brain serotonin turnover in the rat.

IN order to study possible time-dependent changes in serotonin metabolism in rat brain, male Wistar rats were subjected to 3, 6 or 12 h total sleep deprivation (SD) by gentle handling. In addition two groups of rats subjected first to 6 h SD were allowed 2 or 4 h rebound sleep. Tissue concentrations of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were measured from several brain areas using HPLC/ECD. SD significantly increased the 5-HIAA/5-HT ratio in frontal cortex, hippocampus, hypothalamus and brain stem, indicating increased 5-HT turnover in those areas. After 2 and 4 h rebound sleep, the 5-HIAA/5-HT ratio was similar to that in controls. We conclude that a short SD increases 5-HT turnover in the rat brain for the duration of SD only.

The effect of REM sleep deprivation on somatostatin and growth hormone-releasing hormone gene expression in the rat hypothalamus.

Growth hormone-releasing hormone (GHRH) and somatostatin (SRIF) have been implicated as sleep factors. We studied how the hypothalamic SRIF/GHRH system is affected by possible feedback regulation resulting from REM sleep deprivation at the level of gene expression and how this is reflected in serum growth hormone (GH) content. Male rats were deprived of REM sleep on small platforms for 24 or 72 h, and one group was allowed a rebound sleep of 24 h after 72 h deprivation. Animals maintained on large platforms and animals taken directly from their home cages served as controls. In situ hybridization was made from 20 microm cryosections through the periventricular, paraventricular and arcuate hypothalamic nuclei using oligonucleotide probes for GHRH and SRIF. The number of cells expressing SRIF or GHRH was counted. Serum GH was measured by means of radioimmunoassay in similarly treated rats. Fewer cells expressed GHRH in the paraventricular nucleus of animals subjected to 24 and 72 h of REM sleep deprivation than in home control animals. A similar trend was observed in the arcuate nucleus. The number of cells expressing SRIF was elevated in the arcuate nucleus after 24 h of REM sleep deprivation but not after 72 h. In the periventricular nucleus the number of cells expressing SRIF was higher after 72 h of deprivation when compared to expression in animals maintained on large platforms. Serum GH levels were decreased in animals maintained on either small or large platforms. It is concluded that the expression of the SRIF and GHRH genes is modulated by REM sleep deprivation.

Sleep deprivation increases brain serotonin turnover in the Djungarian hamster.

Djungarian hamsters well adapted to a short photoperiod were subjected to 4 h of total sleep deprivation (SD) by gentle handling. Tissue concentrations of monoamines and of their metabolites were measured from several brain areas using HPLC with electrochemical detection. The 5-hydroxyindoleacetic acid/5-hydroxytryptamine (5-HIAA/5-HT) ratio was significantly increased after SD in the hippocampus, hypothalamus and brain stem, indicating increased serotonin (5-HT) turnover in those areas, while no changes were found in the frontal cortex and olfactory bulb. Dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) concentrations were elevated in the hypothalamus, while the noradrenaline concentrations did not change in any of the measured areas. We conclude that a short SD, which has been shown to elevate EEG slow-wave activity during recovery sleep, specifically increases 5-HT turnover in the brain.

REM sleep deprivation induces galanin gene expression in the rat brain.

Rats were deprived of REM sleep for 24 h by keeping them on small platforms that were placed in a water bath (the platform method). Galanin coding mRNA was visualized using in situ hybridization, and cells expressing galanin mRNA were counted. In REM sleep-deprived animals the cell count was higher in the preoptic area and periventricular nucleus. Lesions of this area have been reported to induce wakefulness in cats and rats. Galanin administered into the lateral ventricle had no effect on sleep. We conclude that REM sleep deprivation can induce galanin gene expression in some brain areas, but galanin alone does not modify spontaneous sleep.

The World Health Organization and International Atomic Energy Agency second interlaboratory comparison study in 16 countries on quality performance of nuclear medicine imaging devices.

Sixteen European countries participated in this WHO-IAEA intercomparison for which transmission CAP (College of American Pathologists) thyroid and IAEA-WHO liver phantoms were used. A total of 257 laboratories submitted 428 image evaluation reports. Overall results showed differences in performance between the various countries but similarities in performance for two gamma camera subgroups defined by year of manufacture, before and after 1980. A unique review of current European liver imaging practice is presented in terms of technical parameters, imaging conditions and evaluation procedures, and quality control procedures. The WHO-IAEA intercomparison demonstrated the need to establish new, or to improve the existing, quality control programmes in certain countries. However, the large number of participating laboratories, 257 compared with 70 in the previous WHO study, (Volodin et al. 1985), shows that these international studies are serving a useful purpose in promoting quality control in nuclear medicine imaging laboratories.