AGE SPECIFICS OF THE MORPHOMETRIC STATE OF LATERAL PREOPTIC NUCLEUS OF THE HYPOTHALAMUS UNDER DIFFERENT DURATION OF PHOTOPERIOD

Bulyk R. Ye., Yosypenko V. R., Vlasova K. V.

MORPHOLOGY

Scentific article

Abstract. Sleep is a complex physiological process regulated by homeostatic and circadian processes that involve various neural structures. The lateral preoptic nucleus of the hypothalamus plays a key role in the regulation of the sleep-wake cycle. The article analyzes the results of own histological and morphometric studies of neurons of the lateral preoptic nucleus of the hypothalamus of mature and old rats in conditions of different duration of the photoperiod. The location of the lateral preoptic nucleus of the hypothalamus is not completely symmetrical, both nuclei are undoubtedly present one in each hemisphere of the brain, but one of them is slightly in front of the other. The nucleus in the sections had a spherical or oval shape, and the neurons were of the same type both in the center and on the periphery of the nucleus. By stained with hematoxylin and eosin at high magnifications, it was seen that the neurons of the lateral preoptic nucleus of the hypothalamus had a dark oval or polygonal nucleus, often with acute angles, and the cytoplasm, in contrast, was light, almost transparent. Morphometric data indicate that the studied parameters (mean neurocyte volume, mean neurocyte nucleus volume, the nuclear-cytoplasmic ratio in neurocytes, and mean neurocyte count in the standard plane of the histological section) did not show clear differences in mean trends. This suggests that they do not respond significantly to changes in lighting conditions and time of day when the experiment was conducted, which requires a deeper search and study of morphological methods that can detect the response of neurons of lateral preoptic nucleus of the hypothalamus to changes in lighting. At the same time, it is noteworthy that in older rats compared to mature ratsthe number of neurons (about 30%) per unit area of the histological section decreases, the volume of neurons reduces by reducing the volume of their cytoplasm with a corresponding increase in nuclear-cytoplasmic ratio (nuclear-cytoplasmic coefficient).

sleep-wake cycle, lateral preoptic nucleus of the hypothalamus, circadian rhythms, photoperiod.

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«Bulletin of problems biology and medicine» Issue 2 (160), 2021 year, 197-200 pages, index UDK 611.814.1.068:591.44:599.323.452

10.29254/2077-4214-2021-2-160-197-200