Yosypenko V. Ontogenetic Features of the Anterior Hypothalamus Structure in Rats under Photoperiod Modification

For the first time in the course of the experiment the ratio between amino and carboxyl groups in the content of proteins (R/B coefficient) in the hypothalamic LPNs neurons of mature and old rats was found under photoperiod modification. The results of our research enabled to conclude that R/B coefficient in the hypothalamic LPNs neurons of mature rats on an average is considerably higher than in old rats (p<0,001). The data obtained are indicative of the fact that proteins of the hypothalamic LPNs neurons of mature rats contain proteins more saturated with carboxyl groups than those of old rats. It may be indicative of more pronounced processes of protein oxidation modification in old rats. Light regimen modification produces various effects on the parameters of R/B coefficient in the hypothalamic LPNs neurons of mature and old rats. Thus, under conditions of light deprivation R/B coefficient in the hypothalamic LPNs neurons of mature and old rats does not change on an average. At the same time, light stimulation results in the increase of R/B coefficient in the hypothalamic LPNs neurons both in mature and old rats (p<0,001). The results obtained can be interpreted as the increase in the intensity of protein oxidation modification processes in the hypothalamic LPNs neurons in response to light regimen modification. For the first time the effect of melatonin as an experimental therapy of the deviation found was determined. Thus, exogenous melatonin injection in the ground of continuous light results in normalization of R/B coefficient in the hypothalamic LPNs neurons. This effect is more obvious for old rats, since a complete normalization of R/B coefficient mean values occurred in their hypothalamic LPNs neurons, but it was less obvious for mature rats (p<0,001). For the first time submicroscopic character of the architectonic reconstruction of the hypothalamic LPNs neurons of old rats was analyzed under light regimen modification. The results of our investigation of the hypothalamic LPNs cells of the experimental animals found their relative increased functional activity at a dark period of the day. Changes of the light regimen leads to disorders in the architectonics of the LPNs neurons manifested by pronounced hypertrophic and initial destructive changes of the nuclei and organelles of the hypothalamic LPNs neurons. More substantial ultramicroscopic changes in the structural organization of the hypothalamic LPNs neurons were found in rats kept under conditions of light stimulation than those kept under light deprivation, which is confirmed by the changes of the nerve cell ultrastructure at 2 a.m. and appearance of “dark” cells. When exogenous melatonin is used in the ground of twentyfourhour light, a relative normalization of the submicroscopic state of the hypothalamic LPNs cells is determined, though ultrastructure of organelles of synthetic and energy supply is found to be exhausted under a long light period. The results of the experimental studies conducted have added to the conception concerning histological, morphometric, histochemical and submicroscopic organization of one of the key elements in the regulation of the sleepwake cycle – the hypothalamic LPNs. The character of changes of the structures examined in ontogenesis and during light regimen modification is established, which is an important thing to understand the mechanisms of occurrence and development of sleep disorders and desynchronosis. It enables to improve early diagnostics, treatment and prevention of these pathological conditions. The data of the research enable to scientifically substantiate melatonin use in chronopathological conditions and sleep disorders.