Volumes of neurons nuclei and nucleoli in hypothalamic suprachiasmatic nucleus (SCN) of male and females rats during different seasons of year in norm and on a background of the toxic stress caused by chloride of cadmium (2 mg/100 g weights of a body, daily, within 15 days, per os) are studied. The maximal volumes of neuron SCN nuclei observed during the summer period at males and autumn at female while the maximal volumes of nucleoli and the maximal the nucleolus/nucleus relation were in the winter at animals both of sex. Sexual differences in volumes of nuclei and nucleoli of SCN neurosecretory cells are characteristic only for "transitive" seasons spring and autumn, and morphometric parameters of females exceed those of males. Salt of cadmium leads to decrease in rhythmic activity of SCN, reducing volume of nucleoli in the winter and increasing its in summer at animals both of sex.

Functional status of hypothalamic suprachiasmatic nucleus (SCN) in dorsomedial and ventrolateral subregions and thyroid gland at white rats in conditions light and dark deprivations are investigated. Change of a photomode, especially dark deprivation, led to change of a ratio of a functional condition of different SCN subregions in comparison with natural illumination. The strengthened synthetic processes in a thyroid gland were observed without dependence from gender of animal. A degree of reaction investigated neuroendocrine components at females are expressed more strongly in comparison with males.

Peculiarities of the influence of cadmium salt on LP processes in a liver, kidneys, head brain, gonads and plasma of blood in winter and summer periods have been investigated on 53 rats. The rats were divided into control and experimental groups. During 15 days the solution CdCl2 (dose 2 mg/100 g) was entered into the rats. The contents of LP products was determined by means of a assay kit ТBA-Agate. In winter the contents of ТBA-reagents in the brain and liver is higher in animal both two sexes, and in gonads is higher in males, in kidneys in females. The contents of LP products in females is higher in the liver and lower in gonads. In summer in females the level of МDА was higher in plasma of blood, and winter in kidneys. The introduction of CdCl2 results in increase in the level of МDА in the liver in the summer period, and in ovaries in winter. In males the level of МDА decreases in plasma of blood in summer.

The morpho-functional condition of supraoptical and paraventricular nuclei of hypothalamus peptide system of males and females of white rats in the conditions of cadmium intoxication during the most contrasting seasons of the year, winter and summer, is considered in the paper. The general mechanisms of reorganizations of hypothalamus large cell nuclei are revealed. The activity of supraoptical and paraventricular nuclei of hypothalamus of both sexes was considerably higher during the winter period in comparison with summer. Sexual differences of control animals were observed only in supraoptical nucleus and only during the winter period, thus, the functional activity in nucleus of males was higher. The chronic intoxication by chloride of cadmium has led to decrease in the functional activity of neurosecretion cells both supraoptical and paraventricular nuclei -at males in a greater degree in summer, and at females in winter.

The morphofunctional state of adrenal glands of white rat males and females in conditions of cadmium intoxications during the winter and summer periods has been examine. It has been revealed that the examined animals have sexual distinctions both in total area of adrenal glands and in the sizes of their zones. As a rule, the area of adrenal glands zones of females was larger. These intense distinctions were shown especially during the winter period. The analysis of seasonal distinctions of the area of male adrenal glands during the winter and summer periods has not been revealed the essential differences. The index of weight of female adrenal glands of the examined animals was considerably higher. Introduction of cadmium salt leads to increasing in the size of adrenal glands and the index of the body of the animals of both sexes, without dependence on the season of the year and causes higher tension of the functional activity of the males in the winter period, while tension of functional activity of the females is higher in the summer period.

The influence of cadmium salt in a dose 2 mg/100 g of body weight on the sizes of adrenal glands zones in winter (January) and in summer (July) seasons of the year is tested on white rats Rattus norvegicus. It was established, that the area of adrenal glands of the test females was higher than that of males, especially in winter. Cadmium salt exposure in summer resulted in increasing of the adrenal gland's area of males at the expense of increase of the area of cortical substance, as for females the area of both medullary and cortical zones was augmented. In winter the reaction to cadmium exposure is shown in increase of cortical substance of females, and as for males it is shown in increase of both cortical and medullary substance. Thus, the development of toxic stress, caused by the introduction of cadmium salt, of males takes place in greater degree in winter, and as for females it takes place in summer.

The influence of cadmium chloride on outbred white rats both male and female in winter and summer periods is investigated. Cadmium was entered daily intraventricularly in concentration 2 mg per 100 g of body weight within 15 days. The introduction of cadmium salt results in an increase of peroxide radical production in a liver of animals of both sexes in summer period. The introduction of the same dose in winter period does not result in change of peroxide product quantity in a liver, but it increases their number in female ovaries. In gonads of intact males the number of peroxide products is higher than in gonads of intact females, however, in other organs the number of TBA-reactants is higher than of females. The intensity of lipid peroxide oxidation depends on the season of a year. In winter the number of TBA-reactants is higher than of animals of both sexes

It is established that there are essential changes in the reproductive system by an old age. They are shown in the disturbance of cyclic function of ovaries that may lead to decline in genital function. Vitamin E takes a special place among the substances capable to slow down age processes and to regulate functional activity of the reproductive system. However injecting the vitamin to already grown old animals does not cause any essential changes of cyclic functions of gonads.