(638.7) The effect of photoperiod on the serotoninergic system of the thymus and its role in implementing the effects of exogenous melatonin

Poster Board Number: C133
Introduction: AAA has separate poster presentation times for odd and even posters.
Odd poster #s – 10:15 am – 11:15 am
Even poster #s – 11:15 am – 12:15 pm

Elena Luzikova (FSBEI of HE "I. N. Ulianov Chuvash State University"), Valentina Sergeeva (FSBEI of HE "I. N. Ulianov Chuvash State University"), Pavel Sergeev (FSBEI of HE "I. N. Ulianov Chuvash State University"), Ivan Lukachev (FSBEI of HE "I. N. Ulianov Chuvash State University")

Serotonin-containing cells of the thymus in Wistar rats were studied, which were kept during 4 weeks of the experiment under the conditions of a natural photoperiod, under the conditions of constant blackout, under the conditions of continuous illumination. The effect of melatonin ("Melaxen" Unipharm, Inc., USA) ad libitum at a concentration of 4 mg / liter with drinking for four weeks) on serotonin-positive cells of the thymus was studied. Results. The absence of light does not affect serotonin synthesis in the amine-producing cells of the diffuse endocrine system in the border of the cortical and medullary lobules, but it suppresses the amine-absorbing properties in the cortical substance cells of the thymus lobules. Continuous illumination does not affect the amine-absorbing properties of the cells of the diffuse endocrine system in the cortical lobular substance, but promotes serotonin accumulation in the amine-producing cells at the border of the thymus cortical and medullary lobules. Regardless of the photoperiod, exogenous melatonin increases the content of serotonin in the cells of the thymic diffuse endocrine system, which is more pronounced in continuous light conditions. Conclusions. Our studies have shown that changes in the photoperiod stimulate the serotoninergic system of the thymus, and exogenous melatonin smooths out these effects.





Fig. 1. Serotonin-positive cells (arrows) at the border of the cortical and medullary substance of the thymus lobes in animals kept for 4 weeks in the darkness (A), kept under continuous illumination (C) and treated with melatonin in the absence of light (B) and under continuous illumination (D). Immunohistochemical reaction to serotonin using monoclonal antibodies (clone 5HT-H209, DAKO, Denmark). Microscope objective 40, ocular lens 10.; Fig. 2. Changes in the amount and optical density of serotonin in the medullary (A, B) and cortical (B, D) substance of the thymus lobules in Wistar rats treated with melatonin under different light conditions. In fig. A, B on the ordinate axis is the number of cells, on the abscissa axis – the number of the experimental group. In fig. C, D on the ordinate axis is the optical density, on the abscissa axis – the number of the experimental group.