Journal of Endocrinology and Reproduction

Rajesh Yadav ¹, Chandana Haldar ¹

Affiliations
1 Pineal Research Laboratory, Department of Zoology, Banaras Hindu University, Varanasi-221 005, IN

Abstract

Very little information is available to delineate the role of melatonin during the complex process of gestation in seasonally breeding mammals. The present study was aimed at understanding the physiology of gestation and fetal growth in relation to maternal hormonal levels, including melatonin, of a tropical seasonal breeder, Funambulus pennanti. Through assessment of the vaginal smear during breeding season (March) we selected the early pregnant females (∼5 days) from nature and provided them adequate facility in laboratory as in nature. The total length of gestation period i.e., ∼45 days, comparatively a long gestation period for a diurnal rodent, was recorded. The litter size was small (3-4), with the maximum number of pregnancies during March to May (in August to September, very less) depending upon the availability of food. The intrauterine growth of the fetus is divisible into three phases, i) implantation and cell division, ii) organ formation, and iii) growth and completion of intrauterine development. A method for the quantitative analysis of fetal growth was devised. A correlation with the levels of maternal hormones suggests that a direct relationship of progesterone and melatonin exists during pregnancy, which declined immediately after parturition. The high melatonin level during gestation, having an almost inverse relationship with estradiol level, suggests that melatonin might play a role in maintenance of pregnancy. Variations, if any, in the melatonin receptor expression in the uterus throughout the gestation period may throw some light on the role of melatonin in maintenance of pregnancy.

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Sweta Arora ¹, Rajesh Yadav ², Chandana Haldar ¹

Affiliations
1 Pineal Research Lab, Department of Zoology, Banaras Hindu University, Varanasi, Varanasi - 221005, Uttar Pradesh, IN
2 Dr. Bhim Rao Ambedkar Government Degree College, Dhaneva Dhanei, Maharajganj, Uttar Pradesh, IN

Abstract

Pregnancy is associated with profound immunological changes that are characterized by a strong activation of certain components of the innate immune defense and a down-regulation of adaptive immune functions. This shift in balance of the immune system towards an innate dominance is thought to be important for the maintenance of pregnancy. Based on our observation in the short nosed fruit bat Cynopterus sphinx, a seasonal breeder, we show for the first time that melatonin injection to the pregnant females significantly increases lymphocyte proliferation of spleen and consequently the circulating level of lymphocytes and percent stimulation ratio of splenocytes, thereby improving immune status during pregnancy. We have reported earlier that during pregnancy melatonin level increases significantly which in turn might improve the maternal immunity. Towards establishing this inference we used a physiological dose of p-chlorophenylalanine (p-CPA), an indirect antagonist of melatonin, which reduced circulatory melatonin level and thereby reduced the immune status. It is conceived that specific immune adaptation is conveyed to the fetus through placental transfer of melatonin thereby controlling fetal immunity as well. This could be an adaptation during pregnancy to protect the mother from various external threats.

Keywords

Cynopterus Sphinx, Immunity, Melatonin, Pregnancy.

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