Journal of Endocrinology and Reproduction

R. Yadav ¹, C. Haldar ¹, L. K. Pandey ²

Affiliations
1 Pineal research Lab., Department of Zoology, Banaras Hindu University, Varanasi – 221 005, IN
2 Department of Obstetrics and Gynecology, Institute of Medical Sciences, Banaras Hindu University, Varanasi – 221 005, IN

Abstract

There is lack of basic information about peripheral melatonin level and its relationship with gestational hormones i.e., estrogens and progesterone, in human females. The present study addressed this issue and aimed to find the relationship between the levels of melatonin and estrogen and progesterone during different weeks of gestation, during parturition and during post-partum. The data suggest that there is a definite ratio of melatonin with both the steroids hormons before and during gestation as well as post-partum. An inverse relationship between the levels of estrogen and melatonin was observed in non-pregnant and post-partum women, while a direct relationship was observed during gestation. These two different types of hormonal relationships might be essential for maintenance of pregnancy. The inverse relationship of melatonin with progesterone during parturition may serve as a signal for parturition.

Keywords

Melatonin, Estradiol, Progesterone, Gestation, Parturition, Post-Partum.

Full Text

     

R. Tripathi ¹, C. Haldar ¹, R. Yadav ¹

Affiliations
1 Department of Zoology, Banaras Hindu University, Varanasi-221005, IN

Abstract

Phosphorylation of thymidine, a key step in pyrimdine salvage pathway involved in DNA synthesis is catalyzed by Deoxythymidine kinase [Thymidine kinase (TK)-ATP: thymidine 5'-Phosphotransferase, EC: 2.7.1.21]. Several authors correlated changes in TK activity and ³H-Thymidine incorporation into DNA of various tissues or with cell divisions or under influence of EGF (Lewinski et al., 1997) and found that the relationship was a proportional one (Kahn et al, 1980; Zieve 1985).

Full Text

     

C. Haldar ¹, R. Yadav ¹

Affiliations
1 Pineal Research Lab, Department of Zoology, Banaras Hindu University, Varanasi - 221005, IN

Abstract

The pineal gland, the transducer of several environmental cues through its hormone, melatonin, is known to play a critical role in the reproduction of several seasonally breeding mammals. The role of pineal gland in the control of male reproduction is already established beyond doubt. The logical hypothesis that the pineal gland would be involved in the aspects of female reproduction, particularly gestation, embryonic development and fetal growth, has been tested in a few seasonally breeding mammals and this paper reviews the outcome as of now. Evidence for establishment of an inverse relationship before pregnancy followed by moderately high activity with a positive correlation during pregnancy and a sudden increase in pineal activity during parturition has been produced, which suggests that high melatonin level has something to do with parturition or early abortion. The pineal gland perhaps maintains the normal physiology during gestation and post-parturition periods. This is further reflected in the prolactin levels of fetal sheep which is modulated by the photoperiod experienced by the mother during gestation. Maternal photoperiodic exposures during gestation and lactation periods alter the neonatal growth and sexual maturation of the Indian palm squirrel via the maternal transfer of photoperiodic information through the pineal gland, as aspect known as "pineal programming". The primary source of melatonin for the fetus is the maternal pineal gland, which is transferred across the placenta during conception and, later after parturition, through the milk, which suggests that a maternally generated melatonin rhythm would be expressed in fetal cerebrospinal fluid as well as in the circulation. Further, maternal melatonin is necessary for normal somatic growth and postnatal development of reproductive organs of the offspring. Melatonin ultimately affects reproductive activity by modulating hypothalamic neuroendocrine circuits whose activity is necessary for gonadal function. The influence of melatonin on reproductive development begins during the prenatal period and extends into the postnatal life. Photoperiodic information, mediated via the pineal gland may be important for maintaining gestational physiology as well as postpartum recovery in female rodents. Further, melatonin has been shown to play adaptive role in the maintenance of delayed embryonic development in bats. Correlation between a developmental decline in melatonin levels and the timing of puberty in humans led to the speculation that melatonin regulates the timing of puberty in the human. These studies on the influence of melatonin on gestation indicate two major inferences viz., melatonin could be one of the major hormones establishing homeostasis during gestation since any disturbance in the level of melatonin causes abortion, and melatonin is one of the hormones of great adaptive significance for embryonic diapause.

Keywords

Embryonic Growth, Gestation, Melatonin, Photoperiod, Pineal Gland, Puberty.

Full Text