Maternal photoperiodic exposures alter the neonatal growth, pineal functions and sexual development of the Indian palm squirrel F. pennanti

Abstract

The phenomenon of maternal transfer of photic information to their young ones is still an enigma. Existing reports in some rodents of temperate zone suggest that photoperiodic condition experienced by mother during their gestation period influences the pineal physiology of fetus, but nothing has been reported about the growth and sexual development of pups. Present experiment for the first time explains the effect of gestational photoperiod on the growth and sexual development of pups from a seasonally breeding tropical rodent F. pennanti. The results suggest that, constant light (LL; 24L: OD) and long day length (LDL; 14L: 10D) experiencing mother conveyed the photic information to young ones to inhibit the pineal function, while short day length (SDL; 10L: 14D) stimulated the pineal function in pups. Altered pineal functions of pups ultimately interfered with their growth and sexual maturation. Most interestingly, the pups delivered by DD experiencing mothers and then reared under same condition, at the age of 40 days attained a level of growth and sexual maturity equivalent to the growth and sexual maturation of 60 days old pups under natural day length (NDL) condition. Therefore, we may suggest that the photic information perceived by the mother alter her normal melatonin level, hence, passing through placenta melatonin influences the growth and sexual maturation of the young ones.

Human placental trophoblasts synthesize melatonin and express its receptors

“…Melatonin has a wide variety of functions [12, 23]. It is known to play key roles in the endocrine control of reproductive physiology [29–31] and to be essential for growth and sexual maturation [32–34]. In humans, melatonin increases in concentration in maternal blood during pregnancy, reaching a maximum at term [35].…”

Environmental temperature during gestation and body mass index in adolescence: new etiologic clues?

“…28 It has been suggested that the photic experience of the mother during pregnancy alters the normal fetal melatonin level (via the placenta), influencing postnatal growth. 29 In support of this hypothesis, there is a significant decrease in plasma melatonin in obesity compared with anorexia nervosa. 30 There is a decreased secretion of melatonin at night in subjects suffering from Night Eating Syndrome, and an effect of this peptide on the hypothalamic -pituitary -adrenal axis may lead to an increased appetite (and thus a weight increase).…”

Implications of being born late in the active season for growth, fattening, torpor use, winter survival and fecundity

“…Similar to findings of Gotthard (2000) and Nylin et al (1996 ) that butterfly larvae ( Lasiommata maera and Pararge aegeria ) grew significantly faster when maintained under a late-season photoperiod, one might assume that day-length also acts as a crucial environmental cue for dormice to regulate their rate of growth. This might be even true for embryonic and early postnatal development, when offspring itself had no access to daylight, since mothers can transfer photoperiodic information to offspring through the placenta and/or milk via the hormone melatonin ( Bishnupuri and Haldar, 1999 ; Davis, 1997 ; Gündüz and Stetson, 2003 ). Thus, melatonin can be the foetus' window to periodicity of the outside world as described by Davis (1997) and may prompt LB dormice to accelerate their development.…”