It has been found previously that nicotine inhibits ovulation and fertili­zation both in vivo and in vitro in rats. Furthermore the onset of puberty was reported to be associated with changes in pulsatile gonadotrophm -releasing hormones secretion in the hypothalamus. The objective of this study was to test the hypothesis that nicotine perturbs the onset of puberty and to explain the mechanism of this effect. In addition, it has been reported previously that nicotine may alter uterine fallopian tube function which mediate gamete and conceptus transport, so this work was also aiming at evaluation of difference in response of isolated rat uterus to either serotonin or oxytocin in nicotine pretreated and untreated female rats.
Nicotine in a dose of 0.5mg/kg/d. was injected I.P. to female rats from the day 15 of postnatal life induced retardation of the onset of puberty as assessed in. terms of vaginal opening (64.3 + 3.2 VS43.5±2.1 day in sa­line treated control). In addition the animate which have been given nico­tine showed a significant decrease in serum levels of FSH, LH, oestrogen and progesterone beside increased serum level of prolactin as compared to saline treated control. The number of ova in the fallopian tubes released at first ovulation, weight of ovaries, uteri and whole body weight were significantly lower in comparison with nicotine untreated rats. Furthermore, postnatal life administration of nico­tine in a dose of 0.5mg/kg/d, I.P. from the day 15 of age until the day of first ovulation induced a significant.