ABSTRACT
Exposure of intact and ovariectomized rats to high ambient temperature (34.4 degrees C, 60-65% relative humidity) resulted in reduction of their body weight, increased water consumption. The feed consumed which was lowered by 25% initially, did not alter later. Intact rats were also subjected to a still higher ambient temperature of 36.6 degrees C and 70 to 75% RH and the effects were observed. When compared with 'controls' no significant changes in the weights of ovaries or pituitary gland were seen due to heat stress in intact rats. But, the latter weighed heavier in ovariectomized rats. Adrenal glands were found enlarged and weighed more both in intact and ovariectomized rats. The average foetal weight due to high ambient temperature in intact rats was lower, but in ovariectomized rats it weighed more. Similarly, the average weight of the placenta was lower in intact rats but higher in ovariectomized rats due to thermal stress.
Subject(s)
Adrenal Glands/pathology , Animals , Castration , Female , Fetus/pathology , Hot Temperature , Organ Size , Ovary/pathology , Pituitary Gland/pathology , Placenta/pathology , Pregnancy , Pregnancy Complications/pathology , Rats , Stress, Physiological/pathologyABSTRACT
High ambient temperature (34.4 C degrees and 60-65% relative humidity (RH) did not affect foetal survival when bred female rats were exposed between day-8 and -18 (Day-0=day of breeding). Heat-stress at this intensity given on day-0 was critical for embryonic and/or foetal survival rate and more so, if the ambient temperature was increased to 36.6 C degrees and 70-75% RH than on day-1. Postimplantation foetal survival was reduced due to heat-stress given only during early gestation period.
Subject(s)
Animals , Embryonic Development , Female , Fetal Death/epidemiology , Hot Temperature/adverse effects , Humidity , Pregnancy , Pregnancy, Animal , Rats , Time FactorsABSTRACT
High ambient temperature (34.4 C degrees and 60-65% relative humidity (RH failed to maintain optimum embryonic and/or foetal survival rate in ovariectomized pregnant rats given exogenous progesterone and oestrone injections. A still higher ambient environment (36.6 C degrees and 70-75% RH) did not affect the decidual cell response (DCR) in psuedo-pregnant rats. Heat stress did not result either in insufficiency or lack of progesterone and hence the latter two are not factors for the heat stress causing embryonic and/or foetal loss. The possibility of the failure of oestrone being converted to oestradiol or an intrinsic interference of RNA synthesis to be the factors responsible for embryonic and/or foetal loss caused by heat stress has been examined.