Effects of acute and chronic maternal deprivation on hypothalamo-pituitary adrenal axis in rat pups with hyperthyroidal mothers

ABSTRACT

Hyperthyroidism is a common endocrine problem encountered in human pregnancy. It is well known that hyperthyroidism induces an increase in the activity of hypothalamic-pituitary-adrenal [HPA] axis. Between the age of 4 and 14 days, the HPA axis of the rat displays a relative stress hyporesponsive period [SHRP]. There are no reports about development of the HPA axis in rat pups of hyperthyroid mothers. Therefore, this study was designed to investigate the effects of acute and chronic maternal deprivation on their pups HPA axis function of hyperthyroid mothers and the influence of treatment administration to hypothyroid mothers from conception to the end of experiment. 30 adult female rats were used after induction of pregnancy and hyperthyroidism. Maternal deprivation for 24 hours was done at two different ages during postnatal development at mid and outside the SHRP. Also, repeated maternal deprivation was done in another group. Now, pups groups are Control deprived, control non deprived, treated deprived, treated non deprived, nontreated deprived and nontreated nondeprived. The plasma thyroxin [T4] levels of treated deprived groups were significantly lower than non treated groups, while, plasma thyroid stimulating hormone [TSH] levels of treated groups were significantly higher than non treated deprived groups. There is no significant difference in plasma T4 between control and treated nondeprived group. There is no significant difference in plasma corticosterone and adrenocorticotropin hormone [ACTH] in treated deprived in comparison to treated nondeprived at postnatal day 9 and with repeated maternal deprivation. With repeated deprivation plasma corticosterone levels were not different in nontreated deprived group in comparison with the nontreated nondeprived group. Maternal deprivation in rats with hyperthyroidal mother depended on the age of pups at which procedure is applied