EFFECT OF HYPO- AND HYPERTHYROIDISM ON OVARIAN STRUCTURE AND FUNCTION IN RATS

Abstract

The aim of present study was to examine the effects of hypo- and hyperthyroidism induced during pre- and postnatal period of life on ovarian function and structure in female rats at 120 days of age. Three chemicals were used in this study. In prenatal group, treatment was given from conception to parturition. While in postnatal group, treatment was given from parturition to 25 days postpartum. Hypothyroidism was induced by administration of 0.1 % PTU in drinking water and by oral administration of 0.06mg malathion to mothers both for the pre- and postnatal treatment. Hyperthyroidism was induced by subcutaneous injection of 0.25~g thyroxine given to mothers in prenatal group, while in postnatal group 0.3~g/g BW (body weight) thyroxine was administered to the pups. Weekly body weight of the female pups were measured. In each group 10 female rats were sacrificed at 120 days of age. Postnatal PTU treated pups show delay in eye opening, teething, fur development and weaning (35-37 days) compared to control (28-30 days). Body weight of female rats in postnatal PTU, pre-and postnatal thyroxine treatment group was significantly decreased (P<0.001) while, prenatal PTU treatrnent group showed significant increase (P<0.0001) compared to control. There was significant (P<0.05) reduction in paired ovarian weight of postnatal PTU and thyroxine treatment group compared to control. Malathion treatment caused no effect on body and ovarian weight. Diameter of the ovaries was not affected by any treatment. Regarding the morphometery, only prenatal PTU treatment showed a significant (P<0.001) increase in diameter of graafian follicles. No significant difference was observed in morphometery of granulosa layer, primary and developing follicles of control and all treated groups. Number of primary, developing and graafian follicles of all the treated group were similar to that of control. The corpora lutea of postnatal PTU and thyroxine treated group contained a population of large numbers of luteal cells compared to control. All other treated groups have no profound effect on ovarian morphology, histology and morphometery. No difference was found ir serum estradiol concentration of control, pre- and postnatal PTU, malathion and thyroxine treated groups. In summary it is concluded from the present study that successful treatment of 0.1 {Yo PTU to immature fernale rats from 0-25 day postpartum effect the growth,. physical development ,caused a decrease in body weight and ovarian weight at day postpaltulTl also decrease the body and ovarian weight. T Ilis illdicate tile importarlce of tllyroid 110rmone ciuring the early postnatal period of life regardirlg the growth, physical development and ovarian weight. While pre- and postnatal . . malathion and pr Gnatsl PTU arld tllyroxine have no profound offect on ovarian Illor pllOlogy, histology and rnorphornetery All the treatment during the pre- and postr lat<ll [ler iod ()f life do !lot 811m tile concentration of estradiol at 120 day of age.