Developmental Changes in Fetal Adrenal Hypertrophy following Maternal Bilateral and Fetal Unilateral Adrenalectomy at Different Stages of Gestation in the Rat

Abstract

Maternal adrenalectomy on days 14 and 15 of gestation did not alter the fetal adrenal weight 2 days later. The same operation on day 16 caused a significant increase in the adrenal weight with a hypertrophy of the cortical cells. Nevertheless, the operation on days 17 and 18 induced no change in the fetal adrenals. Subsequently on days 19 and 20, the operation resulted in a significant hypertrophy of the fetal adrenals. Fetal unilateral adrenalectomy on day 18 caused, 2 days later, significant hypertrophy of the contralateral adrenal, in contrast with no significant change after maternal adrenalectomy. This is perhaps due to the difference in the amount of fetal plasma corticoids, as evidenced by the previous reports of high concentrations of fetal plasma corticosterone on days 19 and 20. The overall results suggest that the fetal pituitary-adrenal feedback mechanism begins to appear between days 16 and 18 of gestation.

Compensatory Adrenal Hypertrophy following Unilateral Adrenalectomy of Fetuses of Rats Given Alcohol throughout Gestation

“…Histological sections also dem onstrate adrenal hypertrophy in adrenalecto mized fetuses, regardless of dietary treat-ment. Yamamoto et al [12] reported that adrenals of unilaterally adrenalectomized fe tuses showed a widening of the sinusoids and a reduction in the number of adrenocortical cells per microscope field, which is similar to the findings here. Thus, alcohol exposure does not prevent compensatory adrenal hy pertrophy in unilaterally adrenalectomized fetuses.…”

“…At the same time, the ratio of adrenal weight to body weight was significantly greater in the alcohol-fed fe tuses. Yamamoto et al [ 12] reported that the ratio of adrenal weight to body weight on day 22 of gestation was about 26.1 ±0.8 mg/ 100 g for unoperated controls and 33.3 ± 1.8mg/100g for adrenalectomized fetuses. These values are similar to those in the present study for water-fed and pair-fed lit ters.…”

“…Develop mental retardation occurs with respect to skeletal maturation, external morphologic indicators, palate formation, and, in rats, the maturation of the fetal thyroid gland [6][7][8], The mechanism by which alcohol retards growth and development is not clear, but several possibilities have been considered, including reduced placental blood flow and reduced nutrient transport to the fetus [9]. It has been proposed that the alcohol-exposed fetus may represent a 'developmentally younger' stage, compared to chronological age, and that this may account for the poten tiation by alcohol of the age-specific terato genic activities of vitamin A and methylmercury [ 10], It is well recognized that fetal unilateral adrenalectomy results in a compensatory hy pertrophy of the remaining adrenal gland, accompanied by alterations in adrenal his tology [11,12]. This compensatory response comes under control of the fetal pituitary prior to day 16 of gestation and under hypo thalamic control on about day 18 or 19 (vag inal plug = day 1) [13], Thus it represents a sensitive indicator of endocrine regulatory development and may be a useful system in which to examine fetal growth response to agents consumed by the mother.…”

Influence of Adrenalectomy on the Development of the Neonatal Thymus in the Rat

“…It is also well known that the hypothalamo-pituitary-adrenal axis operates well dur ing the late period of fetal life [12,19,24,31]. Maternal administration of ACTH and corticoids causes regression of the fetal thy mus [3,10].…”

The Sensitivity of the Fetal Rat Adrenal Gland to Adrenocorticotropic Hormone in vivo and in vitro

“…In our previous studies on the effects of maternal adrenalectomy and/or metopirone injection at different stages of gestation in the rat, the fetal pituitary-adrenal gland negative feedback mechanism was assessed as begin ning to operate between days 15 and 17 of gestation [14,15]. Although a certain amount of corticosterone can be detected in the plasma as well as in the adrenal gland of the fetal rat 17.5 days postcoitum [1][2][3][4], it is not clear when the fetal adrenal gland begins to respond to ACTH.…”