Postnatal Maturation Patterns of Serum Corticosterone and Growth Hormone in Rats: Effect of Chronic Thyroxine Administration

Re, Poland; Me, Weichsel; Rt, Rubin

doi:10.1055/s-0028-1092713

Cited by 33 publications

(12 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, neonatal Tj administration re sults in an early increase in basal corticosterone titers and CBG levels [6,10,22] as well as in the early maturation of the adrenocortical response to stress [29]. In contrast, PTU administration during this period delays the maturation of the adrenocortical stress response and suppresses CRF-like activity in the hypothalamus [23,24].…”

Section: Discussionmentioning

confidence: 98%

Thyroid Hormones Influence the Development of Hippocampal Glucocorticoid Receptors in the Rat: A Mechanism for the Effects of Postnatal Handling on the Development of the Adrenocortical Stress Response

1987

View full text Add to dashboard Cite

The role of thyroid hormones on the development of intracellular glucocorticoid receptor concentrations was examined in the hippocampus, hypothalamus, and pituitary of the rat. Adult animals, administered triiodothyronine (T3; 1.0 µg/g body weight) on days 1, 2, and 4 of life or thyroxine (T₄; 2.5 µg/g body weight) on days 1 and 2 of life, had significantly elevated glucocorticoid receptor concentrations in the hippocampus, but not in hypothalamus or pituitary. Adult animals treated with propylthiouracil (PTU; 0.2% in the mother’s food), a thyroid hormone synthesis inhibitor, for the first 2 weeks of life showed decreased glucocorticoid receptor concentrations in hippocampus, but not in hypothalamus or pituitary. We then examined whether thyroid hormones might mediate the effects of early stimulation on the development of hippocampal glucocorticoid receptor concentrations. Animals that were handled for 15 min daily (Ha) for the first 2 weeks of life showed increased hippocampal glucocorticoid receptor concentrations as adults compared to nonhandled (NHa) controls. PTU administration blocked the effects of handling, such that Ha/PTU animals showed hippocampal glucocorticoid receptor concentrations that were indistinguishable from those of NHa animals. In contrast, corticosterone administration over the first 2 weeks of life had no effect on adult hippocampal glucocorticoid receptor concentrations. These data suggest that thyroid hormones mediate, in part at least, the development of glucocorticoid receptor concentrations in the hippocampus and that this effect occurs independently of their effects on corticosterone titers.

show abstract

Section: Discussionmentioning

confidence: 98%

Thyroid Hormones Influence the Development of Hippocampal Glucocorticoid Receptors in the Rat: A Mechanism for the Effects of Postnatal Handling on the Development of the Adrenocortical Stress Response

1987

View full text Add to dashboard Cite

show abstract

“…Plasma ACTH levels are increased in neo-T4 rats with respect to controls at 12 days of life (table III) which could be an effect of the administration of thyroxine until the 8th day of life, considering that the chronic adminis tration of this hormone induces an increase in plasma corticosterone [26], In cortisoltreated animals, ACTH is decreased since the 8th day of life. This explains why authors [10,11,29] found a decrease in response to ether at 23 days of life in control-treated rats be cause they compared the response to normal rats treated with ether and not to the basal levels in the former groups.…”

Section: Discussionmentioning

confidence: 99%

Influence of Hormones and Undernutrition on Brain Development in Newborn Rats

Pascual-Leone¹,

Escrivá²,

Álvarez³

et al. 1985

Neonatology

View full text Add to dashboard Cite

High L-thyroxine (T₄) and cortisol doses given to rats during the first 8 days of life and on the first day only respectively, produce decrease of body and brain weight and perturbances to brain energy substrates, i.e. glucose and ketone bodies. The same alterations are found in the undernourished rats from the prenatal period. The pituitary GH and TSH is decreased in the T₄- and cortisol-injected animals. The plasma ACTH is decreased in the treated cortisol animals at 8, 12 and 22 days of life. The pituitary TSH content is reduced with respect to controls in the undernourished animals from 14 to 70 days of life. From the exposed experiments we suggest an alteration in the hypothalamic-pituitary complex in T₄- and cortisol-treated rats, and describe the similarities between the three experimental models.

show abstract

“…This impairment could be related to the major disturbance of carbohydrate metabolism of neo-T4 rats in the neonatal period, with low liver glycogen, blood glucose and insulin levels, which implies a lack of energy substrates for the neonatal brain (Escrivá & Pascual-Leone 1981;Dickerman et al 1969). On the other hand these alterations in pituitary GH content could be a consequence of treatment with thyroid hormones, since chronic neonatal hyper¬ thyroidism, though produced by much smaller doses of T4, has been shown to alter the develop¬ mental pattern of serum GH (Poland et al 1979).…”

Section: Discussionmentioning

confidence: 98%

Effects of l-thyroxine treatment on pituitary GH content of adult rats with neonatal thyrotoxicosis

Pascual-Leone

Besa

Hervás

et al. 1983

Acta Endocrinologica

View full text Add to dashboard Cite

Rats receiving large doses of thyroxine (30 \ g=m\ g/ 5 doses) during their first days of life develop an apparently permanent alteration of the hypothalamus-pituitary-thyroid complex. This neonatal thyrotoxicosis has been called neo-T4 syndrome. A state of permanent but not very severe hypothyroidism seems to be induced, accompanied by a decrease in pituitary GH content at least until day 22. In this work, growth hormone content has been measured by a specific radioimmunoassay in the anterior pituitary of 45 and 78 day old neo-T4 and control (saline-injected) rats. GH content of the adult neo-T4 treated animals was significantly lower than that of the adult controls. Administration of different doses of T4 (1.7 \g=m\g/100g body weight/3 doses or 2.5 \g=m\g/100g body weight/8 doses, to 70 day old rats, and 5 \g=m\g/100g body weight/3 doses to 42 day old rats) to adult neo-T4 rats did not alter these decreased pituitary GH levels.This differs from hypothyroid rats, in which T4 administration has been shown to increase pituitary GH content. A third approach was to thyroidectomize neo-T4 and control rats and administer 5 \g=m\g T4/100 g body weight, which produced the same increase in pituitary GH in both groups of animals. These results seem to indicate that changes in pituitary GH content of neo-T4 rats are not due to hypothyroidism. Thus, it would appear that treatment with large T4 doses during the early perinatal period not only deranges the hypothalamic-pituitary\x=req-\ thyroid axis but other pituitary functions as well.It has repeatedly been observed that large doses of thyroxine produce an alteration of the hypothalaRequests of reprints:

show abstract

Postnatal Maturation Patterns of Serum Corticosterone and Growth Hormone in Rats: Effect of Chronic Thyroxine Administration

Cited by 33 publications

References 15 publications

Thyroid Hormones Influence the Development of Hippocampal Glucocorticoid Receptors in the Rat: A Mechanism for the Effects of Postnatal Handling on the Development of the Adrenocortical Stress Response

Thyroid Hormones Influence the Development of Hippocampal Glucocorticoid Receptors in the Rat: A Mechanism for the Effects of Postnatal Handling on the Development of the Adrenocortical Stress Response

Influence of Hormones and Undernutrition on Brain Development in Newborn Rats

Effects of l-thyroxine treatment on pituitary GH content of adult rats with neonatal thyrotoxicosis

Contact Info

Product

Resources

About