Enhanced triiodothyronine production in crested newts bearing permanent lesions to the anterior preoptic area.

In the crested newt, permanent lesions to the anterior preoptic area brought about an enhancement of triiodothyronine (T3) production. This was not mediated by prolactin, since the effect was demonstrable also in ergocryptine (CB 154)-treated animals. The observed rise in circulating T3 levels in the ergocryptine-treated surgical animals confirms that lesions to the anterior preoptic area stimulate pituitary thyrotrophic activity, resulting in the activation of the thyroid gland.

Effects of permanent deafferentation of the anterior preoptic area on serum aldosterone levels in the crested newt (Triturus cristatus carnifex Laur.).

By cutting off the fiber systems running along the medial forebrain bundle of the urodele amphibian Triturus cristatus, a wide deafferentation of the preoptic area was evoked. This operation elicited a decrease in aldosterone serum level, probably through a reduction of ACTH secretion. At present we are not able to ascertain whether such reduction was prompted by changes in the hypothalamic production of the neurohypophysial hormones or the corticotropin-releasing factor (CRF).

The effects of thyroidectomy on androgen and prolactin receptors in the dorsal skin and caudal fin of Triturus cristatus carnifex.

The interactions between thyroid hormones and receptors for steroid hormones and prolactin in dorsal skin and caudal fin of Triturus cristatus carnifex were studied during the annual cycle. Thyroidectomy induces an increase of prolactin binding in the dorsal skin and caudal fin in the animals captured in March. In these thyrodectomized animals the androgen receptors became undetectable. Results indicate that in Triturus cristatus carnifex the thyroid induces an increase of androgen receptors and a decrease, that is removed by thyroidectomy, of prolactin receptors.