Roger Guillemin

Lability of Plasma TSH Levels in the Rat in Response to Nonspecific Exteroceptive Stimuli.

Summary Mild nonspecific exteroceptive stimuli such as handling, transferring from one room to another, and I.P. injections, lead to a rapid decrease of plasma TSH concentrations which become undetectable within 15 minutes following the beginning of the stressing procedure. There is evidence for a circadian rhythm of plasma TSH levels in opposite phases to those of the variations of plasma ACTH or corticosteroid variations. These observations are considered to be of importance to define resting levels of plasma TSH concentrations. For rats kept at 22°C ± 0.5, rapidly decapitated at 7:00 a.m., resting levels of circulating TSH are between 25–30 mU/100 ml plasma in this laboratory.

Competition Between Thyroxine and TRF at the Pituitary Level in the Release of TSH.

Summary When increasing amounts of thyroxine are administered to rats otherwise given an invariable dose of TRF, a dose of thyroxine is found to completely inhibit the TSH-releasing activity of that dose of TRF. Conversely, when increasing amounts of TRF are administered to animals pretreated with an invariable quantity of thyroxine known to inhibit the TSH releasing activity of several doses of TRF, a dose of TRF is eventually reached that will overcome the inhibitory effect of that amount of thyroxine. Neutron activation of a highly purified preparation of hypothalamic TRF failed to reveal presence of iodine in the TRF molecule.

ACTH release by in vitro pituitary; effect of pitressin and purified arginine-vasopressin.

Summary A modified tissue culture technic for rat pituitary was used for assaying the ACTH releasing activity of commercial Pitressin and purified vasopressin. Pitressin increased ACTH release whereas highly purified arginine-vasopressin had no effect. The ACTH hypophysotrope activity of commercial Pitressin is attributed to a contaminant of vasopressin of probable hypothalamic origin.

Filtration Chromatography on Substituted Sephadex in the Purification of the Hypothalamic Hormone TRF (TSH-Releasing Factor).∗:

Summary Purification of the TRF concentrate prepared by gel filtration of acetic acid extracts of hypothalamic tissues on Sephadex G-25 can be achieved following gel chromatography on carboxymethyl-Sephadex C-50 equilibrated in 0.001M pyridine acetate. The TRF activity is quantitatively eluted upon stepwise application of 0.09M pyridine acetate buffer. The method described can be used with small columns (4 × 15 cm) with charges ≤ 1 g TRF concentrate and also with large size preparative columns (15 × 33 cm) with charges up to 25 g of the TRF concentrate.