Roger Burgus

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.

[33] Alcohol-chloroform extraction of hypothalamic hypophysiotropic peptides

Publisher Summary The methods described for the extraction of hypothalamic factors from tissues have utilized saline or dilute aqueous acids; however, organic solvents such as glacial acetic acid, ethanol, methanol, butanol, and phenol have been used in extraction of tissues or partitioning of partially purified extracts. Surveys of extraction solvents for thyrotropin releasing factor (TRF) and luteinizing hormone releasing factor (LRF) showed that both of these peptides, as judged by biologic activities, were extracted from crude preparations by aqueous methanol. Less TRF or LRF biologic activity was extracted by absolute methanol and little, if any, by petroleum ether, diethyl ether, chloroform, ethyl acetate, or pyridine. The method described in this chapter employs the extraction of lyophilized powder of hypothalamic tissue by a 90% aqueous ethanol-chloroform mixture. This procedure has been used successfully in programs of isolation and determination of the structures of ovine TRF and LRF2. The yields of hormones extracted by this method are comparable to those obtained using two N acetic acid or glacial acetic acid to extract TRF and LRF.