TSH Release from Anterior Pituitary Cells

Male Sprague-Dawley rats weighing 150-200 g serve as donors. After removal each pituitary is cut in half, transferred to a 15 ml beaker containing 1.5 ml Krebs-Ringer bicarbonate medium with 200 mg% glucose and incubated for three 60-min periods. The media used in the first 2 incubations are discarded. At the beginning of the third incubation period, various amounts of test preparation or TRH standard are added to individual beakers. At the end of the third incubation period the media from both control and experimental beakers are carefully aspirate, and the remaining pituitary tissue may be stored frozen for later determination of hormone contents. The incubation media are assayed by RIA for content of TSH, and other pituitary hormones of interest. 

Dose-response curves are established for test preparation and standard allowing calculation of potency ratios with confidence limits. 

For the assay of TRH analogues, cultures of enzymatically dispersed anterior pituitary cells from rats can be used instead of pituitary halves (Vale et al. 1972). 

Barros etal. (1986) studied the effect of TRH on cultured GH3 rat anterior pituitary cells using the wholecell voltage clamp technique. 

The method of testing in vitro on dispersed pituitary cells is essentially a static method for the comparison of hormones and hormone analogs. It has also been applied to the testing and pituitary tissue ex vivo, from animals that have undergone a period of treatment with compounds that are known to modify the pituitary response, e.g. synthetic corticoids. 

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