TRH Radio-Immunoassay

In repeated dose studies, hypothalamic tissue is readily available at autopsy of rats and can be used for the determination of hypothalamic hormone contents, it is important to take samples are rapidly and stop enzyme 

The TRH radio-immunoassay was developed as a double antibody assay, with modifications mainly depending on the antiserum used, and on the conditions of incubation. Addition of an enzyme inhibitor to the assay tubes is essential to avoid degradation of TRH in samples and of radioiodinated TRH. 

As with other radioimmunoassays, sample concentrations are calculated from a or standard curve of synthetic TRH. Using various doses of standard and test preparation, dose-response curve scan be established allowing calculation of sample concentrations, or potency ratios for tissue extracts tested at several concentrations. 

Modifications of this assay have been applied to the measurement in serum, in hypothalamic tissue homogenates and extracts, and in human urine. 

CRITICAL ASSESSMENT OF THE METHOD The method is of interest because the results can be correlated with measurements of pituitary TSH and prolactin secretion, and tissue content of these hormones. In a number of studies it has been shown, that changes in the secretion of thyroid hormone in the treated animals as well as administration of hormonally active compounds can change the hypothalamic TRH content in characteristic manner (Emerson and Utiger 1975, Schwinn et al. 1976, Simpkins et al. 1976). 

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