Degradation of TRF immunoreactivity in rat hypothalamus, extrahypothalamic brain and pancreas.

The endogenous TRF as measured in radioimmunoassays of chromatographically purified extracts of excised hypothalami, extrahypothalamic brains and pancreas was shown to be stable in intact organs and homogenates. However, synthetic TRF added to tissue homogenates was degraded. Sonication of the homogenates liberated endogenous TRF for degradation. Chromatographically purified tissue extracts of hypothalamus, extrahypothalamic brain and pancreas were degraded similarly by rat serum. These results suggest that the major portion of endogenous TRF occurs in a protected form in tissues and hence the physiologically effective amount of TRF must be very low when compared to its total content in tissues.