Age-dependent changes in the inactivation of thyrotrophin-releasing hormone by different areas of rat brain

Age-dependent changes in the inactivation of thyrotrophin-releasing hormone (TRH) were investigated in two subcellular fractions prepared from hypothalamus, thalamus, cortex and cerebellum of male rats. It was found that, in both supernatant and particulate fractions from the four brain areas, enzyme activity increased to a peak at 10-25 days of age and then decreased gradually until adult levels were reached. The changes in TRH degradation observed may be related to alterations in hypothalamic TRH content with age and to maturation of the tripeptide's putative neurotransmitter/neuromodulator function.