Characterization of immunoreactive thyrotropin releasing hormone in human fetal cerebellum

High concentrations (411 +/- 30 pg/mg protein; mean +/- S.E., n = 12) of immunoreactive TRH (TRHi) were detected in extracts of human fetal cerebellum (13-26 weeks gestation). The TRHi in the cerebellar extracts, when subjected to gel filtration and high performance liquid chromatography (HPLC), co-migrated with synthetic TRH. In each instance, no TRHi was detected which did not share identical chromatographic mobilities with synthetic TRH. Like synthetic TRH, the TRHi in extracts of fetal cerebellum and hypothalamus was insoluble in diethyl ether and was efficiently degraded when incubated at 37 degrees C with adult rat serum. No significant degradation of TRHi occurred when the incubation was conducted at 0 degrees C or when the extracts were incubated with rat serum that had been preheated at 60 degrees C for 20 min. Neither synthetic TRH nor TRHi in extracts of fetal cerebellum of hypothalamus was degraded when incubated with human umbilical cord serum at 37 degrees C or 0 degrees C. The results of this study are supportive of the view that the TRHi in extracts of human fetal cerebellum is identical to TRH.