Concentration and Distribution of TRH and LRH in the Human Fetal Brain1

Abstract

TRH and LRH were measured in methanolic extracts of brain tissue from human fetuses as early as 4.5 weeks after conception. The greatest concentration of both releasing hormones was in the hypothalamus, (TRH = 51 ± 19 pg/mg wet wt; LRH = 21 ± 7 pg/mg wet wt; mean and SE). Significant levels of TRH were measured in the cerebellum (8 ± 2 pg/mg wet wt), whereas LRH was frequently below the limit of detection in extrahypothalamic sites. The cerebellum of an anencephalic infant included in the study contained one of the higher concentrations of TRH as compared to the other samples of cerebellar tissue. These findings are compatible with the view that TRH may be a peptidergic neurotransmitter.