Human Semen Contains Thyrotropin Releasing Hormone (TRH), a TRH‐homologous Peptide, and TRH‐binding Substances

Abstract

High levels of thyrotropin releasing hormone (TRH) and TRH-homologous peptide, with the general structure pGlu=X-Pro-NH2 where X is either Histidine (His) or a neutral amino acid residue, have been identified in rat and human prostate (Pekary et al, 1980, 1981a, 1982c). Because of the secretory nature of prostatic tissue, it was considered likely that these peptides would be measurable in human semen. The mean (+/- SD) TRH immunoreactivity (TRH IR) in semen from 26 normal donors, aged 26 and 41 years, was found to be 12.2 +/- 5.2 ng/ml. TRH and TRH-homologous peptide, were undetectable in unconcentrated human serum. TRH IR levels in semen from azoospermic donors were in the normal range. The level of TRH IR in semen from vasectomized donors was significantly less (P less 0.01) than in semen from normal subjects. Evidence for at least two TRH-binding substances, which coextract and bind to added synthetic TRH, was obtained by exclusion and cation exchange chromatography. Purification of extracts of human semen by TRH affinity chromatography or gradient, reversed phase high pressure liquid chromatography (HPLC) revealed two major TRH immunoreactive peptides, one corresponding to the TRH-homologous peptide previously reported in rat and human prostate and one cochromatographing with synthetic TRH.

High Levels of Thyrotropin-Releasing Hormone Precursor Peptide Immunoreactivity and Binding Substance Occur in Human Cerebrospinal Fluid

“…This observation is consistent with other studies which have found high concentrations of these peptides in rat hypothalamus [7,16,17], spinal cord [18], pancreas [ 19], prostate [8,11], anterior and posterior pituitary [17], semen [20,21] and frog skin [6], The levels of TRH-Gly-IR in CSF from MS and ALZ patients were significantly elevated compared to control CSF samples, which is consistent with earlier reports of elevation of TRH-1R in CSF from these patients [I], The lack of correlation of the TRH-and TRH-Gly-IR levels in CSF may have been due, in part, to the inadequate sensitivity of our TRH RIA in relation to the very low TRH-1R levels of CSF.…”

Is Ps4 (prepro-TRH [160-169]) More Than an Enhancer for Thyrotropin-Releasing Hormone?

“…The function of high levels of Ps4 receptor in the vas deferens, given the very low levels of endogenous Ps4 in this tissue, seemed puzzling until very high levels of Ps4 were detected in rat prostate and epididymis (Pekary, unpublished results), which are also the major sources of TRH in the male rat, dog, and human reproductive systems and semen (29)(30)(31)(32)(33)(34).…”

“…TRH, TRH-Gly, and cyclo(His-Pro), a metabolite of TRH, occur in high levels in fresh human semen (29,32,33), TRH-Gly can be converted to TRH by in vitro incubation with human semen (33) and TRH is a direct stimulator of cardiac contractility (35). We hypothesize that TRH facilitates vas deferens contractility during ejaculation and that this effect is enhanced by Ps4 in seminal components arising from the prostate and epididymis as seen in Figure 3 and (38).…”

Thyrotrophin-releasing hormone in human ejaculate

“…The present report describes the results of studies on the stability and Chromatographie separation of seminal plasma TRH. These studies were initiated 3 years ago, coinci¬ dent with the work of Pekary, Hershman & Friedman (1983), when there was still confusion about the form in which the hormone existed in these tissues and fluids.…”