This family consists of several thyrotropin-releasing hormone (TRH) proteins. Thyrotropin-Releasing Hormone (TRH; pyroGlu-His-Pro-NH2), originally isolated as a hypothalamic neuropeptide hormone, most likely acts also as a neuromodulator and/or neurotransmitter in the central nervous system (CNS). This interpretation is supported by the identification of a peptidase localised on the surface of neuronal cells which has been termed TRH-degrading ectoenzyme (TRH-DE) since it selectively inactivates TRH [1]. TRH has been used clinically for the treatment of spinocerebellar degeneration and disturbance of consciousness in humans [2].

1: Thyrotropin-releasing hormone (TRH), a signal peptide of the central nervous system. Heuer H, Schafer MK, Bauer K; Acta Med Austriaca 1999;26:119-122. PMID:10526628

2: Neuroprotective effect and brain receptor binding of taltirelin, a novel thyrotropin-releasing hormone (TRH) analogue, in transient forebrain ischemia of C57BL/6J mice. Urayama A, Yamada S, Kimura R, Zhang J, Watanabe Y; Life Sci 2002;72:601-607. PMID:12467901