title: Thyrotropin-releasing hormone (TRH), a signal peptide of the central nervous system.
abstract: 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 localized on the surface of neuronal cells which has been termed TRH-degrading ectoenzyme (TRH-DE) since it selectively inactivates TRH. Vice versa it also holds true that TRH is selectively inactivated only by TRH-DE and thus, this enzyme might be considered to be the terminator of TRH signals. In situ-hybridization histochemistry was used to study the TRHergic communication system by analyzing the gene expression of TRH-DE in relation to TRH and to the TRH receptors (TRH-R1 and TRH-R2). TRH mRNA is highly expressed in "thyrotropic" hypothalamic regions and in some selected brain areas. For TRH-R1 and TRH-R2, an almost exclusive mRNA distribution pattern was noticed in many brain regions. Interestingly, a widespread distribution of TRH-DE predominantly in neo- and allocortical regions was observed essentially overlapping the distribution patterns of TRH-R1 and TRH-R2. These data support the hypothesis that TRH-DE is important in the TRH-mediated modulation of sensory, locomotor and cognitive functions of the CNS and could be considered to be a marker to map TRHergic pathways.
authors.affiliation: Max-Planck Institute for Experimental Endocrinology, Hannover, Germany. Karl.Bauer@mpi_han.mpg.de
authors.forename: H
authors.initials: H
authors.lastname: Heuer
authors.forename: M K
authors.initials: MK
authors.lastname: Schäfer
authors.forename: K
authors.initials: K
authors.lastname: Bauer
mesh_terms: D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007031:Hypothalamus / Q000473:pathology*; D018377:Neurotransmitter Agents / Q000235:genetics*; D021382:Protein Sorting Signals / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D018025:Receptors, Thyrotropin-Releasing Hormone / Q000235:genetics; D009435:Synaptic Transmission / Q000235:genetics / Q000502:physiology; D013973:Thyrotropin-Releasing Hormone / Q000235:genetics*
chemical_list: D018377:Neurotransmitter Agents; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D018025:Receptors, Thyrotropin-Releasing Hormone; D013973:Thyrotropin-Releasing Hormone