title: Distribution of hypophysiotropic thyrotropin-releasing hormone (TRH)-synthesizing neurons in the hypothalamic paraventricular nucleus of the mouse.
abstract: Hypophysiotropic thyrotropin-releasing hormone (TRH) neurons, the central regulators of the hypothalamic-pituitary-thyroid axis, are located in the hypothalamic paraventricular nucleus (PVN) in a partly overlapping distribution with non-hypophysiotropic TRH neurons. The distribution of hypophysiotropic TRH neurons in the rat PVN is well understood, but the localization of these neurons is unknown in mice. To determine the distribution and phenotype of hypophysiotropic TRH neurons in mice, double- and triple-labeling experiments were performed on sections of intact mice, and mice treated intravenously and intraperitoneally with the retrograde tracer Fluoro-Gold. TRH neurons were located in all parts of the PVN except the periventricular zone. Hypophysiotropic TRH neurons were observed only at the mid-level of the PVN, primarily in the compact part. In this part of the PVN, TRH neurons were intermingled with oxytocin and vasopressin neurons, but based on their size, the TRH neurons were parvocellular and did not contain magnocellular neuropeptides. Co-localization of TRH and cocaine- and amphetamine-regulated transcript (CART) were observed only in areas where hypophysiotropic TRH neurons were located. In accordance with the morphological observations, hypothyroidism increased TRH mRNA content of neurons only at the mid-level of the PVN. These data demonstrate that the distribution of hypophysiotropic TRH neurons in mice is vastly different from the pattern in rats, with a dominant occurrence of these neurosecretory cells in the compact part and adjacent regions at the mid-level of the PVN. Furthermore, our data demonstrate that the organization of the PVN is markedly different in mice and rats.
authors.affiliation: Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary 1083.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kádár
authors.forename: Edith
authors.initials: E
authors.lastname: Sánchez
authors.forename: Gábor
authors.initials: G
authors.lastname: Wittmann
authors.forename: Praful S
authors.initials: PS
authors.lastname: Singru
authors.forename: Tamás
authors.initials: T
authors.lastname: Füzesi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Marsili
authors.forename: P Reed
authors.initials: PR
authors.lastname: Larsen
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Liposits
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Lechan
authors.forename: Csaba
authors.initials: C
authors.lastname: Fekete
mesh_terms: D000818:Animals; D007037:Hypothyroidism; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010121:Oxytocin / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*; D014667:Vasopressins / Q000378:metabolism
chemical_list: D014667:Vasopressins; D010121:Oxytocin; D013973:Thyrotropin-Releasing Hormone