title: Thyrotropin Releasing Hormone (TRH) in goldfish (Carassius auratus): role in the regulation of feeding and locomotor behaviors and interactions with the orexin system and cocaine- and amphetamine regulated transcript (CART).
abstract: TRH is a peptide produced by the hypothalamus which major function in mammals is the regulation of TSH secretion by the pituitary. In fish, TRH does not appear to affect TSH secretion, suggesting that it might regulate other functions. In this study, we assessed the effects of central (intracerebroventricular, icv) injections of TRH on feeding and locomotor behavior in goldfish. TRH at 10 and 100 ng/g, but not 1 ng/g, significantly increased feeding and locomotor behaviors, as indicated by an increase in food intake and in the number of total feeding acts as compared to saline-injected fish. In order to assess possible interactions between TRH and other appetite regulators, we examined the effects of icv injections of TRH on the hypothalamic expression of orexin, orexin receptor and CART. The mRNA expression levels of all three peptides were significantly increased in fish injected with TRH at 100 ng/g as compared to saline-injected fish. Fasting increased TRH, orexin, and orexin receptor hypothalamic mRNA levels and decreased CART hypothalamic mRNA levels. Our results suggest that TRH is involved in the regulation of feeding/locomotor activity in goldfish and that this action is associated with a stimulation of both the orexin and CART systems.
authors.affiliation: Department of Biology, Memorial University of Newfoundland, St John's, NL A1B3X9 Canada.
authors.forename: Meagan
authors.initials: M
authors.lastname: Abbott
authors.forename: Hélène
authors.initials: H
authors.lastname: Volkoff
mesh_terms: D000818:Animals; D001069:Appetite Regulation / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D005215:Fasting / Q000378:metabolism / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006054:Goldfish / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007276:Injections, Intraventricular; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008124:Locomotion / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics* / Q000378:metabolism; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology / Q000502:physiology*; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D013973:Thyrotropin-Releasing Hormone