Characterization of an avian histidine decarboxylase and localization of histaminergic neurons in the chicken brain

• Published in: Neuroscience letters 2014-08, Vol.578, p.106-110
• Main Authors: Bessho, Yuki, Iwakoshi-Ukena, Eiko, Tachibana, Tetsuya, Maejima, Sho, Taniuchi, Shusuke, Masuda, Keiko, Shikano, Kenshiro, Kondo, Kunihiro, Furumitsu, Megumi, Ukena, Kazuyoshi
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Brain; Brain - enzymology; Chicken; Chickens; CHO Cells; Cricetulus; Feeding Behavior - drug effects; Food intake; Histamine; Histamine - biosynthesis; Histamine - pharmacology; Histidine decarboxylase; Histidine Decarboxylase - metabolism; Hypothalamus; Male; Mammillary Bodies - enzymology; Molecular Sequence Data; Neurons - enzymology; RNA, Messenger - metabolism
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2014.06.048

•Histidine decarboxylase (HDC) cDNA was cloned from chicken hypothalamic mRNA.•The chicken HDC protein possessed the ability to convert histidine to histamine.•HDC mRNA was localized in the medial mammillary nucleus of the hypothalamus.•Intracerebroventricular injection of histamine decreased food intake in the chicks.•This is the first report characterizing the histaminergic system in the avian brain. In mammals, it is established that histamine is a neurotransmitter and/or neuromodulator in the central nervous system. It is produced by the enzyme histidine decarboxylase (HDC) in the tuberomammillary nucleus of the posterior hypothalamus. However, HDC as well as histaminergic neurons have not yet been characterized in the avian brain. We have cloned the cDNA for HDC from the chicken hypothalamus and demonstrated that the chicken HDC sequence is highly homologous to the mammalian counterpart, and that the expressed protein shows high enzymatic activity. The expression of HDC mRNA at various sites in the brain was investigated using quantitative RT-PCR. The results showed that the HDC mRNA was highly expressed in the hypothalamic infundibulum. In situ hybridization analyses revealed that the cells containing HDC mRNA were localized in the medial mammillary nucleus of the hypothalamic infundibulum. Intracerebroventricular injection of histamine in chicks resulted in inhibition of feeding behavior. This is the first report of the characterization of histaminergic neurons in the avian brain, and our findings indicate that neuronal histamine exerts anorexigenic effects in chicks.