ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2015, Vol. 46 ›› Issue (4): 576-582.doi: 10.11843/j.issn.0366-6964.2015.04.010

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Investigation into Synthesis and Secretion of Melatonin in Thyroid Gland in Sheep

OU Ke-peng1# ,LI You-jian1# ,GUO Ruo-ting1,WANG Ying1,GU Zhen-zhen1,LIU Yi1,LIU Xiao-jun2*   

  1. (1.College of Animal Science and Technology,Shihezi University,Shihezi 832003,China;2.College of Animal Science and Veterinary Medicine,Henan Agricultural University,Zhengzhou 450002,China)
  • Received:2014-10-28 Online:2015-04-23 Published:2015-04-23

Abstract:

 The objectives of present study were to investigate whether two key genes of enzymes for melatonin biosynthesis,arylalkylamine N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT),and melatonin receptor MT1 were expressed in thyroid gland in sheep,and whether melatonin could be independently synthesized and secreted in the gland.The expression of AANATHIOMT and MT1 was firstly detected by using RT-PCR,and was then confirmed by immunofluorescenct histochemical assay in tissues of thyroid gland of sheep.The specificity of cultured primary thyroid gland cells was characterised by immunofluorescenct cytochemical assay.The synthesis and secretion of melatonin in sheep thyroid gland cells were analysed using ELISA.The results showed that AANATHIOMT and MT1 mRNAs were expressed in sheep thyroid tissue.Immunofluorescence assays confirmed that HIOMT and MT1 protein were localized on follicular cells in thyroid gland.Meanwhile,ELISA assay demonstrated that the thyroid gland of sheep could synthesize and secret melatonin autonomously.The present study evidenced,for the first time,that the melatonin synthesizing enzymes and melatonin receptor were presented in the thyroid tissue,and thyroid gland was able to synthesize and secret melatonin autonomously in sheep.The data provided new evidence for a putative novel intrathyroidal regulatory pathway that melatonin might be involved in thyroid-hormone synthesis.

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