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Possible Involvement of the Rat Hypothalamo‐Neurohypophysial/‐Spinal Oxytocinergic Pathways in Acute Nociceptive Responses
Author(s) -
Matsuura T.,
Kawasaki M.,
Hashimoto H.,
Yoshimura M.,
Motojima Y.,
Saito R.,
Ueno H.,
Maruyama T.,
Ishikura T.,
Sabanai K.,
Mori T.,
Ohnishi H.,
Onaka T.,
Sakai A.,
Ueta Y.
Publication year - 2016
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/jne.12396
Subject(s) - parvocellular cell , oxytocin , medicine , spinal cord , endocrinology , nociception , supraoptic nucleus , hypothalamus , medulla , saporin , magnocellular cell , chemistry , neuroscience , biology , receptor , biochemistry , immunotoxin , cytotoxicity , in vitro
Oxytocin ( OXT )‐containing neurosecretory cells in the parvocellular divisions of the paraventricular nucleus ( PVN ), which project to the medulla and spinal cord, are involved in various physiological functions, such as sensory modulation and autonomic processes. In the present study, we examined OXT expression in the hypothalamo‐spinal pathway, as well as the hypothalamo‐neurohypophysial system, which includes the magnocellular neurosecretory cells in the PVN and the supraoptic nucleus ( SON ), after s.c. injection of saline or formalin into the hindpaws of transgenic rats that express the OXT and monomeric red fluorescent protein 1 ( mRFP 1) fusion gene. (i) The numbers of OXT ‐ mRFP 1 neurones that expressed Fos‐like immunoreactivity (‐IR) and OXT ‐ mRFP 1 intensity were increased significantly in the magnocellular/parvocellular PVN and SON after s.c. injection of formalin. (ii) OXT ‐ mRFP 1 neurones in the anterior parvocellular PVN , which may project to the dorsal horn of the spinal cord, were activated by s.c. injection of formalin, as indicated by a significant increases of Fos‐IR and mRFP 1 intensity intensity. (iii) Formalin injection caused a significant transient increase in plasma OXT . (iv) OXT , mRFP 1 and corticotrophin‐releasing hormone mRNA s in the PVN were significantly increased after s.c. injection of formalin. (v) An intrathecal injection of OXT ‐saporin induced hypersensitivity in conscious rats. Taken together, these results suggest that the hypothalamo‐neurohypophysial/‐spinal OXT ergic pathways may be involved in acute nociceptive responses in rats.