Sex-related differences in the distribution of opioid receptor-like 1 receptor mRNA and colocalization with estrogen receptor mRNA in neurons of the spinal trigeminal nucleus caudalis in the rat
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Flores, CA
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机构:Meharry Med Coll, Dept Anat & Physiol, Nashville, TN 37208 USA
Flores, CA
Shughrue, P
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机构:Meharry Med Coll, Dept Anat & Physiol, Nashville, TN 37208 USA
Shughrue, P
Petersen, SL
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机构:Meharry Med Coll, Dept Anat & Physiol, Nashville, TN 37208 USA
Petersen, SL
Mokha, SS
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机构:Meharry Med Coll, Dept Anat & Physiol, Nashville, TN 37208 USA
Mokha, SS
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[1] Meharry Med Coll, Dept Anat & Physiol, Nashville, TN 37208 USA
[2] Wyeth Ayerst Res, Womens Hlth Res Inst, Radnor, PA 19087 USA
[3] Univ Massachusetts, Dept Biol, Neurosci & Behav Program, Amherst, MA 01003 USA
We recently reported that exogenously applied orphanin FQ, the endogenous ligand for opioid receptor-like 1 (ORL1) receptor, produces sex-specific modulation of trigeminal nociception, and that estrogen contributes to these sex-related differences. Estrogen could produce these sex-related differences by altering the expression of the ORL1-receptor gene in the trigeminal nucleus caudalis. Utilizing in situ hybridization, we compared levels of ORL1 receptor mRNA and investigated its colocalization with estrogen receptor mRNA in trigeminal neurons. Our results showed that in male rats, ORL1 receptor mRNA is abundantly expressed in the rostral part of the trigeminal nucleus caudalis, and at the junction of caudalis and interpolaris (Vc/Vi). In comparison with males, levels of ORL1 receptor mRNA were not significantly different in proestrus females, but were significantly higher in the rostral trigeminal nucleus caudalis and at the junction of Vc/Vi of diestrus females. In addition, ovariectomy raised the levels in the rostral trigeminal nucleus caudalis, and at the junction of Vc/Vi. Levels were reduced to proestrus levels in these regions following estradiol replacement. Our results also showed that ORL1 receptor mRNA is present in majority of estrogen receptor (alpha and/or beta) mRNA-containing neurons. We conclude that there are sex-related differences in the ORL1-receptor gene expression in the trigeminal nucleus caudalis, which appear to be determined in part by estrogen levels. (C) 2003 IBRO. Published by Elsevier Science Ltd. All rights reserved.