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Expression of luteinizing hormone/chorionic gonadotropin receptor in the rat pineal gland
Author(s) -
Itoh Masanori T.,
Hosaka Takeshi,
Takahashi Noriyuki,
Ishizuka Bunpei
Publication year - 2006
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.2006.00329.x
Subject(s) - pineal gland , medicine , pinealocyte , endocrinology , melatonin , biology , luteinizing hormone , melatonin receptor , endocrine gland , gonadotropin , receptor , human chorionic gonadotropin , pituitary gland , hormone
Luteinizing hormone (LH) influences the secretion of melatonin ( N ‐acetyl‐5‐methoxytryptamine) from the pineal gland. The present study examined the possible presence of LH/chorionic gonadotropin (CG) receptor in the pineal gland of adult female rats. Reverse transcriptase‐polymerase chain reaction analyses demonstrated that LH/CG receptor mRNA is expressed in the pineal gland. Western blotting showed that the pineal gland, like the ovary, contains an 80 kDa receptor protein. Immunohistochemistry revealed that LH/CG receptor, arylalkylamine N ‐acetyltransferase (a regulatory enzyme in melatonin biosynthesis) and serotonin (a melatonin precursor) are localized primarily to the same cells of the pineal gland. We further found that the levels of pineal LH/CG receptor protein in normal cycling female rats change significantly during the estrous cycle, being lowest at early metestrus. These results demonstrate that LH/CG receptor is expressed in the pineal gland, primarily in melatonin‐synthesizing cells, namely pinealocytes. Furthermore, it is suggested that LH influences pineal melatonin secretion through binding to this receptor. In addition, LH/CG receptor levels in the pineal gland are regulated during the estrous cycle under normal physiological conditions.