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Role of light in the estrogen deficiency‐induced changes in diurnal SCN neural activity and food intake
Author(s) -
Miyake Kana,
Morimoto Keiko,
Takamata Akira
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.1033.1
Subject(s) - endocrinology , medicine , suprachiasmatic nucleus , circadian rhythm , ovariectomized rat , food intake , estrogen , chemistry , hypothalamus
To test the hypothesis that light exposure plays an important role in estrogen (E2) deficiency‐induced decrease in neuronal activity of the suprachiasmatic nucleus (SCN) and increase in food intake during light phase, we examined the effect of E2 replacement in ovariectomized rats on food intake, body temperature, and c‐Fos expression under different light exposure schedule. Rats were ovariectomized and implanted subcutaneously either with 17β‐estradiol or vehicle (cholesterol), and experiments were conducted 2 weeks after the implantation. Rats were maintained under 12h/12h‐light/dark condition (LD), followed by exposed to dark/dark condition (DD), and food intake and body temperature were measured throughout the experiments. Exposure to DD increased body temperature and food intake during daytime in E2‐replaced rats, but not in E2 deficit rats. The number of c‐Fos immunoreactive cells was significantly decreased in daytime with DD only in E2‐replaced rats. The data indicate that E2 elevates sensitivity of SCN neurons to light, resulting in enhancement of the amplitude of circadian variations of food intake and body temperature.