2005 Fiscal Year Final Research Report Summary
Studies in several central effects of oxytocin in lactating rats
| Project/Area Number |
15590205
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | University of Fukui (2004-2005)
福井医科大学 (2003) |
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Principal Investigator |
MURATA Takuya University of Fukui, Faculty of Medical Science, Associate Professor, 医学部, 助教授 (70281186)
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| Co-Investigator(Kenkyū-buntansha) |
NARITA Kazumi University of Fukui, Faculty of Medical Science, Assistant Professor, 医学部, 助手 (80270958)
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| Project Period (FY) |
2003 – 2005
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| Keywords | oxytocin / estrogen / rats / hypothalamus / feeding / behavior |
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| Research Abstract |
Oxytocin is a hormone which is produced in the paraventricular nucleus and the supraoptic nucleus of hypothalamus and secreted from the posterior pituitary, and has been reported to be also secreted in the brain and involved in the several brain functions. The aim of this study is to investigate the brain functions of oxytocin in feeding and locomotor activity in rats.
First, the effects of oxytocin on neuropeptide-Y (NPY) and agouti-related protein (AgRP)-induced food intake were examined. In Wistar male rats oxytocin (1nmlo/5ul, icv) or saline were injected through the implanted cannula and 30 min later NPY, AgRP (1nmlo/5ul, icv) or saline were injected. After the second injection, food intake was monitored for 1 h and 2 h. Oxytocin did not affect the NPY- and AgRP-induced food intake, but significantly reduced the basal food intake in saline-treated rats.
Next, the effects of oxytocin on the locomotor activity in Wistar male and female rats were examined. When oxytocin was injected in
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to the ventromedial hypothalamus (VMH) of intact male or ovariectomized (OVX) female rats, the locomoter activity monitored in the running wheel significantly increased. This effect of oxytocin in OVX rats was enhanced by the pretreatment with 17β-estradiol (E2). In OVX rats, oxytocin receptor (OTR) mRNA in VMH significantly increased 24 h after E2 treatment, but did not change at 3 h, while the uterine OTRmRNA significantly increased 1 h after the treatment. OTRmRNA in VMH increased on proestrus significantly compared with that on diestrus during the estrous cycle in intact rats. The change of OTRmRNA in VMH is small (about 2 folds) and delayed compared with that in uterus.
These results suggested that the central oxytocin is involved in the regulation of food intake and locomotor activity in rats and that the effect of oxytocin in female rats is enhanced by estrogen through the induction of OTR. This estrogen-induced OTR regulation are observed both in uterus and VMH, but it is possible that there is a different modification in OTR regulation between two mechanisms because of the differences in the amplitude and latency of OTR mRNA increase. Less
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Research Products
(4 results)
