Document Detail

Hypothalamic implants of dilute estradiol fail to reduce feeding in ovariectomized rats.
MedLine Citation:
PMID:  12419399     Owner:  NLM     Status:  MEDLINE    
To investigate further the site where estradiol (E(2)) inhibits food intake, we tested the effects on feeding of subcutaneous and intrahypothalamic implants of 10% E(2) benzoate in cholesterol (CHOL) or CHOL alone. E(2) was implanted subcutaneously in Silastic tubes, and intrahypothalamically via bilateral 29-gauge cannulas into the paraventricular nucleus (PVN) or the medial preoptic area (MPA) of ovariectomized (OVX) Sprague-Dawley and Long-Evans rats. Three-day implant periods followed 3-day baseline periods. Rats were allowed ad libitum access to chow and tap water, and food intake and body weight were measured each day. Subcutaneous 10% E(2) implants in Sprague-Dawley rats reduced food intake 21% on Day 2 and 34% on Day 3 (P's<.01) and decreased 3-day body weight gain 11 g (P<.05). In contrast, 10% E(2) implants in the PVN of Sprague-Dawley rats did not change food intake or body weight. Implants of 10% or 20% E(2) in the MPA also failed to decrease food intake. MPA implants of 10% E(2) decreased body weight gain 8 g (P<.05), but MPA implants of 20% E(2) decreased weight gain only 4 g (P>.05). To determine whether the strain of rat affected our negative results on food intake, we implanted 10% E(2) into the PVN of Long-Evans rats. Again, PVN E(2) did not decrease food intake significantly in comparison to the pretest baseline. PVN E(2) did, however, decrease body weight gain 5 g and decreased food intake 6% compared to rats with implants of CHOL (both P<.05), but these effects appeared to be due to an increase in feeding in the CHOL group in comparison to their baseline. Finally, CHOL and E(2) implants did not impair the responsivity of the PVN because acute implants of norepinephrine (NE) into the PVN of E(2)- or CHOL-treated Long-Evans rats significantly increased food intake. Our results do not support the hypothesis that E(2)'s actions in either the PVN or the MPA are sufficient to account for its inhibitory effects on feeding.
Brian J Hrupka; Gerard P Smith; Nori Geary
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Physiology & behavior     Volume:  77     ISSN:  0031-9384     ISO Abbreviation:  Physiol. Behav.     Publication Date:  2002 Nov 
Date Detail:
Created Date:  2002-11-06     Completed Date:  2003-04-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0151504     Medline TA:  Physiol Behav     Country:  United States    
Other Details:
Languages:  eng     Pagination:  233-41     Citation Subset:  IM    
Department of Psychiatry, Joan and Sanford I. Weill Medical College of Cornell University, New York, College of Cornell, New York, NY, USA.
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MeSH Terms
Body Weight / drug effects
Drug Implants
Eating / drug effects*
Estradiol / administration & dosage,  pharmacology*
Hypothalamus / physiology*
Paraventricular Hypothalamic Nucleus / physiology
Preoptic Area / physiology
Rats, Long-Evans
Rats, Sprague-Dawley
Receptors, Estrogen / metabolism
Ventromedial Hypothalamic Nucleus / physiology
Grant Support
Reg. No./Substance:
0/Drug Implants; 0/Receptors, Estrogen; 50-28-2/Estradiol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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