Chronic food deprivation-induced suppression of pulsatile luteinizing hormone secretion in the ovariectomized rat /
The effects of chronic food deprivation on pulsatile
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739887871&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The effects of chronic food deprivation on pulsatile luteinizing hormone (LH) secretion were determined in ovariectomized rats. The neuroendocrine pathways involved were also studied. Food deprivation for 96 hours decreased the frequency (p<.001), increased the amplitude (p<.001) and increased the duration (p<.001) between LH pulses. To evaluate the role of visceral signals in chronic food deprivation-induced suppression of LH secretion, 1.0 g of laboratory rat diet was introduced directly into the stomach of food deprived ovariectomized rats. Intragastric infusion of rat chow gruel increased the frequency of LH pulses post- infusion (p<O. 1) as compared to sham and saline infused groups and an increased LH pulse frequency (p<0.05) when compared to pre-infusion LH pulse frequency. To assess the involvement of the gastric vagal branches in chronic food deprivation-induced suppression of LH secretion in ovariectomized rats, the gastric branches of the vagal trunks were transacted the day prior to blood sample collection. Transection of the gastric vagal branches resulted in no difference in mean LH pulse frequency (p>O. 1), amplitude (p>O. 1) or duration (P>O. 1) between chronically food deprived and ad libitum fed animals. Endogenous opioid involvement in chronic food deprivation-induced suppression of LH secretion in ovariectomized rats was assessed by intravenous administration of the opiate receptor blocker naltrexone (2.0 mg/kg). Injection of naltrexone did not influence the frequency (p>O. 1), amplitude (p>O. 1) or duration (p>O. 1) between LH pulses in chronically food deprived or ad libitum fed animals. Intra-peritoneal administration of the serotonin receptor blocker ketanserin (1.0 mg/kg) did not influence LH pulse frequency (p>O. I), amplitude (p>O. 1) or duration (p>O. 1) between LH pulses in chronically food deprived or ad libitum fed rats. Ketanserin increased mean plasma LH concentration (p<0.05) in ad libitum fed animals, and an increased mean depolarization induced release of LHRH from the medial basal hypothalamus (p<0.05) in chronically food deprived animals. The present results suggest chronic food deprivation of 96 hours has a suppressive effect on LH secretion in ovariectomized animals and appears to involve the gastric branches of the vagus nerves and occurs independent of endogenous opiate and serotonergic pathways. |
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| Item Description: | Vita. "Major Subject: Veterinary Anatomy". |
| Physical Description: | xii, 192 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 94-118. |