A series of experiments was designed to examine the effects of estradiol on the period, phase and the distribution of drinking rhythms in female and male rats. / The results of Experiment I indicated the period ((tau)) of free-running drinking rhythms was not measurably affected by chronic estradiol benzoate (EB) implants in either blind female rats or sighted female rats maintained in dim constant light. The period of activity rhythms of blind rats also was unaffected by EB implants. A more sustained pattern of drinking during alpha ((alpha)) as well as an increase in the daily number of licks were observed in response to estradiol. / In Experiment II, ovariectomized rats received daily injections of estradiol (E) near the onset or end of the drinking rhythm. On a LD10:14 h cycle no changes in the phase angle of entrainment ((PSI)) were observed. However, on a LD10:14.17 h cycle, injections of E before lights-off produced a more negative (PSI) while injections of E after lights-on caused no systematic change in (PSI). Chronic EB treatment induced a more positive (PSI) when rats were entrained to a LD10:14.17 h cycle. These effects suggest that estradiol produces changes in (tau) of the underlying circadian pacemakers. / The results of Experiment III indicated that, as in the hamster, the onset of activity occurs earlier on the day of estrus in the rat. However, while the onset of drinking also occurred earlier on the day of estrus in rats with access to a wheel, the onset of drinking was delayed in rats housed in hanging cages. The most consistent change was a more sustained pattern of drinking or activity on the day of estrus. In addition, a difference in the pattern of entrainment to a LD10:14-17 h cycle between males and females indicated a possible sex difference in the tolerance to (alpha) compression. / The results of Experiment IV indicated that the change in the distribution of drinking during alpha, changes in (PSI), as well as the increase in the daily number of licks following estradiol treatment was attenuated in rats with medial preoptic area lesions. / Compared to the effects of estradiol on circadian rhythms of hamsters reported in the literature, the circadian system of the rat appears to be considerably less sensitive to this hormone. The elucidation of species and sex differences plays an important role in our understanding of the circadian organization and its role in the regulation of physiology and behavior. / Source: Dissertation Abstracts International, Volume: 46-08, Section: B, page: 2860. / Thesis (Ph.D.)--The Florida State University, 1985.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75621 |
| Contributors | ROBBINS, ANN., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 176 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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