Development of ventilatory long-term facilitation is dependent on estrous cycle stage in adult female rats

Age and the estrus cycle affect time-dependent respiratory responses to episodic hypoxia in female rats. Respiratory long-term facilitation (LTF) is enhanced in middle-aged vs. young female rats ( 72 ). We tested the hypothesis that phrenic and hypoglossal (XII) LTF are diminished in acyclic geriatric rats when fluctuating sex hormone levels no longer establish conditions that enhance LTF. Chronic intermittent hypoxia (CIH) enhances LTF ( 41 ); thus we further predicted that CIH would restore LTF in geriatric female rats. LTF was measured in young (3-4 mo) and geriatric (20-22 mo) female Sasco Sprague-Dawley rats and in a group of geriatric rats exposed to 1 wk of nocturnal CIH (11 vs. 21% O2 at 5-min intervals, 12 h/night). In anesthetized, paralyzed, vagotomized, and ventilated rats, time-dependent hypoxic phrenic and XII responses were assessed. The short-term hypoxic response was measured during the first of three 5-min episodes of isocapnic hypoxia (arterial Po2 35-45 Torr). LTF was assessed 15, 30, and 60 min postepisodic hypoxia. Phrenic and XII short-term hypoxic response was not different among groups, regardless of CIH treatment ( P > 0.05). LTF in geriatric female rats was smaller than previously reported for middle-aged rats but comparable to that in young female rats. CIH augmented phrenic and XII LTF to levels similar to those of middle-aged female rats without CIH ( P < 0.05). The magnitude of phrenic and XII LTF in all groups was inversely related to the ratio of progesterone to estradiol serum levels ( P < 0.05). Thus CIH and sex hormones influence the magnitude of LTF in geriatric female rats.

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Effects of psychotropic drugs on the estrous cycle of female rats modified by the long term appetitive competition

The Japanese Journal of Pharmacology ◽

10.1016/s0021-5198(19)67495-0 ◽

1979 ◽

Vol 29 ◽

pp. 198

Author(s):

Chiaki Hara ◽

Nobuya Ogawa

Keyword(s):

Estrous Cycle ◽

Psychotropic Drugs ◽

Female Rats

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Activities of the pituitary–adrenal and gonadal axes during the estrous cycle in adult female rats prenatally exposed to morphine

Brain Research ◽

10.1016/s0006-8993(01)02339-3 ◽

2001 ◽

Vol 902 (1) ◽

pp. 66-73 ◽

Cited By ~ 6

Author(s):

Isabelle Dutriez-Casteloot ◽

Valérie Montel ◽

Dominique Croix ◽

Christine Laborie ◽

Gilles Van Camp ◽

...

Keyword(s):

Estrous Cycle ◽

Adult Female ◽

Female Rats ◽

Prenatally Exposed

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Comparison of long-term feeding pattern between male and female Fischer 344 rats: influence of estrous cycle

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1996.270.2.r413 ◽

1996 ◽

Vol 270 (2) ◽

pp. R413-R419 ◽

Cited By ~ 12

Author(s):

A. Laviano ◽

M. M. Meguid ◽

J. R. Gleason ◽

Z. J. Yang ◽

T. Renvyle

Keyword(s):

Weight Gain ◽

Food Intake ◽

Estrous Cycle ◽

Meal Size ◽

Female Rats ◽

Fischer 344 Rats ◽

Male And Female ◽

Fischer 344 ◽

Males And Females

We studied the effect of gender on food intake, meal number, and meal size in eight 10-wk-old female and seven age-matched male Fischer 344 rats for 44 consecutive days. Although food intake (g/100 g body wt) was similar in males and females (5.42 +/- 0.10 vs. 5.13 +/- 0.13 g food.day-1.100 g body wt-1, respectively; not significant), weight gain in males was approximately seven times greater than in female rats (1.49 +/- 0.07 vs. 0.21 +/- 0.03 g/day, respectively; P < 0.001). During this time, males had a relatively constant food intake. They increased their meal size but decreased their meal number. In female rats, food intake was relatively stable for the duration of the study, despite cyclically and reciprocally recurring changes in meal number and meal size, which are synchronized with the estrous cycle. Data confirm that net food intake is a dynamic process and suggest that, in the rat, the homeostasis of food intake in response to external as well as internal stimuli is maintained via the modulation of meal number and size.

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A Quantitative Immunocytochemical Study of the Luteinizing Hormone and Follicle-Stimulating Hormone Cells in the Adenohypophysis of Adult Male Rats and Adult Female Rats throughout the Estrous Cycle*

Endocrinology ◽

10.1210/endo-113-3-970 ◽

1983 ◽

Vol 113 (3) ◽

pp. 970-984 ◽

Cited By ~ 37

Author(s):

M. O. DADA ◽

G. T. CAMPBELL ◽

C. A. BLAKE

Keyword(s):

Luteinizing Hormone ◽

Estrous Cycle ◽

Adult Female ◽

Adult Male ◽

Follicle Stimulating Hormone ◽

Female Rats ◽

Male Rats ◽

Immunocytochemical Study ◽

Stimulating Hormone

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IMPAIRMENT OF THE CONTROL OF GONADOTROPHIN SECRETION AFTER OESTROGEN ADMINISTRATION TO ADULT FEMALE RATS

Journal of Endocrinology ◽

10.1677/joe.0.0730497 ◽

1977 ◽

Vol 73 (3) ◽

pp. 497-505 ◽

Cited By ~ 9

Author(s):

K. BROWN-GRANT ◽

M. B. TER HAAR

Keyword(s):

Adult Female ◽

Female Rats ◽

Postnatal Life ◽

Normal Female ◽

Control Mechanisms ◽

Plasma Prolactin ◽

Gonadotrophin Secretion ◽

Significant Impairment ◽

Long Acting

SUMMARY The possible occurrence of long-term changes in gonadotrophin control mechanisms following the administration of oestrogen to adult female rats has been studied. Administration of 2·5 mg oestradiol benzoate (OB) to normal female rats at 60 days of age did not result in failure of ovulation at 120 days of age but significant impairment of the LH and FSH responses to progesterone after ovariectomy and oestrogen priming was observed at 160–180 days of age. Treatment with the same dose of OB at 60 days of rats injected with 10 μg testosterone propionate on Day 4 of postnatal life resulted in an increased incidence of failure of ovulation at 120 though not at 150 days of age but did not further impair the already reduced gonadotrophin response to progesterone at 160–180 days of age. Removal of the ovaries at 60 days of age did not modify the effects of oestrogen given at 60 days of age in either group nor did ovariectomy at 60 days improve the response of neonatally androgen-treated rats to progesterone at 160–180 days of age. The increases in plasma prolactin and TSH levels in response to oestrogen priming after ovariectomy were not affected in any of the experimental groups. The administration of a long-acting oestrogen preparation (oestradiol cyclopentyl propionate, 2·5 mg at 60 days of age) to normal female rats suppressed ovulation and depressed plasma LH and FSH concentrations for at least 90 days; anterior pituitary weights were greatly increased and plasma prolactin concentrations were very high.

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