Neuronal somatic volume of posteroventral medial amygdala cells from males and across the estrous cycle of female rats

The controls of food intake differ in male and female rats. Daily food intake is typically greater in male rats, relative to female rats, and a decrease in food intake, coincident with the estrous stage of the ovarian reproductive cycle, is well documented in female rats. This estrous-related decrease in food intake has been attributed to a transient increase in the female rat's sensitivity to satiety signals generated during feeding bouts. Here, we investigated whether sex or stage of the estrous cycle modulate the satiety signal generated by fenfluramine, a potent serotonin (5-HT) releasing agent. To examine this hypothesis, food intake was monitored in male, diestrous female, and estrous female rats after intraperitoneal injections of 0, 0.25, and 1.0 mg/kg d-fenfluramine. The lower dose of fenfluramine decreased food intake only in diestrous and estrous females, suggesting that the minimally effective anorectic dose of fenfluramine is lower in female rats, relative to male rats. Although the larger dose of fenfluramine decreased food intake in both sexes, the duration of anorexia was greater in diestrous and estrous female rats, relative to male rats. Moreover, the magnitude of the anorectic effect of the larger dose of fenfluramine was greatest in estrous rats, intermediate in diestrous rats, and least in male rats. Thus our findings indicate that the anorectic effect of fenfluramine is modulated by gonadal hormone status.

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063 — (ROD0183) Voltage oscillations induced by intrahippocampal pilocarpine in female rats during the estrous cycle

Epilepsy & Behavior ◽

10.1016/j.yebeh.2014.08.096 ◽

2014 ◽

Vol 38 ◽

pp. 208-209

Author(s):

M.C.A. Rodrigues ◽

A.R. Isaac ◽

B.L.S. Andrade-da-Costa

Keyword(s):

Estrous Cycle ◽

Female Rats

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Stress Activation of Cortex and Hippocampus Is Modulated by Sex and Stage of Estrus

Endocrinology ◽

10.1210/endo.143.7.8888 ◽

2002 ◽

Vol 143 (7) ◽

pp. 2534-2540 ◽

Cited By ~ 103

Author(s):

Helmer F. Figueiredo ◽

Charles M. Dolgas ◽

James P. Herman

Keyword(s):

Estrous Cycle ◽

Restraint Stress ◽

Piriform Cortex ◽

Lateral Septum ◽

Medial Amygdala ◽

Estrus Cycle ◽

Gonadal Steroid ◽

Disease States ◽

Stress Integration ◽

Stress Activation

Abstract Sex plays a major role in stress integration and stress-related affective disease states. Notably, neurocircuits regulating organismic responses to stress are prime targets for central gonadal steroid action. To assess the roles of sex and estrous cycle in central stress integration, we analyzed c-fos mRNA expression in hypothalamic-pituitary-adrenocortical-related regions of stressed male and cycling female (proestrous, estrous, and diestrous) rats. At 60 min after the onset of acute restraint stress, all animal groups showed induction of c-fos mRNA in the frontal cortex, cingulate cortex, piriform cortex, hippocampus, hypothalamic paraventricular nucleus (PVN), medial amygdala, and lateral septum. However, the magnitude of c-fos induction in cortical and hippocampal regions was substantially lower in proestrous and estrous females compared with males and diestrous females. Sex- and estrus cycle-related changes are region specific, as no difference in c-fos induction occurred in the hypothalamic PVN, medial amygdala, or ventrolateral septum in any group. Furthermore, induction of c-fos mRNA in limbic cortexes (but not hippocampus) was positively correlated with progesterone and negatively correlated with ACTH levels. Taken together, this study indicates that cortical structures are differentially stress activated in females depending on the phase of the estrous cycle, perhaps in a progesterone-dependent fashion.

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Maintenance of Estrous Cycle in Female Rats with Anterior or Posterior Deafferentation of the Suprachiasmatic Nucleus

Neuroendocrinology ◽

10.1159/000124948 ◽

1988 ◽

Vol 47 (5) ◽

pp. 444-452 ◽

Cited By ~ 2

Author(s):

Kouji Nomura ◽

Sumio Takahashi ◽

Seiichiro Kawashima

Keyword(s):

Estrous Cycle ◽

Suprachiasmatic Nucleus ◽

Female Rats

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Estrous cycle influence on individual differences in the response to novelty and cocaine in female rats

Behavioural Brain Research ◽

10.1016/j.bbr.2005.01.004 ◽

2005 ◽

Vol 161 (1) ◽

pp. 69-74 ◽

Cited By ~ 26

Author(s):

Stacy L. Sell ◽

Ashlee M. Dillon ◽

Kathryn A. Cunningham ◽

Mary L. Thomas

Keyword(s):

Individual Differences ◽

Estrous Cycle ◽

Female Rats

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Circadian and estrous cycle-dependent variations in blood pressure and heart rate in female rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1994.267.5.r1250 ◽

1994 ◽

Vol 267 (5) ◽

pp. R1250-R1256 ◽

Cited By ~ 8

Author(s):

H. Takezawa ◽

H. Hayashi ◽

H. Sano ◽

H. Saito ◽

S. Ebihara

Keyword(s):

Heart Rate ◽

Estrous Cycle ◽

Female Rats ◽

Constant Darkness ◽

Dark Phase ◽

Daily Rhythms ◽

Abrupt Decrease ◽

Internal Phase ◽

Free Running ◽

Cycle Dependent

To determine whether cardiovascular functions are controlled by the endogenous circadian system and whether they change with the estrous cycle in female rats, we measured mean arterial pressure (MAP), heart rate (HR), and spontaneous activity (ACT) of female rats using an implantable radiotelemetry device and a computerized data-collecting system. Under a 12:12-h light-dark (LD) cycle, these parameters exhibited daily rhythms that were entrained to the photic cycle. The patterns of the daily rhythms varied with estrous cycles, and variations were particularly marked in the proestrous stage. During the dark period of this stage, ACT levels were significantly higher, but HR was significantly lower than in other stages. Although the peak MAP occurred within 2 h after the onset of the dark phase in three of the estrous stages, it occurred around midnight in the proestrous stage. Such estrous cycle-dependent variations were eliminated by ovariectomy. The implantation of 17 beta-estradiol produced a gradual increase in MAP and an abrupt decrease in HR. During constant darkness, all three parameters were free running, maintaining the same internal phase relationships with each other as during LD cycles. These results indicate that daily variations in these parameters were controlled by the endogenous circadian oscillating system, that they vary with the estrous cycle in female rats, and that estrogen may be responsible for these estrous cycle-dependent variations.

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