Solicitation behavior in the estrous female rat: a review

Hormone-neurotransmitter interactions in the control of sexual behavior.

Plasma levels of luteinizing hormone (LH) progesterone and estrogen were determined in pregnant and nonpregnant cycles of female beagle dogs. Mean basal LH levels during estrus and proestrus were 1.4 + or -.1 ng/ml and peaked at 7.5 + or -.8 ng/ml on the 1st day of estru s. Preovulatory increases in progesterone and LH appeared to be temporally correlated and were significantly elevated by the 2nd day of estrus (p less than .001). Progesterone levels reached their maximum on the 25th day of estrus (22.9 + or -2.7). Estrogen levles increased from 26 + or -4 on Day 10 prior to the LH peak to 62 + or -4 pg/ml 1 day before the LH peak. Once the LH peak was established estrogen levels fell rapidly. In the luteal phases of 12 pregnant and 10 nonpregnant cycles there were no marked differences in mean maximum progesterone levels the ranges of individual maximum levels or the time of their occurrence. After Day 30 progesterone levels declined gradually and were significantly (p less than .001) variable in nonpregnant cycles compared with pregnant cycles once progesterone levels dropped below 1 ng/ml. Progesterone levels showed significant (p less than .05) daily changes during the 2 days prior to parturition. Plasma Estrogen levels were constant in nonpregnant cycles but significantly (p less than .01) increased during the 3 weeks prior to parturition. The results suggest that plasma estrogen initiates or potentiates the preovulatory release of LH that the early preovulatory release of progesterone may encourage the LH peak surge and the onset of behavioral estrus and that mechanisms exist that maintain elevated levels of plasma progesterone throughout pregnancy.

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The Ovarian Cycle of the Bitch: Plasma Estrogen, LH and Progesterone

/pdf/hormonal-control-of-lactation-39bekhhu1g.pdf

Hormonal Control of Lactation

Sexual stimulation activates c-fos within estrogen-concentrating regions of the female rat forebrain.

Follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin concentrations were determined by radioimmunoassay (NIAMD-Rat RIA) of sera from intact hamsters, which were decapitated at selected times during the 4-day estrous cycle. Serum FSH concentrations on Day 1 of the cycle (day of ovulation) were 2- to 6-fold greater than the levels on Day 2 and 5 to 12-fold greater than the mean, “basal,” level of FSH (53 ± 2 ng/ml; 80 hamsters) found during Day 3 and until 1200 hr, Day 4. There was a biphasic serum FSH pattern on Day 4 (proestrus) which was demarcated by the initiation of the preovulatory surge at 1400 hr, the peak level at 1600 hr, the decay of the surge by 2100 hr, and the subsequent elevation to the high levels present on Day 1. In marked contrast to these changes in serum levels of FSH, LH levels were virtually constant throughout the estrous cycle, except for the preovulatory surge between 1300 hr and 1900 hr on Day 4 with a peak level at 1600 hr. Prolactin concentrations varied a...

Serum profiles of follicle-stimulating hormone, luteinizing hormone and prolactin during the estrous cycle of the hamster.

The occurrence of ovulation and serum levels of LH and FSH (measured by radioimmunoas- say) were determined in periovulatory hamsters injected with an ovulation-blocking dose of phenobarbital (Phen) combined with progesterone (P), estradiol-17β(E2), or testosterone (T). Proestroush amsters were treated at 1300 h with Phen plus oil, P, P plus E2, E2, T, or a second injection of Phen at 2000 h. Each treatment group was divided into 3 subgroups, each of which was serially bled 4 times at 6 h intervals beginning at 1200, 1400, and 1600h on proestrus. Phen blocked ovulation on the next morning in all animals, while treatments that included P (1 mg) restored the normal complement of ova in 65–75% of the animals. Neither E2 (1, 10 or 50 μg) nor T (0.1 or 1 mg) overcame the Phen block of ovulation. Control hamsters had peak levels of LH between 1400 and 1800 h and a biphasic release ofFSH consisting of a peak at 1600 h on proestrus, a return to basal levels at 2200 h, and a second more sustained surge between 240...

The effects of phenobarbital and gonadal steroids on periovulatory serum levels of luteinizing hormone and follicle-stimulating hormone in the hamster.

During the normal 4-day estrous cycle of the hamster, 12.0 ± 0.4 (n = 34) ova were shed by the paired ovaries on Day 1. When unilateral ovariectomy (ULO) was performed at 0900 h on any one of the first 3 days of the cycle, approximately the same number of ova were released from the remaining ovary on Day 1 of the ensuing postoperative cycle (compensatory ovulation), except after ULO on Day 4. In view of these results, the principal aim of the present study was to determine if ULO affected acute (24 h postoperative period) and chronic (postoperative cycles) alterations in serum levels of immunoreactive FSH. Multiple bleedings were obtained by cardiac puncture without anesthesia. The acute alteration in FSH levels was first examined at 24-h intervals following ULO at 0930 h on any one day of the cycle, and significant elevations in these levels were found 24 h postoperatively in all but Day-2 hemicastrates. Several experiments were then performed to determine the time-sequence for this 24-h response to ULO....

Acute and Chronic Elevations in Serum Levels of FSH After Unilateral Ovariectomy in the Cyclic Hamster

Lesions in the preoptic area suppressed sexual receptivity in ovariectomized rats with estrogen implants in the ventromedial hypothalamus.

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Joseph D. Bast

Papers

Serum profiles of follicle-stimulating hormone, luteinizing hormone and prolactin during the estrous cycle of the hamster.

The effects of phenobarbital and gonadal steroids on periovulatory serum levels of luteinizing hormone and follicle-stimulating hormone in the hamster.

Acute and Chronic Elevations in Serum Levels of FSH After Unilateral Ovariectomy in the Cyclic Hamster

Lesions in the preoptic area suppressed sexual receptivity in ovariectomized rats with estrogen implants in the ventromedial hypothalamus.

Hormone Patterns in Pregnant or Pseudopregnant Hamsters After Unilateral Ovariectomy or Hysterectomy