Increasing Concentrations of 17β-Estradiol Has Differential Effects on Secretion of Luteinizing Hormone and Follicle-Stimulating Hormone and Amounts of Mrna for Gonadotropin Subunits During the Follicular Phase of the Bovine Estrous Cycle1

A normal menstrual cycle is the end result of a sequence of purposeful and coordinated events that occur from intact hypothalamic-pituitary-ovarian and uterine axes. The menstrual cycle is under hormonal control in the reproductively active female and is functionally divided into two phases: the proliferative or follicular phase and the secretory or luteal phase. This tight hormonal control is orchestrated by a series of negative and positive endocrine feedback loops that alter the frequency of the pulsatile secretion of gonadotropin-releasing hormone (GnRH), the pituitary response to GnRH, and the relative secretion of luteinizing hormone and follicle-stimulating hormone from the pituitary gonadotrope with subsequent direct effects on the ovary to produce a series of sex steroids and peptides that aid in the generation of a single mature oocyte and the preparation of a receptive endometrium for implantation to ensue. Any derailment along this programmed pathway can lead to an abnormal menstrual cycle with subsequent impact on the ability to conceive and maintain a pregnancy. This review contains 7 figures and 26 references Key words: follicle-stimulating hormone, follicular phase, gonadotropin-releasing hormone, luteal phase, luteinizing hormone, menstrual cycle, ovulation, progesterone, proliferative phase, secretory phase

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Effects of high levels of body condition and food intake on plasma follicle stimulating hormone, luteinizing hormone, prolactin and progesterone profiles around mating in Greyface ewes

Animal Science ◽

10.1017/s0003356100018377 ◽

1986 ◽

Vol 43 (1) ◽

pp. 101-107 ◽

Cited By ~ 13

Author(s):

S. M. Rhind ◽

I. D. Leslie ◽

R. G. Gunn ◽

J. M. Doney

Keyword(s):

Luteinizing Hormone ◽

Body Condition ◽

Luteal Phase ◽

Weight Maintenance ◽

Follicle Stimulating Hormone ◽

Live Weight ◽

Follicular Phase ◽

High Group ◽

High Level ◽

Stimulating Hormone

ABSTRACTTwo groups of 19 Border Leicester cf × Scottish Blackface 9 ewes were fed so that ewes of one group were in a very high level of body condition at mating (mean score 3·35) and had a high level of intake. Ewes of the second group were in moderately high condition (mean score 2·74) and were given a live-weight maintenance ration. Ewes in the high group had a higher ovulation rate than those of the moderate group (3·36 v. 2·33) but a lower number of embryos per ewe mated (1·16 v. 1·42). Mean follicle stimulating hormone profiles were similar for ewes of the two groups during the luteal and follicular phases of the cycle before mating and during the subsequent oestrus. Mean prolactin concentrations were higher in ewes of the high group during the follicular phase and oestrus but not during the luteal phase. Mean luteinizing hormone (LH) concentrations were higher in ewes of the high group during the follicular phase and oestrus but not during the luteal phase. Mean LH concentrations were similar for the two groups at all times but the frequency of LH pulses was higher in the high group during the follicular phase.Ewes that were not pregnant at slaughter had abnormal progesterone profiles following mating, abnormal pre-ovulatory LH surges or failed to show oestrus. These abnormalities were not related to gonadotrophin profiles prior to oestrus.

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