Influence of dose, frequency, and duration of infused gonadotropin-releasing hormone on secretion of luteinizing hormone and follicle-stimulating hormone in nutritionally anestrous beef cows

Vizcarra, J. A.; Wettemann, R. P.; Morgan, Gilbert T.

doi:10.1016/s0739-7240(99)00007-7

Cited by 9 publications

(7 citation statements)

References 43 publications

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“…Low P4 levels, combined with increased E2 serum levels and pulsatile GnRH release up-regulates expression of GnRH receptors [32,76], which will make the pituitary more sensitive to GnRH. GnRH pulsatility is important because prolonged constant GnRH exposure leads to down-regulation of GnRH receptor [76,77]. GnRH pulse frequency affects height of the LH peak [76], and also treatment with a single GnRH injection can increase LH peak height [14].…”

Section: Gonadotropin Releasing Hormonementioning

confidence: 99%

A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

Bôer

Stötzel

Röblitz

et al. 2011

Journal of Theoretical Biology

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Bovine fertility is the subject of extensive research in animal sciences, especially because fertility of dairy cows has declined during the last decades. The regulation of estrus is controlled by the complex interplay of various organs and hormones. Mathematical modeling of the bovine estrous cycle could help in understanding the dynamics of this complex biological system. In this paper we present a mechanistic mathematical model of the bovine estrous cycle that includes the processes of follicle and corpus luteum development and the key hormones that interact to control these processes. The model generates successive estrous cycles of 21 days, with three waves of follicle growth per cycle. The model contains 12 differential equations and 54 parameters. Focus in this paper is on development of the model, but also some simulation results are presented, showing that a set of equations and parameters is obtained that describes the system consistent with empirical knowledge. Even though the majority of the mechanisms that are included in the model are based on relations that in literature have only been described qualitatively (i.e. stimulation and inhibition), the output of the model is surprisingly well in line with empirical data. This model of the bovine estrous cycle could be used as a basis for more elaborate models with the ability to study effects of external manipulations and genetic differences. AMS MSC 2000: 92C42, 92C30, 90C31, 65L09

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Section: Gonadotropin Releasing Hormonementioning

confidence: 99%

A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

Bôer

Stötzel

Röblitz

et al. 2011

Journal of Theoretical Biology

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“…Other G values were G(2) ϭ 3.6, G(3) ϭ 2.9, G(4) ϭ 2.5, and G(5) ϭ 2.1. Additionally, time-series analysis [22] and the mean Ϯ 1 SD [23] were used to evaluate LH, FSH, and testosterone pulse frequency. Pulse amplitude was defined as the difference between the greatest value during the pulse and the nadir within 30 min before the pulse.…”

Section: Hormone Assaysmentioning

confidence: 99%

Episodic Gonadotropin Secretion in the Mature Fowl: Serial Blood Sampling from Unrestrained Male Broiler Breeders (Gallus domesticus)1

Vizcarra

Kreider

Kirby

2004

Biology of Reproduction

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Forty-week-old male broiler breeders were used in two experiments. Males were reared as recommended by the breeder, housed in individual cages, and cannulated to facilitate blood sampling. In experiment 1, blood samples were collected at 10- min intervals for 4 h commencing the day of cannulation (Day 0) and for 12 h on each of Days 1 and 2. In experiment 2, blood samples were collected at 10-min intervals for 8 h on Day 1. After centrifugation, plasma was stored at -20 degrees C until LH, FSH (experiment 1 and 2), testosterone, and corticosterone (experiment 1) concentrations were determined by RIA. Different statistical methods used to identify hormone secretion profiles revealed a characteristic pulsatile pattern of LH and FSH in plasma. However, LH pulses were more frequent and had greater amplitude than FSH pulses. Less than 32% of the FSH pulses were associated with LH episodes. Conversely, the association between LH and testosterone pulses averaged 83% in birds with testis weight greater than 10 g. Concentrations of corticosterone tended to increase after cannulation and remained elevated for only 3-4 h. Our data indicate that LH, FSH, and testosterone secretion is pulsatile in male broiler breeders. Additionally, LH pulses are associated with testosterone episodes but not with FSH pulses. The pulsatile pattern of FSH secretion, which is unique from those of LH, in adult males suggests that FSH secretion is independently regulated in the adult male fowl.

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“…At higher doses of GnRH (4 µg) a downregulation of the LH and FSH responses occurred with LH and FSH release only occurring on the 1 st and 3 rd days of treatment (Vizcarra et al, 1999). These studies suggest that concentrations of LH and FSH in blood of cows, and the ratio of LH to FSH, can be altered by the frequency and amount of GnRH stimulation.…”

Section: (1998) a S S I G N E D P O S T -P A R T U M B E E F C O W S mentioning

confidence: 70%

Relative Roles of FSH and LH in Stimulation of Effective Follicular Responses in Cattle

Crowe¹,

Mullen²

2013

Gonadotropin

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Influence of dose, frequency, and duration of infused gonadotropin-releasing hormone on secretion of luteinizing hormone and follicle-stimulating hormone in nutritionally anestrous beef cows

Cited by 9 publications

References 43 publications

A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

A simple mathematical model of the bovine estrous cycle: Follicle development and endocrine interactions

Episodic Gonadotropin Secretion in the Mature Fowl: Serial Blood Sampling from Unrestrained Male Broiler Breeders (Gallus domesticus)1

Relative Roles of FSH and LH in Stimulation of Effective Follicular Responses in Cattle

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