Reduced ovarian follicular development as a consequence of low body condition in ewes

McNeilly, A. S.; Jonassen, Julie A.; Rhind, S. M.

doi:10.1530/acta.0.1150075

Cited by 25 publications

(8 citation statements)

References 22 publications

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“…Adult ewes maintained on low planes of nutrition exhibited reduced ovulation rates (Haresign, 19811, a response attributed to reduced ovarian follicular development (McNeilly et al, 1987) rather than to an alteration of the preovulatory surge of LH. Effects on follicular development could result from disruption of pulsatile LH release.…”

Section: Estrous Cyclementioning

confidence: 99%

Effects of dietary energy on control of luteinizing hormone secretion in cattle and sheep

Schillo

1992

Journal of Animal Science

210

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Prolonged restriction of dietary energy delays onset of puberty, disrupts cyclicity in sexually mature animals, and lengthens the postpartum anestrous period in domestic ruminants. One important mechanism by which energy restriction impairs reproductive activity seems to be suppression of the increase in LH pulse frequency that is necessary for growth of ovarian follicles to the preovulatory stage. Under-nutrition apparently inhibits pulsatile secretion of LH by reducing LHRH secretion by the hypothalamus. The ability of an animal to sustain a high-frequency mode of pulsatile LH release is related to its metabolic status. Mechanisms linking metabolic status to LHRH secretion have not been fully characterized. Changes in body fat have been associated with changes in reproductive activity, but it is unlikely that body fat per se regulates LHRH secretion. It is possible that pulsatile LHRH release is regulated by specific metabolites and(or) metabolic hormones that reflect nutritional status. Alternatively, availability of oxidizable metabolic fuels, such as glucose and nonesterified fatty acids, may influence activity of neurons that control LHRH release. Our understanding of how the central nervous system transduces information about nutritional status into neuroendocrine signals that control reproduction in cattle and sheep is limited by a lack of information concerning the nature of neurons controlling LHRH release in these species.

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Section: Estrous Cyclementioning

confidence: 99%

Effects of dietary energy on control of luteinizing hormone secretion in cattle and sheep

Schillo

1992

Journal of Animal Science

210

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“…Previous studies have shown that in follicles >2.5 mm in diameter, the size beyond which follicles are gonadotrophin dependent in sheep (McNeilly et al . 1986, 1987, McNeilly & Fraser 1987), FF levels of E 2 directly reflect the state of health or atresia of follicles (Carson et al . 1981).…”

Section: Introductionmentioning

confidence: 99%

“…1981). High levels of E 2 reflect healthy preovulatory follicles expressing high levels of LH receptors in both GCs and TCs (Webb & England 1982), and this is correlated with high output of E 2 when the individual follicles are incubated in vitro (Webb & England 1982, McNeilly & Fraser 1987, McNeilly et al . 1987).…”

Section: Introductionmentioning

confidence: 99%

Activin B is produced early in antral follicular development and suppresses thecal androgen production

Young¹,

Henderson²,

Souza³

et al. 2012

Reproduction

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Little is known about the role of activin B during folliculogenesis. This study investigated the expression levels of activin/inhibin subunits (βA, βB, and α), steroid enzyme, and gonadotrophin receptors in theca (TC) and granulosa cells (GC) by QPCR and activin A and B and inhibin A protein levels in follicular fluid (FF) of developing sheep follicles during estrus and anestrus. The effect of activin B on androgen production from primary TC cultures in vitro was also assessed. During folliculogenesis, in anestrus and estrus, FF activin B concentrations and thecal and GC activin βB mRNA levels decreased as follicle diameter increased from 1–3 to >6 mm regardless of estrogenic status. Estrogenic preovulatory follicles had reduced concentrations of FF activins B and A, and TC and GCs expressed higher levels of activin βA mRNA at 3–4 mm, and TCs more inhibin α mRNA at >4 mm stages of development compared with nonestrogenic follicles. Activin B decreased androstenedione production from primary TCs in vitro, an effect blocked by inhibin A. Thus, sheep follicles 1–3 mm in diameter contained high FF levels of activin B, which decreased as the follicle size increased, and, like activin A, suppressed thecal androgen production in vitro, an effect blocked by inhibin. Furthermore, the theca of large estrogenic follicles expressed high levels of inhibin α and activin βA mRNA suggesting local thecal derived inhibin A production. This would inhibit the negative effects of thecal activins B and A ensuring maximum androgen production for enhanced estradiol production by the preovulatory follicle(s).

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“…While the effects of higher levels of body condition have been shown to be expressed, at least in part, through an increased population of large, potentially ovulatory, ovarian follicles around the time of mating (McNeilly et al 1987), increased levels of food intake before mating do not result in any difference in numbers of large follicles (Rhind & McNeilly 1998). Thus, the differences in ovulation rate associated with the level of food intake must be a function of changes in ovarian activity and in the final processes of oocyte maturation.…”

Section: Introductionmentioning

confidence: 99%

Effects of pre-mating nutrition on mRNA levels of developmentally relevant genes in sheep oocytes and granulosa cells

Pisani¹,

Abednatanzi²,

Pocar³

et al. 2008

Reproduction

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The present study was designed to investigate the relationship between pre-mating nutrition and the relative amounts of a panel of developmentally relevant genes in ovine oocytes and granulosa cells. Cast age ewes were fed a ration providing 0.5! (0.5 M) or 1.5! (1.5 M) live weight maintenance requirements for 2 weeks before slaughter. The ewes were synchronized and superovulated with FSH and pregnant mares serum gonadotropin. At slaughter, oocytes and granulosa cells were aspirated from follicles O2 mm in diameter and the relative abundance of 8 and 17 transcripts in oocytes and granulosa cells respectively were analyzed by semi-quantitative RT-PCR. In the oocytes, no differences between groups were observed for five transcripts (GDF9, BMP15, c-kit, glucose transporter 1 (SLC2A1), and hexokinase 1), but a lower amount of glucose transporter 3 (SLC2A3), sodium/glucose cotransporter 1 (SLC5A1), and Na C /K C ATPase mRNAs was detected in the 0.5 M group. Increased expression of PTGS2, HAS2, and the leptin receptor long form was observed in granulosa cells from the 0.5 M group. No differences between groups were observed for the other transcripts (early growth response factor-1, estrogen receptor-a, LH and FSH receptors, gremlin 1, pentraxin 3, KIT ligand, glucose transporters 1, 3, and 8, IGF1, IGF1 receptor, leptin receptor, and tumor necrosis factor-stimulated gene 6). Expression of leptin and sodium/glucose cotransporter 1 was not detected in both groups. The present data indicate that pre-mating nutrition is associated with alteration in the mRNA content in oocytes and surrounding follicle cells in ewes, which may account for the reduced reproductive performance typical of ewes that are fed a restricted ration for a short period of time before mating.

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Reduced ovarian follicular development as a consequence of low body condition in ewes

Cited by 25 publications

References 22 publications

Effects of dietary energy on control of luteinizing hormone secretion in cattle and sheep

Effects of dietary energy on control of luteinizing hormone secretion in cattle and sheep

Activin B is produced early in antral follicular development and suppresses thecal androgen production

Effects of pre-mating nutrition on mRNA levels of developmentally relevant genes in sheep oocytes and granulosa cells

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