Relationship between pituitary GnRH-binding sites and pituitary release of gonadotrophins in post-partum beef cows

Leung, Kwanyee; Padmanabhan, Vasantha; Spicer, L. J.; Tucker, Heather; Short, R. E.; Convey, E. M.

doi:10.1530/jrf.0.0760053

Cited by 15 publications

(10 citation statements)

References 17 publications

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“…32 Dominant follicles of larger diameter may have developed with increasing post-partum interval since an increase in the diameter of dominant follicles has been observed with increasing post-partum interval in dairy cows. 33 An increase in the amplitudes of LH pulses has been detected in cattle between Days 7 and 28 postpartum, 34,35 while a 4-fold increase in intrafollicular concentrations of oestradiol in large ovarian follicles has been detected in anoestrous beef cows between Days 14 and 28 post-partum. 36 Taken together, the results of other studies would suggest that cows with longer post-partum intervals could have larger diameter, more oestrogen-active dominant follicles, which secreted more oestradiol earlier in pro-oestrus.…”

Section: Discussionmentioning

confidence: 99%

Synchronisation of oestrus and reproductive performance of dairy cows following administration of oestradiol benzoate or gonadotrophin releasing hormone during a synchronised pro‐oestrus

Cavalieri

Macmillan

2002

Aust Veterinary J

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Section: Discussionmentioning

confidence: 99%

Synchronisation of oestrus and reproductive performance of dairy cows following administration of oestradiol benzoate or gonadotrophin releasing hormone during a synchronised pro‐oestrus

Cavalieri

Macmillan

2002

Aust Veterinary J

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“…These differences do not seem to be related to suckling, pituitary LH content, hypothalamic GnRH content or pituitary GnRH receptors (Nancarrow and Radford, 1977;Webb et al. 1977;Radford et al, 1978;Short et al, 1979;Foster et al, 1980;Irvin et al, 1981a,b;Smith et al, 1981;Wettemann et al, 1982;Williams et al, 1982a;Stevenson et al, 1983;Peters, 1984b;Allrich et al, 1985;Hinshelwood et al, 1985;Moss et al, 1985;Schallenberger and Prokopp, 1985;Leung et al, 1986;Jaeger et al, 1987;Weesner et al, 1987;Nett et al, 1988). However, these negative effects are not sustained and do not appear to account for the normal delay in resumption of estrous cycles observed in the suckled postpartum beef cow .…”

Section: Control Mechnnlrms Of Postpartum Anestrusmentioning

confidence: 99%

Physiological mechanisms controlling anestrus and infertility in postpartum beef cattle.

Short

Bellows

Staigmiller

et al. 1990

Journal of Animal Science

469

249

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Postpartum infertility is caused by four factors: general infertility, lack of uterine involution, short estrous cycles and anestrus. The general infertility component is common to any estrous cycle and reduces potential fertility by 20 to 30%. Incomplete uterine involution prevents fertilization during the first 20 d after calving but is not related to anestrus. Short estrous cycles prevent fertility during the first 40 d after calving by causing the cow to return to estrus before pregnancy recognition occurs. Anestrus is the major component of postpartum infertility and is affected by several minor factors: season, breed, parity, dystocia, presence of a bull, uterine palpation and carryover effects from the previous pregnancy as well as two major factors: suckling and nutrition. These major factors have direct effects on anestrus but also interact with one or more other factors to control postpartum anestrus. Physiological mechanisms associated with anestrus involve blockage of the GnRH "pulse generator" in the hypothalamus, but other pathways also must be involved because bypassing the pulse generator is not an effective treatment for all cows. The primary cause of anestrus probably is different for different stages of anestrus. The mediating mechanisms for anestrus are not involved with prolactin, oxytocin, the adrenal or direct neural input from the mammary gland but are at least partially involved with blood glucose and the endogenous opioid peptide system. Management options to decrease the impact of anestrus and infertility include: 1) restrict breeding season to less than or equal to 45 d; 2) manage nutrition so body condition score is 5 to 7 before calving; 3) minimize effects of dystocia and stimulate estrous activity with a sterile bull and estrous synchronization; and 4) judicious use of complete, partial or short-term weaning.

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“…Animals. Brain tissues were obtained from 30 postpartum beef cows used in an experiment described in detail by Leung et al (1986). The cows were approximately 3 yr old at parturition, which occurred between July 1 and 24, 1982.…”

Section: Methodsmentioning

confidence: 99%

“…ings et al, 1980Peters and Lamming, 1984;Schallenberger, 1985). Early during the postpartum period (i.e., 10 to 20 d), LH secretion seems to be low due to a deficiency in pituitary secretory capacity, as demonstrated by reduced LH responses to gonadotropin-releasing hormone (GnRH) when administered either in vivo (Webb et al, 1977, Inskeep andLishman, 1979) or in vitro (Moss et al, 1985;Leung et al, 1986). This deficiency in LH secretory capacity is related to reduced content of LH in the pituitary and not to any reduction in binding sites for GnRH (Moss et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

Quantification of Naloxone Binding Sites in Brains from Suckled Beef Cows during Postpartum Anestrus and Resumption of Estrous Cycles

Trout

Malven

1988

Journal of Animal Science

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Thirty beef cows, approximately 3 yr of age, were randomly assigned to be slaughtered on d 7, 14, 28, 42 or 56 postpartum. Each cow suckled one calf until slaughter. Data from cows slaughtered on d 42 and 56 were pooled and further classified as anestrous or cyclic based on the presence of a corpus luteum and elevated serum concentrations of progesterone at slaughter. Specific binding of [3H]naloxone (3H-NAL) to homogenates of tissue from hypothalamus (HYP), preoptic area (POA) and basal forebrain (BF) was assessed using multiple-point Scatchard analyses. Nonspecific binding was estimated in the presence of 10(-6) M naloxone. Separation of bound from free 3H-NAL was achieved by centrifugation at 20,000 X g. Concentration (fmol/mg original tissue wet wt) of 3H-NAL binding sites in POA tissue was higher (P less than .05) on d 28 postpartum in anestrous cows than in cyclic cows on d 42 + 56 postpartum (2.58 +/- .32 vs 1.58 +/- .10). When all anestrous cows were compared with cyclic cows, concentrations of 3H-NAL binding sites in POA tissues and in BF tissue were higher (P less than .05) in anestrous cows (anestrous POA, 2.12 +/- .17, cyclic POA, 1.58 +/- .10; anestrous BF, 2.94 +/- .41, cyclic BF, 2.19 +/- .16). Compared across brain regions for all cows, the concentration of specific binding sites for 3H-NAL was greater (P less than .01) in BF (2.5 +/- .2) than in POA (1.9 +/- .1) and greater (P less than .01) in POA than in HYP (1.5 +/- .1).(ABSTRACT TRUNCATED AT 250 WORDS)

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Relationship between pituitary GnRH-binding sites and pituitary release of gonadotrophins in post-partum beef cows

Cited by 15 publications

References 17 publications

Synchronisation of oestrus and reproductive performance of dairy cows following administration of oestradiol benzoate or gonadotrophin releasing hormone during a synchronised pro‐oestrus

Synchronisation of oestrus and reproductive performance of dairy cows following administration of oestradiol benzoate or gonadotrophin releasing hormone during a synchronised pro‐oestrus

Physiological mechanisms controlling anestrus and infertility in postpartum beef cattle.

Quantification of Naloxone Binding Sites in Brains from Suckled Beef Cows during Postpartum Anestrus and Resumption of Estrous Cycles

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