Effect of Ovariectomy and Estradiol on LH Patterns in Ewes

Diekman, M. A.; Malven, P.V.

doi:10.2527/jas1973.372562x

Cited by 51 publications

(39 citation statements)

References 7 publications

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“…As found by others (Butler, Malven, Willett & Bolt, 1972;Reeves, O'Donnell & Denorscia, 1972;Diekman & Malven, 1973), shortly after ovariectomy the control anoestrous ewes had plasma LH concentrations, pulse amplitudes and frequencies higher than those reported in entire anoestrous ewes (Martensz, Baird, Scaramuzzi & Van Look, 1976;Scaramuzzi & Baird, 1977). If the pulsatile release of LH reflects the pulsatile release of LH-RH (Lincoln & Short, 1980) Goodman & Legan, 1980), could in part reflect a reduction in hypothalamo-pituitary activity independent of the influence of ovarian hormones, as well as an increased inhibitory effect of oestrogen on LH release (Legan, Karsch & Foster, 1977).…”

Section: Discussionmentioning

confidence: 68%

Suppressed release of LH in ovariectomized post-partum ewes

Wright¹,

Stelmasiak²,

Anderson³

1983

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Summary. The patterns of LH release were studied in 5 ewes, ovariectomized when 3 days post partum, at 4, 14, 33, 47 and 61 days after ovariectomy. These patterns were compared with those in 4 seasonally anoestrous (control) ewes ovariectomized and sampled at the same times. In the control ewes regular pulsatile release of LH was apparent 4 days after ovariectomy: plasma LH concentrations and LH pulse frequencies, but not pulse amplitudes, then declined. In the post-partum ewes all indices of LH release were lower than those in the control ewes at 4 days after ovariectomy, but then they increased: pulse amplitude was greater (P < 0\m=.\05)at 14 days after ovariectomy, and plasma LH concentrations were greater (P < 0\m=.\05,0\m=.\01) at 14 and 33 days than in control ewes. These results indicate that the hypothalamo\p=n-\ pituitary axis of lactating ewes has a reduced capacity to release LH for only a short period after ovariectomy early in the post-partum period. This probably reflects the time needed for recovery from the inhibitory effects of ovarian and placental hormones, and may reflect reduced secretion of LH-RH.

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Section: Discussionmentioning

confidence: 68%

Suppressed release of LH in ovariectomized post-partum ewes

Wright¹,

Stelmasiak²,

Anderson³

1983

Reproduction

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“…It has long been known that LH concentrations increase after ovariectomy in the ewe (Arendarcik & Maracek, 1968;Roche, Foster, Karsch & Dziuk, 1970;Reeves, O'Donnell & Denorscia, 1972). However, data on the changes in pulsatile release of LH after ovariectomy are limited (Butler, Malvern, Willett & Bolt, 1972;Reeves et al, 1972;Diekman & Malvern, 1973;Wright, Stelmasiak & Anderson, 1983). The effects of season and time after ovariectomy require further investigation to assess the effects of steroid-dependent and -independent effects on changes in gonadotrophin secretion with season. In any long-term study of (Pelletier, Kann, Doláis & Rosselin, 1968), with the modifications recently described (Pelletier, Gamier, de Reviers, Terqui & Ortavant, 1982).…”

Section: Introductionmentioning

confidence: 99%

Changes in pulsatile LH secretion after ovariectomy in Ile-de-France ewes in two seasons

Montgomery¹,

Martin²,

Pelletier³

1985

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“…Both progesterone and oestradiol can inhibit the pulsatile release of LH (Diekman & Malven, 1973;Coppings & Malven, 1976;Hauger, Karsch & Foster, 1977), so that if the pulsatile release of LH reflects the pulsatile secretion of LH-RH (Lincoln & Short, 1981), pituitary LH depletion in pregnant and progesterone-oestrogen-treated ewes may be due to inadequate LH-RH action on the pituitary. In respect of prolactin, evidence from rats suggests that oestrogen acts at hypothalamic (Ratner & Meites, 1964;Fuxe, Hokfelt & Nilsson, 1969;Ramirez & McCann, 1964) and pituitary sites (Wolfe & Chadwick, 1936;Nicoli & Meites, 1964;Haug & Gautvik, 1976) (Chamley et al, 1974a;Chamley, Findlay, Jonas, Cumming & Goding, 1974b;Jenkin et al, 1977), there is only a parallel change in pituitary LH content (Chamley et al, 1976).…”

Section: Radioimmunoassaysmentioning

confidence: 99%