Expression of a bovine growth hormone transgene inhibits pregnant mare's serum gonadotropin-induced follicle maturation in prepuberal gilts

Abstract

Prepuberal gilts were injected with PMSG to determine whether expression of a bovine growth hormone (bGH) transgene inhibited preovulatory maturation of ovarian follicles. Seven transgenic (TG) gilts of line 3706, which expresses a mouse metallothionein-bGH transgene, and eight nontransgenic, control (C) gilts (128 to 147 d old) were injected with PMSG, 12.5 IU/kg BW, 72 h before necropsy. Surface ovarian follicles > or = 1 mm in diameter were counted, measured for diameter, and aspirated for fluid. Follicles were classified morphologically as healthy or atretic and those with follicular fluid estradiol-17 beta > or = 100 ng/mL were classified as estrogenactive (EA). The number of follicles per gilt was 64.3 +/- 6.1 (mean +/- SEM) and did not differ significantly between bGH-TG and C gilts. The PMSG treatment induced growth of large (> 5 mm) follicles in both bGH-TG and C gilts. However, compared with C gilts, bGH-TG gilts had fewer (P < .05) large follicles (5.9 +/- 1.5 vs 18.3 +/- 5.4), a lower proportion of EA large follicles (35 +/- 12.5 vs 69 +/- 13.2%), and in large follicles less (P < .05) estradiol-17 beta (86 +/- 17 vs 350 +/- 69 ng/mL) and androstenedione (300 +/- 33 vs 1,283 +/- 221 ng/mL). Follicular fluid progesterone and inhibin did not differ significantly between bGH-TG and C gilts. The incidence of atresia among small and medium follicles did not differ significantly between bGH-TG and C gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration of porcine somatotropin by a sustained-release implant: effect on follicular growth, concentrations of steroids and insulin-like growth factor I, and insulin-like growth factor binding protein activity in follicular fluid of control, lean, and obese gilts

“…In comparison, Bryan et al (1989Bryan et al ( , 1992 found no effect of daily injections of pST on FFL estradiol concentrations in Yorkshire or Duroc gilts, whereas Spicer et al (1992) found that daily injections of pST had a significant inhibitory effect on FFL estradiol concentrations of obese gilts. Similar to gilts treated with daily pST injections, transgenic prepubertal gilts expressing the bST gene had significantly lower estradiol concentrations in FFL of large, but not medium, follicles than control gilts 3 d after PMSG treatment (Guthrie et al, 1993). The reasons for the discrepancies between the present and prior studies are unknown but may include differences in pSTand(or) IGF-I-mediated effects on granulosa cell cytodifferentiation (e.g., expression of gonadotropin receptors).…”

Protein (lysine) restriction in primiparous lactating sows: Effects on metabolic state, somatotropic axis, and reproductive performance after weaning1

“…Mullan et al (1991) reported a similar effect of feed restriction on FSH concentrations at the end of lactation and after weaning. Finally, high concentrations of GH may also have played a role in reduced ovulation rate, since overexpression of GH gene by transgenic prepuberal gilts reduces the number of large follicles and alters steroidogenesis (Guthrie et al, 1993). However, a stimulatory influence of exogenous GH on folliculogenesis also was reported in cyclic gilts (Kirkwood et al, 1988) and primiparous weaned sows (Whitley et al, 1998).…”

Influence de la nutrition sur le fonctionnement de l’axe gonadotrope

“…Des injections de GH ˆ des truies cycliques induisent une augmentation du taux dÕovulation chez les truies qui ovulent, mais aussi une augmentation du pourcentage de truies en anÏstrus (Kirkwood et al 1988b). Des truies prŽpub•res sŽcrŽtant de grandes quantitŽs de GH, ˆ la suite dÕun transfert de g•ne, prŽsentent un nombre rŽduit de grands follicules (Guthrie et al 1993). Par contre, des truies ayant un implant de GH pendant six semaines prŽsentent des concentrations plasmatiques et folliculaires dÕIGF-I et un nombre de follicules de taille moyenne ŽlevŽs par rapport aux truies tŽmoins (Echternkamp et al 1994).…”