Undernutrition of ewe lambs in utero and in early post-natal life does not affect hypothalamic-pituitary function in adulthood.
The effect of undernutrition in utero, during late gestation (from day 100), and early neonatal life on hypothalamic-pituitary function was investigated in female lambs born to ewes fed rations calculated to provide either 100% (high; H) or 70% (low; L) of the energy requirements to sustain a twin pregnancy. Following parturition in early spring, ewes and lambs were maintained on pasture with sward heights of 6 cm (H) or 4 cm (L) until week 8 of lactation and then sward heights of 5 cm (H) or 3 cm (L) until weaning at week 14. Mean lamb birth weights were 18% lower in L than H animals (P<0.05) and mean liveweights were 23% lower in the L animals (P<0.001) at weaning at 14 weeks of age. Liveweight differences were not significant at, or after, 26 weeks of age. There were no significant differences between pre-pubertal H and L animals, either before (26 weeks) or after ovariectomy (31 weeks), with respect to hypothalamic or pituitary activity, as measured by LH pulse frequency, pulse amplitude or mean plasma LH and FSH concentrations and the responses to GnRH injection as measured by LH peak amplitude, respectively. Similarly there were no differences in any of these variables in pubertal animals at 18 months of age. At 31 weeks of age, H animals had significantly lower pituitary GnRH receptor binding (P<0.01) and lower ERalpha mRNA content (P<0.05) than L lambs. There were no differences with treatment in the abundance of mRNA for LHbeta, FSHbeta or GnRH-receptor at 31 weeks of age or in pubertal animals aged 18 months, when there were no significant differences with treatment in GnRH receptor binding or ERalpha mRNA expression. It is concluded that effects on lifetime reproductive function of female sheep of undernutrition during late gestation and early neonatal life are unlikely to be expressed through permanent changes in hypothalamic-pituitary function and are therefore attributable to effects exerted directly on the ovary.
Borwick
S C
SC
Macaulay Institute, Craigiebuckler, Aberdeen, Scotland AB15 8QH, UK.
Rae
M T
MT
Brooks
J
J
McNeilly
A S
AS
Racey
P A
PA
Rhind
S M
SM
D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D002149:Energy Intake; D047628:Estrogen Receptor alpha; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics; D005865:Gestational Age; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage; D007031:Hypothalamus / Q000503:physiopathology*; D007774:Lactation; D007986:Luteinizing Hormone / Q000032:analysis / Q000097:blood; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics; D009748:Nutrition Disorders / Q000150:complications* / Q000503:physiopathology; D010902:Pituitary Gland / Q000737:chemistry / Q000503:physiopathology*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology; D011297:Prenatal Exposure Delayed Effects; D012333:RNA, Messenger / Q000032:analysis; D011960:Receptors, Estrogen / Q000235:genetics; D011966:Receptors, LHRH / Q000235:genetics / Q000378:metabolism; D012756:Sheep / Q000196:embryology*; D014886:Weaning
D047628:Estrogen Receptor alpha; D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone