Abstract
Folliculogenesis and ovarian expression of mRNA encoding aromatase in anoestrous sheep after 5 days of glucose or glucosamine infusion or supplementary lupin feeding
Highlights
Nutrition is a major factor determining the ovulation rate in domestic animals (Lindsay et al, 1991) and the effect of nutrition is thought to be associated with alterations in the metabolic signals that mediate energy availability (Rhind and McNeilly, 1986; Rhind et al, 1989; Downing, 1994)
Ovulation rate is increased by the infusion of glucose into either the abomasum (Landau et al, 1995) or the jugular vein (Downing et al, 1995a), by the infusion of a mixture of branched chain amino acids into the jugular vein (Downing et al, 1995b) and by dietary supplementation with lupin grain (Nottle et al, 1988, 1990; Downing et al, 1995c)
The results of the present study show that the concentration of oestrogen in the ovarian vein draining an ovary containing an aromatase-positive follicle was significantly higher than the concentration of oestrogen in the ovarian vein draining an ovary containing only aromatase-negative follicles. These data are in agreement with other reports demonstrating that: (i) the largest follicle is the principal source of ovarian venous oestradiol (Baird and Scaramuzzi, 1976); (ii) aromatase activity of granulosa cells and oestradiol concentration in follicular fluid are positively correlated in follicles > 3.5 mm in diameter (Monniaux, 1987); and (iii) aromatase activity is found principally in the granulosa cells of peri-ovulatory follicles in superovulated sheep (Lautinick et al, 1994)
Summary
Nutrition is a major factor determining the ovulation rate in domestic animals (Lindsay et al, 1991) and the effect of nutrition is thought to be associated with alterations in the metabolic signals that mediate energy availability (Rhind and McNeilly, 1986; Rhind et al, 1989; Downing, 1994). Ovulation rate is increased by the infusion of glucose into either the abomasum (Landau et al, 1995) or the jugular vein (Downing et al, 1995a), by the infusion of a mixture of branched chain amino acids into the jugular vein (Downing et al, 1995b) and by dietary supplementation with lupin grain (Nottle et al, 1988, 1990; Downing et al, 1995c) All of these treatments increase peripheral insulin concentrations (Downing et al, 1995a,b,c), indicating that insulin-mediated glucose uptake, possibly by the ovary, modulates nutritional effects on ovulation rate. In support of this contention, the insulin-dependent glucose transporter
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
