A. Abizaid et al., CHANGES IN NEUROPEPTIDE-Y IMMUNOREACTIVITY IN THE ARCUATE NUCLEUS DURING AND AFTER FOOD RESTRICTION IN LACTATING RATS, Brain research, 761(2), 1997, pp. 306-312
Previous studies have demonstrated that food restriction during lactat
ion extends the length of lactational infertility in rats. In order to
determine whether Neuropeptide Y (NPY) plays a role in the increased
length of lactational infertility seen in food-restricted rats, NPY im
munoreactivity in the arcuate nucleus of lactating rats that were ad l
ib fed or food restricted from Day 8 to 14 postpartum was compared. Fo
od-restricted rats showed higher numbers of NPY-stained cells at the e
nd of the food-restriction period (Day 15 postpartum) than did ad lib-
fed rats at the same stage of lactation. This difference persisted unt
il Day 25 postpartum although all animals were fed ad libitum from Day
15 onwards. Switching litters between ad lib-fed and food-restricted
females from Day 15 until Day 20 postpartum did not eliminate the diff
erence in NPY immunoreactivity between the two diet conditions. Given
that food restriction during lactation leads to a prolonged suppressio
n of LH release that also persists after refeeding and is not affected
by the nutritional status of the litter, these data are consistent wi
th a role for NPY in the prolonged suppression of reproductive functio
n seen in food restricted lactating rats.