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| Rearing rats in small litters leads to obesity and reproductive dysfunction. We investigated the effects of rearing female rats in small litters on various reproductive parameters during puberty and into adulthood, and the possible involvement of local ovarian sympathetic nervous activity. The litter size was adjusted on postnatal day one to four pups for the small litter and 12 pups per dam for the normal litter. Vaginal opening was recorded, and oestrous cyclicity was monitored daily immediately post puberty for 14 days and again at 8-9 weeks of age. At the time of puberty and 10 weeks of age, the ovaries were collected. The thickness of the theca interna of the largest antral follicles was measured. Ovarian sympathetic nerve activity was assessed immunohistochemically by measuring levels of ovarian nerve growth factor receptor (p75NGFR) and tyrosine hydroxylase (TH). In rats reared in small litters, there was a significant advancement of puberty and disruption of oestrous cyclicity immediately post puberty. The thickness of the theca interna increased and the expression profiles of ovarian p75NGFR and TH increased in small litter rats at puberty, but this did not persist into adulthood. These data suggest that rearing rats in small litters leads to irregular reproductive cycles, which might involve increased local ovarian sympathetic nerve activity. |
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| Keywords:ovary, obesity, puberty, follicle, reproduction, sympathetic. |
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