A possible mechanism of the puberty-delaying effect of hippocampal lesions in female rats.

Untreated female Wister rats and females in which advancement of the onset of puberty was induced by bilateral lesioning of the medial preoptic area or the ventromedial-arcuate region, or by the daily s.c. injection of 0.05 microgram oestradiol benzoate/100 g b.w., were bilaterally lesioned in the anterior part of the ventral hippocampus at 21 days of age. Irrespective of the applied treatment, a significant delay of vaginal opening and of the first puberal ovulation resulted from the hippocampal lesions. This delay of the onset of puberty was consistently associated with a retardation of the body weight increase, so that the stage of body development necessary for the occurrence of spontaneous or precocious puberty was reached at later ages in these rats. The results suggest that a normal function of the hippocampus may be necessary for adequate somatic development during sexual maturation.