EFFECTS OF PERIPHERAL SYMPATHETIC DENERVATION INDUCED BY GUANETHIDINEADMINISTRATION ON THE MECHANISMS REGULATING PUBERTY IN THE FEMALE GUINEA-PIG

The effects of peripheral sympathetic denervation induced by guanethid ine administration to newborn and 10-day-old female guinea pigs on pub erty, ovulation and the follicular population were analysed. Periphera l sympathetic denervation beginning at birth resulted in the loss of o varian norepinephrine content (0.95. +/- 0.1 ng/mg wet tissue in untre ated control animals vs non detectable in treated animals). Guanethidi ne administration to newborn or 10-day-old guinea pigs advanced pubert y (age of vaginal opening: 27 +/- 1.2 days (newborn), 26 +/- 1.7 (10-d ay-old) vs 37 +/- 0.7 (control), P < 0.001) and ovulation. The number of corpora lutea in control and denervated animals was similar (3.5 +/ - 0.2 vs 3.3 +/- 0.3). The relative weight (mg/100g body weight) of th e ovaries and adrenals in the denervated animals autopsied during the late follicular phase (24-48 h after vaginal opening) increased (ovari es: 27.8 +/- 1.3, 28.9 +/- 3.0 vs 20.9 +/- 0.8: P < 0.05; adrenals 36. 4 +/- 1.4, 37.0 +/- 0.8 vs 31.6 +/- 1.5, P < 0.05), while the uterine weight diminished (179 +/- 13: 149 +/- 28 vs 292 +/- 20). When the ani mals were killed during the late luteal phase (9-11 days after vaginal closure), the relative weight of the ovaries of newborn guanethidine- treated animals was higher than that of the control animals (21.4 +/- 1.7 vs 16.8 +/- 1.4, P < 0.05). The mean number of follicles counted i n the ovaries of denervated animals was significantly higher than in c ontrol animals (1736 +/- 230 vs 969 +/- 147, P < 0.05). The mean diame ter of the follicles in the untouched control ovary in animals killed in the late follicular phase was significantly larger than from animal s killed in the late luteal phase (263 +/- 3.9 mu m vs 248 +/- 3.0 mu m, P < 0.01). The mean diameter of the follicles measured in the ovari es of denervated animals was significantly higher than in controls (an imals treated from birth 274 +/- 2.0 mu m vs 255 +/- 2.4, P < 0.05; an imals treated from day 10, 286 +/- 2.3 mu m vs 257 +/- 2.3, P < 0.05). When the mean diameter of the follicles in the left and right ovary o f the untouched control was analysed, tile follicular diameter in the left ovary was significantly larger than in the right ovary (309 +/- 6 .0 mu m vs 214 +/- 3.9, P < 0.01); the response of the left and right ovaries to sympathetic denervation was the opposite. The results obtai ned in the present study suggest that ovarian innervation plays a role in the regulation of follicular growth, maturation and atresia which is not related to changes in steroid secretion by the ovary, but to ot her regulatory mechanisms.