Effects of sympathetic denervation on follicular distribution, oestradiol and progesterone serum levels in prepubertal hemi-ovariectomized female guinea pig.

Hemi-gonadectomy performed in prepubertal female guinea pigs is followed by a compensatory ovarian hypertrophy (COH) and compensatory ovulation (CO). Sympathetic denervation diminished the COH (left ovary: 28 +/- 1.6% versus 46 +/- 4% (control), P < 0.05; and right ovary: 21.3 +/- 3.2% versus 34.2 +/- 3.7% (control), P < 0.01) and does not modify the CO. The mean follicular diameter increased only in the right ovary of hemi-gonadectomized animals. This increase is greater in the hemi-gonadectomized-denervated groups. The mean follicular diameter measured in the right and left ovaries showed an opposite response in hemi-ovariectomized and hemi-ovariectomized-denervated animals: the diameter increased in the right ovary without modifications in the left. Present results add further support to the participation of ovarian innervation on the mechanisms, which regulate follicular development.

Effects of guanethidine administration on compensatory ovarian hypertrophy, compensatory ovulation and follicular development in the prepubertal female guinea pig.

We analyzed the participation of sympathetic ovarian innervation in the prepubertal female guinea pig on regulation of compensatory ovarian hypertrophy (COH) and compensatory ovulation at puberty. The COH of the left ovary was significantly higher that of the right one (left ovary: 41.5+/-5.2 vs. 27.5+/-5.6%, p<0.05, Kruskal-Wallis test). The sympathetic denervation induced by guanethidine administration beginnings at birth or on day 10 resulted in a significant increase of the COH by each ovary (p<0.05, Kruskal-Wallis test). Only one of the six untreated control guinea pigs sacrificed at the follicular phase ovulate. All the hemiovariectomized animals with the left ovary in situ ovulated, while only two out of five with the right ovary in situ did (100 vs. 40%: p<0.001, Kruskal-Wallis test), unlike the denervated animals, which did not ovulate. The number of corpora lutea present in the ovaries was similar among all groups of animals. These results demonstrate differences in the follicular diameter in untreated female guinea pigs and add further support to the concept of asymmetrical response of the ovaries to denervation.

Effects of functional peripheral sympathetic denervation induced by guanethidine on follicular development and ovulation of the adult female guinea pig.

The present study investigates the effects of functional sympathetic peripheral denervation induced by guanethidine sulphate (GTD) to adult female guinea pigs in the follicular (FPh) or luteal phases (LPh) on their oestrous cyclicity and ovulation. No differences were observed in oestrous cyclicity or the average number of corpora lutea present in the ovaries between the control and denervated animals. Guanethidine sulphate administration resulted in a significant decrease in ovarian norepinephrine content, higher for the left ovary than for the right one. Serum oestrogen and progesterone concentrations, the mean of follicles, and its diameter were different, depending on the oestral cycle in which the treatment was performed. These results suggest that in adult normal female guinea pigs, ovarian innervation participates in the regulation of follicular development in an inhibitory way.

Effects of peripheral sympathetic denervation induced by guanethidine administration on the mechanisms regulating puberty in the female guinea pig.

The effects of peripheral sympathetic denervation induced by guanethidine administration to newborn and 10-day-old female guinea pigs on puberty, ovulation and the follicular population were analysed. Peripheral sympathetic denervation beginning at birth resulted in the loss of ovarian norepinephrine content (0.95. +/- 0.1 ng/mg wet tissue in untreated control animals vs non detectable in treated animals). Guanethidine administration to newborn or 10-day-old guinea pigs advanced puberty (age of vaginal opening: 27 +/- 1.2 days (newborn), 26 +/- 1.7 (10-day-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/100 g body weight) of the ovaries and adrenals in the denervated animals autopsied during the late follicular phase (24-48 h after vaginal opening) increased (ovaries: 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 animals 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 in the ovaries of denervated animals was significantly higher than in control animals (1736 +/- 230 vs 969 +/- 147, P < 0.05). The mean diameter of the follicles in the untouched control ovary in animals killed in the late follicular phase was significantly larger than from animals killed in the late luteal phase (263 +/- 3.9 microns vs 248 +/- 3.0 microns, P < 0.01). The mean diameter of the follicles measured in the ovaries of denervated animals was significantly higher than in controls (animals treated from birth 274 +/- 2.0 microns vs 255 +/- 2.4, P < 0.05; animals treated from day 10, 286 +/- 2.3 microns vs 257 +/- 2.3, P < 0.05). When the mean diameter of the follicles in the left and right ovary of the untouched control was analysed, the follicular diameter in the left ovary was significantly larger than in the right ovary (309 +/- 6.0 microns vs 214 +/- 3.9, P < 0.01); the response of the left and right ovaries to sympathetic denervation was the opposite. The results obtained 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 other regulatory mechanisms.

A fast staining method for CNS slices.

We describe a staining technique for quick observation of the microanatomy of the vertebrate CNS. Successive soaking of the sections in tannic acid and ferric chloride produces a black colour in the gray matter. The procedure takes 5 min and is useful for identifying electrode penetrations, localization of lesions or teaching neuroanatomy.

Ouabain uptake by endocytosis in isolated guinea pig atria.

Mammalian cells specifically internalize some molecular species through receptor-mediated endocytosis (RME). We have used four different experimental protocols to investigate whether ouabain enters cardiac cells of guinea pig atrium through this pathway. First, by electron microscope morphometry we found that ouabain increased endocytic vesicles in atrial cells. Second, by scintillation counting we found that [3H]ouabain uptake by the tissue is decreased by three treatments that decrease RME, i.e., NH4Cl, trifluoperazine, and 16 mM [K+]0. Third, by radioautography at the electron microscope level, we checked that in preceding experiments [3H]ouabain was washed out of plasma membrane after 60-min rinse and interiorized into the cardiac cells. Fourth, isometric tension recordings showed that the positive inotropic effect of ouabain was diminished in the presence of inhibitors, whereas that of a hydrophobic analogue, ouabagenin, was not affected. These results suggest that ouabain enters cardiac cells through RME and also that an intracellular site may, at least in part, be responsible for its inotropic effect.