Biomedical subjects

A L Favaretto

Publications and source records attributed to A L Favaretto.

49 records · Page 3Linked to original sources

PubMed1989

[Characterization of a chondrocyte primary culture from rib cartilage of the rat].

In order to standardize and to characterize a chondrocyte primary culture, cells from rat rib resting cartilage were used. High yield (0.99 +/- 0.18 x 10(6) cells/rat) and viability (91.76%) of costal cartilage cells was reached by enzymatic digestion with collagenase. The cells were cultivated in Dulbecco's medium (DME) supplemented with 10%. Heat inactivated newborn calf serum, at 37 degrees under humidified atmosphere of 5% CO2 in air. Two or three days after plating, the cells were attached to the surface of tissue culture weel, and began dividing. Adhesion was independent of plating density. The doubling time of cell population was found to be 23.19 hours. The cells became a monolayer and required easy maintenance. The results support the contention that rat costal cartilage is a good source of chondrocytes for primary culture cells experiments.

Animals↗

PubMed1989

Modulatory effects of adrenergic agonists on testosterone secretion from rat dispersed testicular cells or Percoll-purified Leydig cells.

1. Freshly dispersed testicular interstitial cells as well as Percoll-purified Leydig cells were studied in vitro in order to evaluate the effect of adrenergic agonists on testosterone (T) secretion. 2. Epinephrine and phenylephrine did not change the rate of T release under basal conditions in freshly dispersed interstitial cells, but enhanced it during human chorionic gonadotropin (hCG) stimulation. Norepinephrine and clonidine had no effect on T secretion. 3. In contrast, in Percoll-purified Leydig cells epinephrine increased T release both under basal and hCG-stimulated conditions. 4. These data demonstrate that neurotransmitters may participate in T secretion from isolated Leydig cells.

Animals↗

PubMed1988

Characterization of adrenergic control of the Leydig cell steroidogenesis: identification of both stimulatory and inhibitory components.

Percoll-purified Leydig cells were studied in vitro in order to evaluate the effect of adrenaline on testosterone (T) secretion. Adrenaline enhanced the basal and potentiated the hCG-induced T release. A similar effect was also obtained with the beta 2-agonist, salbutamol. Although phenylephrine, an alpha 1-agonist, did not alter the basal T secretion, it enhanced hCG-mediated T secretion. Para-aminoclonidine, an alpha 2-agonist, decreased the basal T release without altering the hCG-stimulated T release. These data demonstrate that either inhibitory or stimulatory effects on T release can be obtained and that they depend on the adrenoreceptor subtype involved.

Animals↗

PubMed1988

Influence of age on the production of rat spermatozoa, on their concentration in the cauda epididymidis, and on FSH, LH and testosterone plasma levels.

Testis samples were taken from young (3 months), middle-aged (12 months) and aged (24 months) male rats, processed, stained and examined via a light microscope. There were no prominent abnormal germinal epithelium and interstitial tissue. However, the aging process promoted a significant decrease in the mean amount of spermatids 19 per cross tubular section, and in the amount of Sertoli cells per cross tubular section in 24-month-old rats. The concentration of spermatozoa in the cauda epididymidis showed a gradual decrease from 3 to 12 and 24 months. After hCG injection all groups of animals exhibited an increase in plasma testosterone level, although the response was smaller in 12- and 24-month animals compared to the young mature (3 months) ones.

Aging↗

PubMed1988

Functional disturbance of rat sexual accessory glands in an early phase of lead intoxication.

In order to investigate the effects of chronic lead intoxication on sexual accessory glands adult male Wistar rats were poisoned by ad libitum ingestion of lead acetate at concentrations of 0.5 g/l and 1.0 g/l for 90 d. Blood lead exhibited a significant increase in both treated groups. A decrease in hematocrit and hemoglobin, besides a rise in glycemic levels, confirmed lead intoxication. No sign of lesion was detected upon histologic examination of prostate, seminal vesicle, and coagulating gland. A morphometric technique revealed that, in this early phase of intoxication, no alteration occurred in the prostate's and seminal vesicle's epithelial height. However, a significant decrease in fructose content was observed in both lead treated groups. The results, revealing a precocious envolvement of male sexual accessory glands in lead intoxication, were related to disturbance in plasma testosterone level and also probably in androgen receptors.

Animals↗

PubMed1987

Leydig cell hypertrophy and hyperplasia in adult rats treated with an excess of human chorionic gonadotrophin (hCG).

A morphometric study was undertaken to determine to what extent the increase in LEYDIG cell activity is related to an increase in their number and/or size. An attempt was also made to consider the morphological characteristics of the cells in terms of their probable functional capacity. Following 8 h to 3 d of excess hCG treatment, LEYDIG cells nuclear volume exhibited an increase of 16 to 18% while no significant increase in cells number was observed. By 7 d of hCG treatment, the nuclear hypertrophy (42%) coexisted with hyperplasia (33%). After 14 d of stimulation, a 41% augment in cells number and 31% increase in nuclear volumes were found. Such morphometric parameters were correlated with plasma levels of testosterone. The results suggest that hypertrophy plays a more important role in the enhancement of LEYDIG cells secretory activity in the initial phase of hCG stimulation. A subsequent hyperplasia seems to become relatively more important in longer periods of treatment. Our findings support the statement that both hCG dose and time of treatment, and consequently the plasma level of testosterone, are important parameters to be considered when the functional activity of LEYDIG cells is been evaluated by morphometric techniques.

Animals↗

PubMed1986

Effect of spermatic cord phenolization on the spermatogenetic and secretory activities of adult rat testes.

We evaluated the effect of testicular denervation on the spermatogenetic and secretory activities of the adult rat testis. Testes were denervated by applying 20% (v/v) phenol to the spermatic cord and measurements were made 30 days thereafter. There was an increase in the frequency of stages VII-VIII of the seminiferous epithelium cycle, indicating an increase in the relative amount of mature elongated spermatids present in the seminiferous tubules. The frequency of stage XIV remained unchanged, suggesting that the rate of reductional divisions was constant. A decrease in the nuclear volume of Leydig cells paralleled increased plasma LH and testosterone levels. The results are discussed in terms of a possible role of phenol-sensitive neural elements which affect testicular spermatogenetic and secretory functions.

Animals↗

PubMed1985

Regulation of gonadotrophin function in hemidecorticate rats.

The present review focuses on some aspects of the regulation of gonadotrophin (LH and FSH) and prolactin secretion in rats submitted to hemidecortication (HD). The removal of rhinencephalic and cortical structures induces the following changes: Irregular and erratic estrous cycle; Increase in LH and FSH secretion in the afternoon of proestrus and after uni- or bilateral castration; When hormonal replacement therapy was administered to castrated female rats, the controls needed larger doses of estradiol benzoate (E2) to reduce LH levels than the HD animals, which suggests an increase in the sensitivity of the hypothalamus-hypophysis axis to gonadal steroid negative feedback. When HD was performed during the neonatal period (1-3 days old), an earlier onset of puberty and sexual maturation was observed in both female and male HD rats than in controls. During the puberal evolution the HD male rats showed elevation in plasma testosterone levels, an increase in the testicular response to hCG and also in the number of testicular binding sites to LH and FSH at 38-43 days (before the onset of puberty) and to prolactin (after 60 days). The results suggest that after removal of cortical and subcortical structures (HD), with predominant inhibitory influences, the hypothalamus-hypophysis becomes more sensitive to the LH and FSH releasing mechanisms.

Age Factors↗

PubMed1985

Evaluation of the frequency of stages VII-VIII and XIV of the tubular cycle of adult rats, 30 d after phenolization of the spermatic cord. Response to chronic administration of hCG.

A study was carried out to evaluate the effect of testicular denervation on the spermatogenetic activity of the testes and on the ability of the germinal epithelium to respond to chronic administration of hCG. Testes of adult rats were denervated by phenolization of the spermatic cord. An increase in the frequency of stages VII-VIII of the tubular cycle was observed 30 d later in phenolized rats treated with hCG, demonstrating an increase in the amount of spermatozoa present in the seminiferous tubules of these animals. The frequency of stage XIV remained unchanged after phenolization of the spermatic cord and/or chronic treatment with hCG, indicating that the rate of reductional divisions remained constant. The results suggest the autonomic nervous system may have some functional significance by participating in a neuroendocrine mechanism and consequently in the spermatogenesis.

Animals↗

PubMed1984

Histophysiological study of vasectomized rats.

An histophysiological evaluation was performed of adult rat testes 30 days after vasectomy. A higher frequency of stage VII-VIII of the tubular cycle was observed, indicating sperm accumulation. Seminiferous tubules and tubular lumen having increased diameters were also observed, but these results cannot be explained only in terms of increase in retrograde intratubular pressure. The rise in basal gonadotrophin levels as well as in testosterone levels observed under basal conditions and 30 and 60 min after stimulation with human chorionic gonadotrophin (hCG) suggested hyperactivity of the Leydig cells. The observed increased frequency of Leydig cells with smaller nuclear volumes may be correlated with higher luteinizing hormone levels. The results are discussed in terms of the possible role of neuromotor components resected during vasectomy, which may alter the spermatogenic and the secretory functions of the testis.

Animals↗

PubMedDate not supplied

Time-dependent effects of lead on rat reproductive functions.

The effects of exposure to lead on endocrine function and the reproductive parameters were studied in pubertal rats treated with 1.0 g l-1 lead acetate in drinking water for 20 days (subacute group) or 9 months (chronic group) in addition to i.v. injections of lead acetate (0.1 mg 100 g-1 body wt.) every 10 (subacute group) or 15 days (chronic group). Although basal levels of testosterone were higher both in plasma and in testes of acutely intoxicated animals, the circulating levels of luteinizing hormone (LH) were not affected in either group, nor was the LH-releasing hormone content of the median eminence. The density of [125I]LH/human chorionic gonadotrophin (hCG) binding sites in testicular homogenates was reduced by saturnism in both groups, concomitant with a significantly increased apparent affinity constant of the hormone-receptor complex. These data can be viewed as the result of a mixture of specific lead toxicity (e.g. at the enzyme level) with other more general actions (e.g. at the level of the hypothalamus-pituitary-testicular axis).

Animals↗

PubMedDate not supplied

The hypophyseal-testicular axis and sex accessory glands following chemical sympathectomy with guanethidine of pre-pubertal to mature rats.

Selective chemical sympathectomy of the internal sex organs of prepubertal to mature male Wistar rats was performed by chronic treatment with low doses of guanethidine. Plasma testosterone and luteinizing hormone and the intratesticular level of testosterone were determined. The weight and fructose content of seminal vesicle and ventral prostate were also investigated. The results showed that sympathetic innervation is related to the control of the hypophyseal-testicular axis as well as to the growth and potential secretory activity of the male sex accessory glands.

Animals↗

PubMedDate not supplied

Inhibitory role of cholinergic agonists on testosterone secretion by purified rat Leydig cells.

The effects of cholinometics on basal or hCG-induced testosterone (T) release by Percoll-purified Leydig cells of the rat were studied. Acetylcholine and carbachol as well as nicotine decreased basal and hCG-induced T secretion. The ganglionic nicotine antagonist hexamethonium promoted a partial reversal of the inhibitory effect of nicotine on basal or hCG-stimulated T secretion. Atropine also reduced the inhibitory effect of carbachol on basal or stimulated androgen release. These data indicate that, in short-term incubations, testosterone released by purified Leydig cells is inhibited by nicotinic and muscarinic cholinergic agonists, thus supporting the hypothesis that parasympathetic autonomic system may be involved in the negative regulation of testicular androgen secretion.

Animals↗