Biomedical subjects

T L Lamano-Carvalho

Publications and source records attributed to T L Lamano-Carvalho.

At least 19 recordsLinked to original sources

PubMed2000

Antireproductive effect of the calcium channel blocker amlodipine in male rats.

The purpose of the present study was to investigate whether treatment of male rats with the calcium antagonist amlodipine, used in the treatment of hypertension and angina, interferes with the reproductive function of male rats. Amlodipine treatment (0.04 mg amlodipine besylate/rat/day for 30 days) decreased plasma follicle-stimulating hormone and testosterone but not luteinizing hormone or prolactin concentrations (measured by double-antibody radioimmuno-assay). A significant reduction (23%) was observed in sperm density (sperm suspension collected from the cauda epididymidis) as well as in the amount of mature spermatids (14%) and Sertoli cells (9%) counted in seminiferous tubule cross-sections (400 x magnification). The results reveal the deleterious effects of subacute amlodipine treatment on the reproductive function of male rats.

Amlodipine↗

PubMed1998

Decreased spermatogenic and androgenic testicular functions in adult rats submitted to immobilization-induced stress from prepuberty.

We investigated whether chronic stress applied from prepuberty to full sexual maturity interferes with spermatogenic and androgenic testicular functions. Male Wistar rats (40 days old) were immobilized 6 h a day for 60 days. Following immobilization, plasma concentrations of corticosterone and prolactin increased 135% and 48%, respectively, while plasma luteinizing hormone and testosterone presented a significant decrease of 29% and 37%, respectively. Plasma concentration of follicle-stimulating hormone was not altered in stressed rats. Chronic stress reduced the amount of mature spermatids in the testis by 16% and the spermatozoon concentration in the cauda epididymidis by 32%. A 17% reduction in weight and a 42% decrease in DNA content were observed in the seminal vesicle of immobilized rats but not in its fructose content. The growth and secretory activity of the ventral prostate were not altered by chronic stress.

Androgens↗

PubMed1996

Sexual development of hypernatriophilic male rats up to puberty.

The sexual development of normonatriophilic (Normo) and hypernatriophilic (Hyper) male Wistar rats was compared from 30 to 60 days of age (N = 8-10 per group) with emphasis on the onset of puberty. Hyper rats (more than 5 ml of saline a day in a situation of free access to tap water and 1.5% NaCl) had a 20-39% body weight reduction and a 22-29% testicular growth rate decrease compared to Normo rats. Plasma testosterone (ng/ml) of Normo rats increased from 0.29 +/- 0.02 at 30 days to 1.42 +/- 0.18 at 50 days, decreasing to 0.87 +/- 0.15 at 60 days of age, with no significant difference compared to Hyper animals. Plasma concentration (ng/ml) of luteinizing hormone (LH) was significantly lower in Hyper (0.21 +/- 0.03) than in Normo (0.43 +/- 0.06) rats at 40 days. At 30 days, plasma follicle stimulating hormone (FSH) levels (ng/ml) were significantly higher in Hyper (18.9 +/- 1.3) than in Normo (15.6 +/- 0.5) rats. It is possible that increased levels of FSH compensated for a reduced amount of LH, thus allowing similar testosterone production by Hyper and Normo rats. At 30 days, testis maturation was higher in Hyper rats, as indicated by a 22% increase in tubular cross-sections with young spermatids. At 50 days, spermatogenesis progressed to the production of mature spermatids (onset of puberty) and Hyper rats exhibited an 18.7% lower rate of testis maturation. Testis maturation was similar in Hyper and Normo rats at 60 days.

Animals↗

PubMed1995

Chemical sympathectomy blocks androgen biosynthesis during prepuberty.

Twenty-one-day old male Wistar rats were injected subcutaneously with guanethidine (GUA) at doses of 5 and 10 mg kg-1 day-1 for 20 days. Animals were sacrificed by decapitation during the prepubertal (41 days of age) and early-pubertal (51 days of age) periods of sexual development. The testes were collected, frozen in liquid N2 and stored at -70 degrees C until determination of testicular progesterone (P), androstenedione (A) and testosterone (T). Higher levels of P (2.18 +/- 0.24 ng/g, control = 1.24 +/- 0.16 ng/g) associated with decreased levels of androgens (A = 0.26 +/- 0.06 ng/g and T = 2.05 +/- 0.19 ng/g; control = 1.86 +/- 0.76 ng/g and 8.48 +/- 1.16 ng/g, respectively) were observed in 10 mg GUA-treated rats of prepubertal age, while only P levels (3.12 +/- 0.51 ng/g, control = 1.73 +/- 0.27 ng/g) were increased in rats of early pubertal age. It is important to note that in 41-day old male rats both 5 and 10 mg were effective in decreasing testicular concentration of testosterone. These results suggest that the sympathetic innervation of the testis is involved in the modulation of androgen biosynthesis, acting through a selective step in the steroid biochemical pathway during the pubertal process and that under the conditions employed the blockage in androgen biosynthesis in the prepubertal stage of sexual maturation in dependent on the dose of GUA.

Androgens↗

PubMed1994

Sexual development of male Wistar rats.

1. Sexual development was investigated in male Wistar rats from 22 to 97 days of age by morphometric, biochemical and radioimmunological methods. 2. The first significant increase of plasma testosterone (T) occurred from 40 to 50 days of age and a progressive enhancement was observed thereafter to a maximum at 76 days (5.4 +/- 0.9 ng/ml). From that time onward, plasma T was gradually depressed to adult levels at 97 days of age (2.0 +/- 0.3 ng/ml). Plasma prolactin increased in parallel to T, reaching a maximum at 76 days (9.2 +/- 0.9 ng/ml) and attaining a lower plateau by 83 to 97 days of age (5.0 +/- 0.5 ng/ml). A small but significant increase was observed in plasma luteinizing hormone from 22 to 83 days of age. Plasma follicle stimulating hormone was high at 22 days, increased to a maximum at 40 days (15.4 +/- 0.6 ng/ml) and fell slowly to a lower plateau by 76 to 97 days of age. 3. Fructose content in the ventral prostate increased abruptly from 50 to 63 days of age (148.8 +/- 19.8 micrograms) and no significant change was observed thereafter. A progressive increase in the seminal vesicle fructose content was observed from 40 to 63 days (45.6 +/- 2.8 micrograms) when a plateau was reached. 4. The evolution of the germinal epithelium was investigated in cross-sections of seminiferous tubules analyzed at random for the presence of the most advanced germ cell and also for sperm production (estimated by the number of spermatids in stages 15 to 18 of spermiogenesis).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1993

Prepubertal development of rat prostate and seminal vesicle following chemical sympathectomy with guanethidine.

1. The internal genital organs of prepubertal, 21-day old male Wistar rats were sympathectomized by ip injection of guanethidine (G), at doses of 5 mg/kg per day (N = 10) or 10 mg/kg per day (N = 10), for 20 days. Controls (N = 10) received saline. 2. Plasma testosterone level (measured by radioimmunoassay) decreased significantly in sympathectomized rats from 4.11 +/- 0.57 to 1.76 +/- 0.37 ng/ml (5 mg/kg G) and to 1.17 +/- 0.26 ng/ml (10 mg/kg G). Plasma levels of luteinizing and follicle-stimulating hormones and of prolactin were unaltered. 3. Chemical denervation caused a significant decrease in ventral prostate wet weight from 74.3 +/- 5.5 to 59.3 +/- 4.7 mg (5 mg/kg G) and to 54.6 +/- 4.1 mg (10 mg/kg G) and in seminal vesicle wet weight from 36.5 +/- 6.8 to 31.7 +/- 5.2 mg (5 mg/kg G) and to 21.3 +/- 1.6 mg (10 mg/kg G). 4. The potential secretory activity of the prostate (measured in terms of fructose content) decreased significantly in guanethidine-treated rats from 0.38 +/- 0.02 to 0.30 +/- 0.02 mg/g (5 mg/kg G) and to 0.20 +/- 0.02 mg/g (10 mg/kg G). The seminal vesicle fructose content (0.33 +/- 0.04 mg/g for controls), however, was not altered by chemical denervation. 5. Our data suggested that sympathetic neurons may be involved in the control of LH receptors, at least in the prepubertal phase of sexual development. They may also be directly related to growth and secretory activity of the male accessory sex glands.

Animals↗

PubMed1991

Effect of an LH-RH analog on cat testis and adrenal cortex function.

The LH-RH analog LH-RH-A (des-Gly10,[D-Trp6]-LH-RH ethylamide) was administered in pharmacological doses (20 micrograms/kg, sc) to adult male cats for 15 days and its effect on testis and adrenal function was determined. Daily administration of the analog promoted a 3-fold increase in plasma testosterone levels after 7 days, indicating a stimulatory effect of LH-RH-A (mean +/- SD for 6 treated cats, 1.88 +/- 0.35 vs 0.51 +/- 0.08 ng/ml for 6 control cats). After 15 days the LH-RH-A-treated group exhibited a similar plasma testosterone concentration as the control group (mean +/- SD, 0.96 +/- 0.35 ng/ml vs 0.88 +/- 0.39 ng/ml, respectively), similar testicular and adrenal weights and no significant differences in the spermatogenic process. However, semiquantitative analysis of the zona fasciculata of the adrenals from the LH-RH-A-treated group showed a significant accumulation of a substance not stained by hematoxylin-eosin or Schiff periodic acid (mean +/- SD of index of accumulation was 3.50 +/- 0.4 for treated cats vs 2.20 +/- 0.3 for control cats). The present results show that pharmacological doses of LH-RH-A have an effect on the adrenal cortex of cats without modifying spermatogenesis or plasma testosterone levels.

Adrenal Cortex↗

PubMed1991

Effect of low-intensity pulsed ultrasound on prepubertal rat testis.

The testes of prepubertal male rats (N = 12) aged 21 days were stimulated with low-intensity pulsed ultrasound (1.5-MHz frequency, 1-KHz repetition pulse rate, 200-microseconds pulse width, 30-V peak-to-peak amplitude and 20-mW/cm2 intensity) applied to the skin for 20 min/day for 7 days. Control rats (N = 8) were manipulated in the same manner but not submitted to ultrasound. Ultrasound stimulation promoted a significant increase in plasma testosterone (62%) leading to a significant increase in seminal vesicle relative weight (35%) as well as an increase in the fructose (92%) and DNA (200%) contents of the gland. No differences were detected between ultrasound-treated and control animals in terms of body weight and the relative weights of testis, cauda epididymidis, testis DNA and mitosis.

Animals↗

PubMed1990

Spermatogenic and steroidogenic testicular function in hypothyroid pubertal rats.

The reproductive system of immature rats is held to be more influenced by thyroid dysfunction than that of adult animals. The effect of hypothyroidism on the spermatogenic process of the rat has not been reported previously. The objective of the present study was to investigate the spermatogenic and steroidogenic functions of pubertal hypothyroid rats. Hypothyroidism was induced by ad libitum ingestion of a 0.05% solution of propylthiouracil for 60 days, and confirmed by reduced plasma thyroxine levels in treated rats. Plasma testosterone level, the histological features of the testis and cauda epididymis and the concentration of spermatozoa stored in the cauda epididymis were unchanged by hypothyroidism.

Animals↗

PubMed1990

Histochemical and histological analysis of the Leydig cells of cats treated with a supraphysiological dose of LH-RH analog.

An LH-RH analog (des-Gly10,[D-Trp6]-LH-RH ethylamide, LH-RH A) was administered to adult male cats for 67 days (20 micrograms/kg, sc) in order to study its inhibitory effects on the structure of Leydig cells, as determined by histological and histochemical-morphometric techniques. Histological examination showed that LH-RH A promotes a decrease in the volume of the interstitial tissue. In addition, Leydig cell nuclei exhibited marked structural alterations. Morphometric analyses utilizing histochemistry of the enzyme 3-beta-hydroxysteroid dehydrogenase (3-beta-HOST-D) as a marker of Leydig cells also demonstrated a significant decrease of the relative volume occupied by the Leydig cells in the testis.

3-Hydroxysteroid Dehydrogenases↗

PubMed1990

Pituitary-testicular axis in benznidazole-treated rats.

Benznidazole is used extensively throughout Latin America as an antiparasitic chemotherapeutic agent against chagasic infection. We have shown that rats chronically treated with 80 mg benznidazole kg-1 day-1 for 30 days present severe testicular atrophy and arrest of spermatogenesis. In the present experiments, plasma levels of testosterone (T), luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (Prl) were investigated in rats receiving 10, 40 and 80 mg benznidazole kg-1 day-1 for 30 days. No significant change in T, LH, or Prl levels was observed in treated rats (P greater than 0.05). Plasma FSH concentration, however, was markedly increased (P less than 0.05) by benznidazole treatment (40 and 80 mg kg-1 day-1) and remained high for 90 days after drug treatment was discontinued.

Animals↗

PubMed1990

Saturnism in the male rat: endocrine effects.

The effect of exposure to lead on endocrine function was studied in pubertal rats treated with 1.0 g/l lead acetate (PbAc) in drinking water for 20 days (subacute group) or 9 months (chronic group) in addition to iv injections of PbAc (0.1 mg/100 g body weight) every 10 (subacute group) or 15 days (chronic group). Although basal levels of testosterone were higher both in the plasma and in the testes of acutely intoxicated animals, the circulating levels of luteinizing hormone (LH) were not affected in either group, nor was the LHRH content of the median eminence. The density of [125I]LH/hCG binding sites in testicular homogenates was reduced by saturnism in both groups. However, the apparent affinity constant of the hormone-receptor complex significantly increased. 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↗

PubMed1989

Testes alterations in pubertal benznidazole-treated rats.

To determine the side effects of benznidazole, an antiparasitic chemotherapeutic agent against chagasic infection, rats were treated with 80 mg benznidazole kg-1 day-1, p.o., for 30 days, while controls received the vehicle. Treated animals developed severe testicular atrophy (0.25 +/- 0.02 g/100 g vs 0.44 +/- 0.02 g/100 g for the controls), though plasma testosterone level, relative weight of seminal vesicles and prostate were similar to those of the controls. Histological examination of the testes revealed a statistically significant alteration in the spermatogenic process with a marked decrease in the frequency of meiosis, number of tubular sections with mature spermatids and depletion of germinal epithelium.

Animals↗

PubMed1988

A method for estimating the concentration of spermatozoa in the rat cauda epididymidis.

A method for estimating the concentration of spermatozoa in the rat cauda epididymidis is described. Treatment of a sperm suspension with 0.05% collagenase for 20-60 min or 0.025% trypsin for 1-2 min at 34-37 degrees C was found to result in consistently homogeneous sperm. Sperm concentration ranged from 152.5 to 230.0 X 10(7) spermatozoa/ml, with a mean of 187.7 (+/- 5.6 SEM) X 10(7) spermatozoa/ml.

Animals↗

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↗

PubMed1988

Stage-dependent variation in the rat Sertoli cells nuclear volume.

A morphometric study was carried out to investigate stage-dependent variation in sertoli cell nuclear volume in the rat testis. sertoli cell nuclei had the largest volumes in stages IX to X of the seminiferous epithelium cycle (746 microns3), and the smallest volumes in stage XIV (624 microns3). In the remaining stages, the nuclei presented intermediate values, without significant differences. The results were discussed in terms of a possible functional cyclic variation in the sertoli cell reflecting changes in their nuclear size.

Animals↗

PubMed1987

Determination of spermatozoa concentration in the rat cauda epididymidis.

A method for estimating the concentration of spermatozoa in the rat cauda epididymidis is described. Treatment of a sperm suspension with 0.05% collagenase for 20-60 min or 0.025% trypsin for 1-2 min at 34-37 degrees C was found to result in consistently homogeneous sperm. Sperm concentration ranged from 152.5 to 230.0 x 10(7) spermatozoa/ml, with a mean of 187.7 +/- 5.6 (SEM) x 10(7) spermatozoa/ml.

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↗