Streptozotocin-induced diabetes: significant changes in the kinetic properties of the soluble form of rat bone alkaline phosphatase.

A soluble form of an alkaline phosphatase, obtained from the osseous plate of streptozotocin-induced diabetic rats, was purified 90-fold with a yield of 26%. The calculated Mr of the purified enzyme was 80,000 by denaturing polyacrylamide gel electrophoresis and 160,000 by gel filtration on Sephacryl S-300, suggesting a dimeric structure for its native form. In the absence of metal ions, the p-nitrophenylphosphatase activity of the purified enzyme was 4223.1 U/mg. Magnesium or calcium ion concentrations up to 2 mM increased the specific activity of the enzyme to 9896.5 and 10,796.2 U/mg, respectively. The enzyme was stimulated to a lesser extent by MnCl2 (5390.1 U/mg) and CoCl2 (5088.2 U/mg). The purified soluble alkaline phosphatase showed a broad substrate specificity, and among the less hydrolyzed substrates were pyrophosphate (1517.6 U/mg) and bis-p-nitrophenylphosphate (499.6 U/mg). The enzyme was relatively stable at 45 degrees for periods as long as 180 min, but was denatured rapidly above 50 degrees, following first order kinetics with T1/2 values ranging from 3.5 to 57.7 min. The results reported herein suggested that the soluble form of alkaline phosphatase from streptozotocin-induced diabetic rats had its kinetic properties altered, apparently as a consequence of changes in metal-binding properties.

Low-intensity ultrasound energy applied to the testes of aged rats.

Previous studies from our laboratory have shown that low-intensity ultrasound applied to the scrotum of prepubertal rats causes a 62% increase in plasma testosterone, suggesting a possible stimulation of LH receptors and/or the enzymes controlling the steroidogenic process. The purpose of the present study was to investigate whether low-intensity ultrasound has a stimulatory effect on the androgenic activity of aged testes. In addition to plasma testosterone, LH and FSH, the testicular spermatogenic status was also analysed. Ultrasound applied to the scrotum of aged rats did not stimulate sperm production, which was significantly reduced compared to sexually mature animals, and failed to re-establish the steroidogenic testicular function, which was decreased by 74%, suggesting an inherent loss of gonadal steroidogenic competence.

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.

Ultrasound stimulation of rat testes damaged by busulfan.

The purpose of the present study was to investigate whether or not low-intensity ultrasound exposure (20 mW/cm2 average intensity) accelerates the repair of rat germinal epithelium damaged by an antispermatogenic agent. The results from analysis of testicular weight and DNA content, sperm production and epididymal sperm concentration showed that the time needed for the reestablishment of the spermatogenic process following busulfan treatment was not reduced by ultrasound energy suggesting that, in contrast to many other mammalian tissues, the seminiferous epithelium is refractory to ultrasound stimulation.

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.

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.

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)

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.

The male reproductive organs in experimental Chagas' disease. III. Plasma testosterone and accessory sex glands in the acute phase of the disease.

Male Wistar rats were injected i.p. with 2 x 10(5) trypomastigotes of the Bolivia strain. Fifteen days later, few parasite nests were observed in the fibromuscular layer surrounding the seminal vesicle acini of chagasic animals and no parasites were detected in the testis and ventral prostate. A significant decrease was observed in the absolute weight and fructose content of the seminal vesicle and ventral prostate of chagasic rats, which also presented a sharp decrease in plasma testosterone levels.

Morphometric study of the reversibility of thyroid alterations in rats submitted to hypervitaminosis A.

Administration of excess vitamin A doses to rats causes atrophy of the thyroid, with smaller follicles, more abundant cytoplasm, less colloid and decreased nuclear volume. The connective tissue were more abundant. In order to determine the possible reversibility of these alterations, the authors allowed the hypervitaminotic animals to recover for 30 days. After the recovery period, the glandular lesions were reversed to normal. These data were confirmed with morphometric technique.

Effect of hypervitaminosis A on tongue muscles of the rat. A morphometric study.

Daily administration of 200 I.U. vitamin A/gram body weight to rats, for a period of 10 days, causes generalized hypertrophy of the tongue muscles. The data were confirmed with morphometric techniques, consisting of increased cytoplasm and decreased nuclei and empty spaces, obtained by the Chalkley technique, nuclei of similar volume, obtained with the use of karyometry, and larger areas of cross-sections of muscle fibers.

Direct effect of low-intensity pulsed ultrasound on pubertal rat seminal vesicle.

Pubertal male Wistar rats were submitted to bilateral castration and killed 7 or 14 days later; an additional group of castrated rats was submitted to ultrasound stimulation of the ventral region lying above the accessory sex glands, for 20 min a day from the 7th to the 14th day postcastration. Control intact rats were age-matched to the different treated groups. Seminal vesicle growth and secretory activity were investigated on the basis of weight and fructose content, respectively. A progressive fall in seminal vesicle weight was observed over a period of 7 (83% decrease) to 14 (92% decrease) days following castration; ultrasound treatment beginning on the 7th day prevented this additional weight reduction. Castration caused also a marked decrease (50-60%) in the fructose content of the seminal vesicle and the ultrasound energy promoted a partial recovery of the secretory activity of the gland. The results revealed a direct ultrasound stimulation of the seminal vesicle secretory activity in pubertal rats deprived of testicular androgens.

Alcohol-induced alterations in the palate epithelium of the rat fetus.

Maternal alcoholism (ethanol and sugar cane brandy) during gestation induces delayed cellular growth and differentiation in fetal rat palate epithelium, with increased nuclear, cytoplasmic and cellular volumes, increased epithelial and keratin thickness and decreased cellular numerical density.

Morphometric study of the effect of hypervitaminosis A on the sublingual gland of the rat.

Hypervitaminosis A induces the following changes in the rat sublingual gland: smaller size acini with lower cells and smaller nuclei. The serous demilunes show smaller cells and nuclei. The striated ducts show smaller and disorganized cells with smaller nuclei. These data were confirmed by morphometric techniques.

Stimulation of prepubertal, pubertal and adult rat testis with low-intensity pulsed ultrasound.

Testes of prepubertal, pubertal and adult Wistar rats were stimulated with low-intensity pulsed ultrasound for 20 min a day, for 7 days. No significant changes were found in the spermatogenic activity as well as in plasma LH and FSH levels following ultrasound treatment. The testicular androgenic activity, however, was significantly increased in prepubertal treated animals, in addition to a significant increase in seminal vesicle growth and secretory activity. In spite of normal androgenic levels, pubertal treated rats presented also an increase in the seminal vesicle secretory activity, thus suggesting a direct action of ultrasound on the gland.

The salivary glands of Ameiva ameiva (Teiidae, Lacertilia). A morphological, morphometric and histochemical study.

The authors studied morphological, morphometric, and histochemically the mucosubstances and proteins in the salivary glands of the lizard Ameiva. Based on the results, the authors concluded: 1. The labial salivary gland is formed by small mucous and mucoserous glands; the sublingual gland by mucoserous cells. 2. Mucous cells show neutral and sulphated mucosubstances and sialic acid. Mucoserous cells of the labial gland show neutral mucosubstance, sialic acid, hyaluronic acid and protein radicals. Mucoserous cells of the sublingual gland show neutral mucosubstance, sialic acid and protein radicals. 3. The average values for acinar area were: 1,198.11 microns 2 for mucoserous acini and 2,105.95 microns 2 for mucous acini of the labial salivary gland. The average values for nucleus volume were: 47.41 microns 3 for mucoserous cells and 38.97 microns 4 for mucous cells. 4. The average values for acinar area and nuclear volume of the mucoserous cells of the subingual gland were respectively: 1,474.62 microns 2 and 67.77 microns 3.

Morphometric study of the effects of insulin on the rat submandibular gland.

After administration of an overdose of insulin, the following effects on the rat submandibular gland were observed: increased gland weight and acinar cell size, with increased cytoplasmic acidophilia and a larger number of secretory granules. The granular ducts showed higher cells and increased nuclear volume. The above data were confirmed by morphometric techniques. The total protein values for the submandibular gland were higher in rats 30 and 60 minutes after insulin overdose, when compared with those for control rats. Administration of an overdose of insulin caused a lowering of the glycemic level during the entire experimental period.

Glucose homeostasis during the early stages of liver regeneration in fasted rats.

Kinetic studies with [2-3H]glucose in vivo and gluconeogenic activity measurements in vivo and in vitro were performed in 70% hepatectomized rats submitted to fasting, which represents an extra burden for glucose synthesis but does not impair liver regeneration. Rates of glucose replacement, under steady-state conditions, 14 and 24 h postoperatively, did not differ in partially hepatectomized fasted rats and sham-operated controls. Phosphoenolpyruvate carboxykinase activities increased more rapidly during fasting in remnant livers than in intact livers from controls. Rates of incorporation of 14C from alanine into circulating glucose in hepatectomized rats were already maximal 14 h after surgery, whereas in controls they continued to augment. The maximal rates after partial hepatectomy could not be surpassed by performing the operation in diabetic animals. It is concluded that the relatively high blood sugar levels during fasting in hepatectomized rats do not depend on a reduced peripheral utilization of glucose, but only on a rapid increase in the gluconeogenic activity. The data suggest that hepatocytes in remnant liver can proliferate under conditions of maximal gluconeogenic and low glycolytic activities.

Morphometric and biochemical evaluation of rat prostate and seminal vesicle following chemical sympathectomy with guanethidine.

Selective chemical sympathectomy of the internal genital organs of adult male rats was undertaken by chronic treatment with low doses of guanethidine. Biochemical and morphometric methods revealed that removal of sympathetic innervation prevents fructose secretion in the prostate and seminal vesicle, in addition to promoting reduced efficiency of delivery by the latter.