Sexual behavior and fertility of male rats submitted to prolonged immobilization-induced stress

In order to investigate whether prolonged stress interferes with the onset of sexual behavior at puberty and with fertility at adulthood, prepubertal male Wistar rats (40 days of age) were immobilized 6 h a day for 15 days (up to early puberty) or for 60 days (until sexual maturity). Pubertal stressed rats showed a two-fold increase in the latency for the first mount (probably due to repeated aversive experience in which a change of environment was always followed by immobilization) and a 2.5-fold increase in the frequency of thrusting (indicative of enhanced sexual performance). The apparently stimulatory effect of prolonged stress on the onset of sexual behavior is discussed in terms of increased testosterone level and interference with the complex interchanges between the neurotransmitters/neuropeptides involved in the central control of male sexual activity. Adult stressed animals were mated with normal females, which became pregnant but exhibited a more than two-fold increase in both pre-implantation and post-implantation loss, probably due to a smaller rate of fertilization and/or fertilization with damaged spermatozoa

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 per cent and 48 per cent, respectively, while plasma luteinizing hormone and testosterone presented a significant decrease of 29 per cent and 37 per cent, 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 per cent and the spermatozoon concentration in the cauda epididymidis by 32 per cent. A 17 per cent reduction in weight and a 42 per cent 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.

Sexual development of hypernatriophilic male rats up to puberty

The sexual development of normonatriophilic (Normo) and hypemrntriophilic (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 per cent NaCl) had a 20-39 per cent body weight reduction and a 22-29 per cent testicular growth rate decrease compared to Normo rats. Plasma testosterone (ng/ml) of Normoo rats increased from 0.29 ñ 0.02 at 30 days to 1.42 ñ 0.18 at 50 days, decreasing to 0.87 ñ 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 ñ 0.03) than in Normo (0.43 ñ 0.06) rats at 40 days. At 30 days, plasma follicle stimulating hormone (FSH) levels (ng/ml) were significantly higher in Hyper (18.9 ñ 1.3) than in Normo (15.6 ñ 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 per cent 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 per cent lower rate of testis maturation. Testis maturation was similar in Hyper and Normo rats at 60 days.

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 tests were collected, frozen in liquid N2 and stored at -70oC 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 with decreased levels of androgens (A = 0.26 +/- 0.06 ng/g 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 prebubertal age, while only P levels (3.12 +/- 0.51 ng/g, control = 1.73 +/- 0.27 ng/g) were incresead in rats of early pubertal...

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)

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 repetion pulse rate, 200-*s pulse width, 30-V peak-to-peak amplitude and 20-mW/cm* 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