Copulatory efficiency and fertility in male rats exposed perinatally to flutamide

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fertility of rat epididymal sperm after chemically and surgically induced sympathectomy

Guanethidine, a chemical that selectively blocks sympathetic noradrenergic neurons, was used to investigate the role of sympathetic innervation in the fertility of rat epididymal sperm, using both natural mating and in utero insemination protocols. This animal model correlates, at least in part, with spinal cord injury (SCI) in men. Adult male rats were treated daily by i.p. injections, for 21 or 42 days, with 0 or 6.25 mg/kg guanethidine. To compare the effects of guanethidine-induced sympathectomy with those following surgically induced sympathectomy, the inferior mesenteric ganglion and the proximal hypogastric nerves were removed in another group of rats. Both chemically and surgically induced sympathectomy increased the weight of the epididymis and seminal vesicles/coagulating glands as well as the number and the transit time of cauda epididymal sperm. Neither serum testosterone levels nor LH was affected by treatment with guanethidine. Using natural mating, no litters were produced by guanethidine-treated rats. Chemically denervated rats failed to produce copulatory plugs or ejaculate into the uterus. However, distal cauda epididymal sperm from chemically or surgically denervated rats displayed normal fertilization ability (80%) using in utero inseminations. In addition, the sperm of denervated rats did not show abnormal sperm chromatin structure using an assay that detects DNA damage. We conclude that sympathectomy delays the transit of sperm through the cauda epididymidis and produces ejaculatory dysfunction but does not compromise sperm quality in the distal cauda epididymidis. Moreover, these data provide compelling evidence that there is no association between the prolonged transit time of sperm within the epididymis, i.e., pre-ejaculatory sperm aging, and the fertility of those sperm, which has important implications for artificial insemination using sperm from men with SCI.

Impairment on sperm quality and fertility of adult rats after antiandrogen exposure during prepuberty

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphometric-stereological and functional epididymal alterations and a decrease in fertility in rats treated with finasteride and after a 30-day post-treatment recovery period

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Orchidopexy restores morphometric-stereologic changes in the caput epididymis and daily sperm production in cryptorchidic mice, although sperm transit time and fertility parameters remain impaired

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An explanatory mechanism for the different decline in limb strength in older women

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Habitat split and the global decline of amphibians

The worldwide decline in amphibians has been attributed to several causes, especially habitat loss and disease. We identified a further factor, namely habitat split- defined as human- induced disconnection between habitats used by different life history stages of a species- which forces forest- associated amphibians with aquatic larvae to make risky breeding migrations between suitable aquatic and terrestrial habitats. In the Brazilian Atlantic Forest, we found that habitat split negatively affects the richness of species with aquatic larvae but not the richness of species with terrestrial development ( the latter can complete their life cycle inside forest remnants). This mechanism helps to explain why species with aquatic larvae have the highest incidence of population decline. These findings reinforce the need for the conservation and restoration of riparian vegetation.

Seminal analysis, cryogenic preservation, and fertility in matrinxã fish, Brycon cephalus (Günther, 1869)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fertility tables of two populations of the parthenogenetic species Poratia salvator (Diplopoda, Polydesmida, Pyrgodesmidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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.

Fertility of male adult rats submitted to forced swimming stress

We investigated whether stress interferes with fertility during adulthood. Male Wistar rats (weighing 220 g in the beginning of the experiment) were forced to swim for 3 min in water at 32ºC daily for 15 days. Stress was assessed by the hot-plate test after the last stressing session. To assess fertility, control and stressed males (N = 15 per group) were mated with sexually mature normal females. Males were sacrificed after copulation. Stress caused by forced swimming was demonstrated by a significant increase in the latency of the pain response in the hot-plate test (14.6 ± 1.25 s for control males vs 26.0 ± 1.53 s for stressed males, P = 0.0004). No changes were observed in body weight, testicular weight, seminal vesicle weight, ventral prostate weight or gross histological features of the testes of stressed males. Similarly, no changes were observed in fertility rate, measured by counting live fetuses in the uterus of normal females mated with control and stressed males; no dead or incompletely developed fetuses were observed in the uterus of either group. In contrast, there was a statistically significant decrease in spermatid production demonstrated by histometric evaluation (154.96 ± 5.41 vs 127.02 ± 3.95 spermatids per tubular section for control and stressed rats, respectively, P = 0.001). These data demonstrate that 15 days of forced swimming stress applied to adult male rats did not impair fertility, but significantly decreased spermatid production. This suggests that the effect of stress on fertility should not be assessed before at least the time required for one cycle of spermatogenesis.

Perinatal estrogen exposure: Later repercussion on the fertility of rats

The aim of the present study was to investigate the effects of perinatal estrogen exposure in the fertility of rats. Thus, rats were treated with estrogen on the 21st or 22nd day of intra-uterine life or treated with estrogen immediately after birth. It was observed that the testicular descent of males and beginning of puberty of females were advanced in all estrogen-treated groups. The females from estrogen-treated groups showed reduced frequency of estrous in 15 consecutive days of study, and there was an increase in estrous duration. Their fertility also were impaired and a reduction in the number of alive fetuses, as well as enhancement of pre- and postimplantation loss, mainly in the group treated with estrogen on the 21st day of intra-uterine life. However, the alterations observed in the fertility of estrogen-treated male rats were slighter and only females mated with male rats from the group treated with estrogen immediately after birth showed enhanced preimplantation loss. We suggest that the reproductive function is impaired by exposure to estrogen in the perinatal life of rats, and that the mechanisms involved in this effect are distinct for males and females. (C) 1997 Elsevier B.V.