Populations of follicles in F344/N rats during aging

Effects of aging and delivery order on the breeding capacity of F344/N rats

Reproductive performance affects the efficiency of the production of animals. Therefore, knowing the reproductive properties of each species or strain of animal is important for proper management of breeding stocks. To elucidate the reproductive properties of female F344/N rats, frequently used for longevity and gerontology research, we monitored the breeding duration, number of deliveries, litter size and weaning rate of their pups. The first delivery was observed at 2.9 ± 0.1 (mean ± standard deviation) months of age (M) and the last delivery was at 15.1 ± 1.8 M. The number of deliveries was 10.4 ± 2.8 (range of 7-16) within the life span of the mother (24.7 ± 5.6 M). The litter sizes at the third (10.0 ± 3.0) or fourth (10.3 ± 2.7) deliveries were higher than for other deliveries. The breeding outcome declined after the fifth delivery yielding reduced litter size or weaning rate, number of delivered mother. These results suggests that though female F344/N rats are able to deliver more than 10 times, the reproductive performance lowered after fifth delivery.

Antral follicle count, oocyte production and embryonic developmental competence of senescent Nellore (Bos indicus) cows

Information on the follicular population and oocyte quality of cows in the final period of reproductive life is scarce. The present study aimed to compare the antral follicle count (AFC), oocyte production and embryonic developmental competence of young versus long-lived and senescent Bos indicus beef cows. Nellore cows (Bos indicus) were classified into three groups according to age: young (4-9 years, n = 10), long-lived (14-17 years, n = 10) and senescent (17-23 years, n = 10). At a random time in the estrus cycle, the cows received cloprostenol sodium salt (0.5 mg, IM), estradiol benzoate (1 mg, IM) and an intravaginal P4 device (1.4 g). Five days later, the P4 devise was removed and oocyte collection (OPU1) was performed. A second OPU (OPU2) was performed 5 days after the first in order to aspirate only growing follicles. During each OPU, AFC and the number and quality of cumulus-oocyte complexes (COCs) were evaluated. Then, the COCs were placed in standard maturation medium (IVM), fertilized and incubated for 9 days. The data were subjected to ANOVA and Multinomial Logistic Regression. The AFC was smaller in long-lived and senescent cows in both OPU1 and OPU2 when compared to younger cows. There was no difference in AFC between OPU1 (19.9 ± 1.8) and OPU2 (17.6 ± 1.9) in young cows, however, more follicles were punctured in long-lived and senescent cows in OPU1 (12.0 ± 2.6 and 19.3 ± 4.6) than in OPU2 (9.2 ± 1.9 and 10.3 ± 2.3), respectively (P < 0.01). The numbers of COCs recovered from young cows (OPU1 = 14.2 ± 1.8; OPU2 = 8.4 ± 0.9) were higher than those obtained from long-lived cows (OPU1 = 5.9 ± 2.3; OPU2 = 4.3 ± 1.0) and senescent cows (OPU1 = 7.2 ± 3.0; OPU2 = 4.1 ± 1.7), respectively (P < 0.05). The cleavage rate did not differ between groups. However, the rate of blastocyst formation was higher for young (64.8%) and long-lived (65.0%) compared to senescent (16.5%) cows (P < 0.01). In conclusion our results indicate that the AFC is lower in long-lived and senescent cows compared with young cows. However, unlike in senescent cows, the embryonic development of long-lived cows is similar to that of young cows. This suggests that Nellore cows aged >17 years begin to have reduced embryonic development capacity due to ovarian aging.

Protective role of Ficus deltoidea against BPA-induced impairments of the follicular development, estrous cycle, gonadotropin and sex steroid hormones level of prepubertal rats

Ficus deltoidea is one of the well-known medicinal plants in Malaysia that is traditionally used by the Malay community to treat various ailments and for maintenance of female reproductive health. The objective of this study is to evaluate the potential protective roles of Ficus deltoidea against BPA-induced toxicity of the pituitary-ovarian axis in pre-pubertal female rats. In this study, four groups of pre-pubertal female Sprague Dawley rats were administered with the followings by oral gavage for a period of six weeks: NC (negative control- treated with vehicle), PC (positive control-treated with BPA at 10 mg/kg/BW), F (treated with Ficus deltoidea at 100 mg/kg/BW, then exposed to BPA at 10 mg/kg/BW) and FC (Ficus deltoidea control - treated with Ficus deltoidea at 100 mg/kg/BW). Daily vaginal smear, ovarian follicular development as well as gonadotropin and sexual-steroid hormone levels were determined. The findings showed that Ficus deltoidea demonstrated preventive role against BPA-induced toxicity on the ovaries. This was evident by the increased percentage of rats with normal estrous cycle, qualitatively reduced number of atretic follicles (as observed in histopathological examination) and normalization of the gonadotropins hormone (FSH) and sexual steroid hormone (progesterone) levels. In conclusion, Ficus deltoidea has the capability to prevent the effects of BPA toxicity in the hypothalamus-pituitary-gonadal axis of prepubertal female reproductive system, possibly due to its variety of phytochemical properties. Therefore, these findings strongly support the traditional belief that this medicinal plant is beneficial as daily dietary supplement for the maintenance of female reproductive health.

Age-dependent changes of the mandible bone throughout the lifespan in female F344/N rat

Age-dependent changes of the mandible bone in female F344/N rats, aged 22-1196 days, were analyzed using physiological bone properties and morphology. Bone weight, bone area, bone mineral components, and bone mineral density were assessed using dual-energy X-ray absorptiometry. The bone weight, bone area, bone mineral components, and bone mineral density increased rapidly until approximately 150 days of age, increased gradually thereafter, and then stabilized or decreased after 910 days of age. The ratio of bone mineral components to bone weight (bone mineral ratio) increased rapidly until approximately 43 days of age and stabilized thereafter. Size of the mandible, which was measured at 13 points on mandible surface, increased with age, and the rate of change showed a similar pattern to the other parameters. From a principal component analysis on morphometric measurements, principal component 1 (size factor) increased proportionally with age, whereas principal component 2 (shape factor) decreased until approximately 88 days of age and then increased after 365 days of age. As a result, the scatter plots for principal component 1 and principal component 2 were V-shaped, which indicates that the mandible developed in size, with deformation at younger ages, and recovered its original shape later in life. Our results revealed the occurrence of inflection points at approximately 43, 88, 150, 365, and 910 days of age. Some of these ages corresponded to transition points revealed by the age-dependent changes of the occlusal mandibular condyle and tooth wear in the same rat.

Ovarian function and reproductive senescence in the rat: role of ovarian sympathetic innervation

Successful reproduction is the result of a myriad interactions in which the ovary and the ovarian follicular reserve play a fundamental role. At present, women who delay maternity until after 30 years of age have a decreased fertility rate due to various causes, including damaged follicles and a reduction in the reserve pool of follicles. Therefore, the period just prior to menopause, also known as the subfertile period, is important. The possibility of modulating the follicular pool and the health of follicles during this period to improve fertility is worth exploring. We have developed an animal model to study the ovarian ageing process during this subfertile period to understand the mechanisms responsible for reproductive senescence. In the rat model, we have shown that the sympathetic nervous system participates in regulating the follicular development during ovarian ageing. This article reviews the existing evidence on the presence and functional role of sympathetic nerve activity in regulating the follicular development during ovarian ageing, with a focus on the subfertile period.

Free Spanish abstract: A Spanish translation of this abstract is freely available athttp://www.reproduction-online.org/content/153/2/R59/suppl/DC1.