Biomedical subjects

R Hokao

Publications and source records attributed to R Hokao.

27 records · Page 2Linked to original sources

PubMed1992

[Effect of age on the copulatory behavior of the male rat].

Fifteen male SPF Wistar-Imamichi rats, aged 10, 27 and 44 weeks, that had been raised in the authors' laboratory, were used for the observation of copulatory behavior. Each male was given the opportunity to mate with a proestrous female. During a two hour period, standard measures of copulatory behavior, e.g., mounting, intromission and ejaculation, were documented by a video recording. The following results were obtained; the number of ejaculations in 10-week-old rats, over a two hour period, was 6 to 8. Males showed a subsequent post-ejaculatory interval. The males aged 27 weeks performed 3 to 4 times during the first hour, and then refrained from sexual activity. The copulatory behavior in males aged 44 weeks declined, as compared with that of their 10 and 27 weeks old counterparts.

Aging↗

PubMed1991

Copulatory behavior of sexually inexperienced male voles paired with proestrous females.

The copulatory behavior in sexually inexperienced male voles aged 9-13 weeks old was observed under dim red illumination. Proestrous females were used as stimulus voles in copulatory behavior tests. A 30-min test session was recorded. All males showed at least one ejaculation within 30 min. In addition, the pattern of copulatory behavior in male voles was compared to that reported previously in male hamsters. The frequencies of mount, intromission and ejaculation in male voles were similar to that in male hamsters but there were significant differences in the latencies of mounting, intromission, ejaculation and post-ejaculation between the two species.

Animals↗

PubMed1991

p-Chloroamphetamine-induced ejaculation and the 22-kHz vocalization of the male rat.

It is well known that the male rats paired with receptive females emit the 22-kHz vocalization after ejaculation. The question addressed is whether after ejaculation injected with PCA without receptive females the 22-kHz call would be emitted. Emission of the 22-kHz call in males injected by PCA was not observed after ejaculation.

Animals↗

PubMed1991

Central effects of yohimbine on copulatory behavior in aged male rats.

It is well known that yohimbine has a history of popular use because of its supposed aphrodisiac properties. The present study was done to determine whether yohimbine can modify the copulatory behavior of aged male rats. Adult male rats of the Wistar-Imamichi strain, 52 weeks of age and weighing 600-650g, were injected intracerebroventricularly with yohimbine hydrochloride (5, 10 micrograms/10 microliters/rat) or vehicle. Each male was then given the opportunity to mate with a receptive female for 30 min after administration of yohimbine or vehicle. Yohimbine produced significant decreases in the latency to initial mounting and significant increases in the number of mountings. However, there was no ejaculation in the yohimbine-and vehicle-treated males. This study is the first to clearly establish an important modulator of sexual arousal for yohimbine in aged male rats.

Aging↗

PubMed1991

Ejaculations induced by p-chloroamphetamine (PCA) in rats, hamsters and mice.

The ejaculatory response induced by p-chloroamphetamine (PCA) in male rats, hamsters and mice was observed during 2 hours after the injection. The animals were treated intraperitoneally with PCA at doses ranging from 0.78125 to 160 mg/kg. The ED50 (effective dose in 50% of animals) values of PCA for the initiation of ejaculation in rats and hamsters were 1.3397 (1.0732-1.6725) and 0.1105 (0.0802-0.1522) mg/kg, respectively. On the other hand, no ejaculation was observed in any mice at any doses examined. So we concluded that there are species differences in the ejaculatory response, induced by PCA, among rats, hamsters and mice.

Animals↗

PubMed1990

Nursing behavior in lactating rats--the role of the vomeronasal organ.

The vomeronasal organ (VNO) of female Wistar-Imamichi rats was removed completely. The females were impregnated and gave birth to young. The question addressed was whether such dams would show deficits in nursing behavior. The data indicated that removal of the VNO severely depressed nursing behavior. We conclude that the VNO contributes to the nursing behavior of lactating rats.

Animals↗

PubMed1988

Incidence of lordosis behavior in the female rat following removal of the vomeronasal organ.

The lordosis behavior in female rats following removal of the vomeronasal organ (VNO) was observed for a period of 14 hrs by means of a video camera monitor. Although the VNO-ablated female rats received a large number of mounts (96 to 204 times) by sexually active males, they showed only low scores (8 to 22) of lordosis quotients (number of lordosis behavior displayed/number of mounts X 100). In contrast, sham-operated females showed the highest lordosis quotients of 100 as was expected.

Animals↗

PubMed1986

[An outbreak of Trichophyton mentagrophytes infection in a rat breeding stock and its successful control].

An outbreak of dermatophytosis by Trichophyton mentagrophytes infection was observed in a breeding stock of the Wistar-Imamichi rat. Typical cutaneous lesions such as alopecia and hyperkeratosis due to the fungus were observed in 10% and 44% of adult females, and males respectively. No infection was seen in infant, even in those fostered by infected females. By 3 repeated cultivations of the hair, T. mentagrophytes was isolated from 107 (90.7%) of 118 rats clinically diagnosed as dermatophytosis. In order to maintain the original stock, the usual wholesale slaughter program was avoided and the following control measures were taken. After sacrificing all rats with the cutaneous lesions, the breeding colony was transferred temporarily to a separate animal room. The resulting vacant room was then disinfected 3 times with 10% formalin, followed by spraying with 3% sodium propionate solution 3 month later. The progenies from the non-infected mothers were dipped into 3% sodium propionate solution and transferred back into the disinfected animal room for re-colonization. Frequent sterilization of all equipment with iodophor, balsam and formalin was carried out. The room sterilized monthly with iodophor and 70% alcohol. Daily observation of all rats and monthly screening by culture test was done thereafter. As a result, no infection has been detected 4 month after recolonization, except for the 3 rats which were sacrificed immediately after detection. On the basis of the culture test and clinical observation, no infection was observed in the treated rat colony for the next five following years. Therefore, the effectiveness of these procedures of the eradication of T. mentagrophytes infection from a rat colony was shown to be quite reliable.

Animals↗

PubMed1984

[Increase in litter size and decrease of post-implantation loss of fetuses observed in an SPF colony of Wistar-Imamichi rats].

The number of delivered offspring, corpora lutea and implantation sites was observed in an SPF colony of Wistar-Imamichi rats bred in a barrier system free of specified microorganisms and parasites and was compared with that of rats bred under conventional conditions. The litter size of 6142 SPF rats ranged from 1 to 20, averaging 12.4 +/- 0.04, a value significantly higher (P less than 0.001) than that of conventionally bred rats (11.0 +/- 0.04). Although the number of corpora lutea was also higher in SPF rats than under conventional conditions, the number of post-implantation losses in SPF rats with less than 10 offspring showed a marked decrease compared with conventionally bred rats. These results show that the number of delivered offspring is higher in SPF rats than in conventionally bred rats and indicate that the increase in litter size is due to the increase in the number of corpora lutea and decrease in post-implantation loss of embryos of fetuses.

Animals↗