Biomedical subjects

Y Wakafuji

Publications and source records attributed to Y Wakafuji.

13 recordsLinked to original sources

PubMed1996

Para-chloroamphetamine (PCA)-induced ejaculation in aged rats, semen analysis and artificial insemination.

The present study was undertaken to determine sperm motility and counts in semen yielded by para-chloroamphetamine (PCA)-induced ejaculation of aged rats which had lost their reproductive ability, and to attempt artificial insemination with suspensions of spermatozoa obtained in this way. The semen yielded by PCA-induced ejaculation from aged (75-week-old) rats had average sperm counts of 0.82 +/- 0.69 x 10(7), which were much lower than the average counts (9.42 +/- 1.65 x 10(7)) for semen spontaneously ejaculated by young adult rats (14 weeks old). However, 77.5% of the spermatozoa contained in the PCA-induced semen were rated as showing the most active movement. Spermatozoa collected in this way were injected into the upper parts of both uterine horns or into both ovarian bursae. Both methods made the females pregnant, but the results were better after injection into the ovarian bursae. The offspring born to these females showed no abnormalities.

Aging↗

PubMed1993

Effects of p-chloroamphetamine (PCA) on ejaculation in aged rats.

In general, sexual activity in normal animals declines with increasing age. In aged male rats, for example, no ejaculation occurs when paired with receptive females. The ejaculatory response induced by p-chloroamphetamine (PCA) in aged adult rats, 14 to 18 months of age, was observed. The animals were treated intraperitoneally with PCA. The ejaculation rates were 0.28.6, 57.1 and 100% at doses of 0.3125, 0.625, 1.25 and 2.5 mg/kg, respectively. These animals, with a few exceptions, showed an ejaculation within 2 hrs of PCA injection. These data for aged adults are similar to those for young adults.

Aging↗

PubMed1993

[The change with age of the copulatory behavior of the male rats aged 67 and 104 weeks].

Changes with age in sexual fertility in male rats of the Wistar-Imamichi strain were investigated. Litter size and numbers of implantation sites in females mated with males aged 14 to 44 weeks tended to decrease with increased aging of males. These indicators in females mated with males aged over than 44 weeks decreased, compared with that aged 14 to 44 weeks (P < 0.05 to 0.001). In addition, all females mated with males aged 95 weeks were not pregnant. In male copulatory behavior with aging, incidences and numbers of mounting at 67 and 104 weeks of age were 100%, 42.6 +/- 15.3 (Mean +/- S.D.) and 42%, 1.8 +/- 2.8, respectively. The intromission and ejaculation were observed at 67 weeks, but not at 104 weeks of age. These incidences and frequencies were 86%, 10.3 +/- 10.2 for intromission, and 43%, 1.0 +/- 1.3 for ejaculation. Mount latencies (ML) at 67 and 104 weeks of age were 535.4 +/- 607.9 and 3,822.0 +/- 1,753.4 sec, respectively. There were significant differences in ML between two groups (P < 0.05). At 67 weeks of age, intromission and ejaculation latencies, and post-ejaculatory intervals were 2,563.0 +/- 2,216.3, 1,633.7 +/- 977.6, and 657.3 +/- 320.6 sec, respectively. The pregnant rate and numbers of implantation sites in females mated with males aged 67 weeks were 43% and 5.4 +/- 6.8, respectively. In females mated with males aged 104 weeks, all were not pregnant. The weights of tests, epididymides, ventral prostate and seminal vesicles at 104 weeks were light, compared with those at 67 weeks of age (P < 0.05). From these results, the copulatory behavior in male rats of the Wistar-Imamichi strain declined with aging. Sexual fertility in males aged 67 weeks decreased in less than 50%, and males aged 104 weeks showed no intromission and ejaculation.

Aging↗

PubMed1993

[Fertility of male Syrian hamsters paired with one, two and four proestrous females each].

In order to improve the productivity of Syrian hamsters, we investigated whether a male could impregnate overnight more than one proestrous female. Twenty-one males and 49 females aged 8 to 10 weeks were used in this experiment. The mating systems were as follows: one male was paired with one female, one male was paired with two females, and one male was paired with four females. Six out of 7, 7 of 14 and 4 of 28 females became pregnant and gave birth under these three systems, respectively. We conclude that it is possible for a male to impregnate overnight about one female under the above mating systems.

Animals↗

PubMed1992

Effects of naloxone and naltrexone on receptive and proceptive behaviors in female rats.

The sexual receptive and proceptive behaviors induced by opiate antagonists, naloxone and naltrexone in estrogen-primed ovariectomized rats were observed under the presence of sexually active males. The females were treated intraperitoneally with naloxone or naltrexone at doses ranging from 0.5 to 4.0 mg/kg and the sexual behavior of females was tested before and after the injection of drug. The results obtained suggest that the opiate antagonists play a role in the regulation of lordosis behavior, but not proceptive behavior in female rats.

Animals↗

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↗

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↗

PubMed1980

[Variation in the number of nipples in Wistar-Imamichi rats (author's transl(].

In order to determine heritability of accessory nipples, variations in the number of nipples were investigated in 13-week old female Wistar-Imamichi rats, maintained as a closed colony in the Institute for Animal Reproduction. Most of the females examined (93.32%) had six pairs of nipples; three in the pectoral and three in the abdomino-inguinal regions. Whereas, 229 out of 3606 rats had one accessory nipple each, 9 animals had 2 accessories, and 3 females were deficient of the pectoral nipple. Most of the accessory nipples were found either in the caudal and cranial regions of the third pectoral nipples or in the regions between the second and third abdomino-inguinal nipples. The frequencies for appearance of the accessory nipples were higher in the pectoral regions than those in the abdomino-inguinal ones, and also in the left side than in the right (p < 0.01), respectively. In 208 out of 791 litters examined, 177 litters had only one sister-mate with accessory nipple, 29 litters had 2 sister-mates with accessories, and 2 litters had 3 sister-mates with accessories, respectively. The localization of accessory nipples of the sister mates within the litter was similar in most of the cases. Heritability of the appearance of accessory nipples was estimated to be 0.8074 by using the formula described by Falconer.

Animals↗