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Biomedical subjects

A K Slob

Publications and source records attributed to A K Slob.

At least 73 records · Page 4Linked to original sources
PubMed1991

Perinatal flutamide and mounting and lordosis behavior in adult female Wistar and Sprague-Dawley rats.

The present study was designed to investigate the possible role of perinatal androgens acting via the androgen receptor, as opposed to the estrogen receptor, for the differentiation of adult mounting and lordosis behavior in female rats. Female Wistar (W) and Sprague-Dawley (SD) rats were exposed to the anti-androgen flutamide prenatally (days 11-22 of pregnancy) and/or neonatally (days 1-10). The females were ovariectomized in adulthood and repeatedly tested for mounting and lordosis behavior. Flutamide, given both pre- and neonatally to SD rats, reduced adult T-induced female mounting. Flutamide administered only prenatally or only neonatally did not lower adult mounting behavior of SD rats. Mounting behavior of female W rats, following pre- and/or neonatal flutamide treatment was not affected. Lordosis behavior was also not altered by perinatal flutamide treatment of either strain. The results of the present study, no effect of prenatal flutamide, do not support the hypothesis that female rats require prenatal androgen receptor-mediated actions of testosterone in the organization of neural tissues for the occurrence of adult mounting and lordosis behavior. Only in SD rats androgenic organization of adult mounting behavior via the androgen receptor seems to occur both pre- and neonatally. Since clear behavioral effects of prenatal flutamide treatment have been published earlier in Long-Evans females, we suggest strain differences in sensitivity for perinatal androgenization in female rats. Future research into that possibility is needed.

Animals↗
PubMed1991

Menstrual cycle phase and sexual arousability in women.

Sexual arousability of women has not been consistently found to vary significantly over phases of the menstrual cycle. We studied changes in the temperature of a labium minus and subjective sexual and genital arousal recorded on semantic scales while watching erotic video in 12 women with natural menstrual cycles and 12 women using low-dose estrogen oral contraceptive pills. Natural cycle phase was ascertained by blood progesterone. Subjects were tested twice, with an interval of about 2 weeks. Half of each group had their first test during their luteal phase, the others during their follicular phase. Women tested for the first time in their follicular phase were sexually more aroused than women tested for the first time during their luteal phase. This was true for both objective (i.e., a labium minus change in temperature) and subjective genital arousal. When these women were retested in their alternative phase of the menstrual cycle, those who were then follicular did not score higher than those who were then luteal. On the contrary, the latter group scored as high as when tested during their follicular phase. This phenomenon was observed both in women with and without oral contraception. The nature of the menstrual phase (i.e., natural or pill-induced) seems irrelevant in this respect. Sexual arousal achieved during the first session appeared to be correlated with an increase in desire for making love during the rest of the day and night. Only 1 of 12 women tested during their luteal phase indicated an increase in desire to make love, while 6 of 12 women tested during their follicular phase indicated an increase. Apparently the menstrual cycle phase during the first test determines the immediate response and indirectly affects the response during the second test approximately 10 days later. In a random block design the difference in sexual response between follicular and luteal phase of the menstrual cycle disappears.

Adult↗
PubMed1991

Adult partner preference and sexual behavior of male rats affected by perinatal endocrine manipulations.

Intact adult male rats, in which aromatization of testosterone to estradiol was prevented pre- and/or neonatally by ATD (1,4,6-androstatriene-3,17-dione), were repeatedly tested for partner preference behavior (choice: estrous female vs active male). In consecutive tests increasing preference scores for the female were found. Neonatal ATD males showed significantly lower preference scores for an estrous female than controls or prenatal ATD males. Prenatal ATD caused preference scores only slightly lower than those of controls. Ejaculation frequencies were markedly reduced or even absent in neonatal ATD males. Prenatal ATD treatment only had no or a moderately lowering effect on ejaculation frequency. Lordosis behavior of adult intact males was more facilitated following neonatal ATD treatment than following prenatal ATD treatment. In a number of tests the serotonergic drug 8-OH-DPAT was injected prior to testing for sexual partner preference and copulatory behavior. DPAT significantly increased preference for an estrous female in all groups of males when interaction was possible, but had no effect when sexual interaction was prevented by wire mesh. DPAT was able to increase the number of ejaculators in nonejaculating groups (i.e., perinatally ATD-treated males). "Premature ejaculations," i.e., ejaculations with the first intromission, were frequently observed with DPAT treatment in all groups of males. In conclusion, the availability of neonatal estrogen (derived from testosterone) organizes, at least partially, the preference for an estrous female normally shown by adult male rats. The lack of neonatal estrogen causes males to be less masculinized, both in partner preference behavior and ejaculatory behavior, and less defeminized in lordosis behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Neonatal organization of adult partner preference behavior in male rats.

Male rats were castrated or sham castrated shortly after birth. Castrated males were then injected every other day on days 0-10 with testosterone propionate (TP, 0.5 mg), dihydrotestosterone propionate (DHTP, 0.5 mg) or the oil vehicle (0.05 ml); sham-castrated males received oil injections. In adulthood, when substituted with DHT, DHT + E2, or T (silastic implants), sexual partner preference was measured in an automated open field (AOF), in which wire mesh prevented sexual interaction with incentives, and in a 3-compartment box (3-CB), in which sexual interaction with tethered incentives was possible. Choices were an estrous female and a nonestrous female or an estrous female and a sexually active male. In adulthood, following long-term treatment with DHT or DHT + E2, the males did not show any partner preference when sexual interaction with incentives was prevented. Following sexual experience with an estrous female these males preferred the estrous over the nonestrous female, although this change could also be due to long-term hormone treatment. In the 3-CB, a clearcut preference emerged for the estrous female over the nonestrous conspecific, although the neonatally DHTP- or oil-treated males scored lower than the neonatally TP-treated or control males. Six weeks after removal of the hormone implants, when tested in the 3-CB (estrous female vs. active male), the males showed no partner preference. Unexpectedly the control males showed a low preference for the active male. Three weeks T-treatment made all males show a preference for the estrous female (in 3-CB).(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗
PubMed1991

On the organization of partner preference behavior in female Wistar rats.

The possible prenatal organizing effects of testosterone (T) on adult sexual partner preference, i.e., sexual orientation in female rats, were studied through prenatal exposure (days 11-22) of female fetuses to the antiandrogens flutamide (Sch 13521; 4'-nitro-3'-trifluoromethylisobutyranilide; 5 or 10 mg/day; Experiment 1) or anandron [RU 23908; 5,5-dimethyl-3-(4-nitro-3-(trifluoromethyl)phenyl)- 2,4-imidazolidinedione; 35 mg/kg/day; Experiment 2]. The neonatal organizing effects of T were further studied by giving T, dihydrotestosterone (DHT) or oil within 9 h after birth to female pups (Experiment 3). In adulthood sexual orientation was ascertained, after ovariectomy followed by hormone treatment, in an automated open field (AOF), with stimulus animals behind wire mesh, and in a 3-compartment box (3-CB), with stimulus animals tethered. When given the choice between an estrous female and a sexually active male in the AOF, flutamide females, as well as controls, preferred the male partner. After long-term T treatment and 3 weekly pair-tests with an estrous female, flutamide females as well as controls switched their preference to the estrous female partner. In anadron females similar results were obtained. Thus the prenatal antiandrogens had no significant effect on sexual orientation in female rats. This suggests that adult sexual orientation in female rats is not organized prenatally through endogenous T. The change in preference after sexual experience corroborates earlier findings from our laboratory. When given the choice between an estrous female and a sexually active male in the 3-CB (sexual interaction with incentives possible), neonatally DHTP-treated females preferred the male; neonatally TP- or oil-treated females showed no preference.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgen Antagonists↗
PubMed1991

Sex behavior of male and female Wistar rats affected by the serotonin agonist 8-OH-DPAT.

Four experiments were carried out to test the stimulatory effects of 8-OH-DPAT on various aspects of "masculine" sexual behavior of male and female rats and on the sexual attractivity of male rats. In Experiment 1 8-OH-DPAT (0.2 mg/kg) stimulated ejaculation frequency in middle-aged (approx. 15 months old) males, both sexually inactive and active subjects. There was a coinciding decrease in total number of mounts, intromissions, intromissions to first ejaculation and latency to first ejaculation. In Experiment 2 the effects of two doses (0.2 and 0.4 mg/kg) 8-OH-DPAT on the first ejaculation cycle were investigated. Especially, the higher dose made a high percentage (45-55%) of males to ejaculate "prematurely," i.e., at the first or second intromission. Latency to ejaculation decreased. With the higher dose, 25-35% of the males ejaculated extravaginally. In Experiment 3 8-OH-DPAT did not make males more attractive for an estrous female than saline-treated males, as judged by the time spent in their vicinity. However, estrous females received much more ejaculations from the tethered 8-OH-DPAT males, with the lowest latencies to first ejaculation, than from the saline-treated males. In Experiment 4 8-OH-DPAT stimulated mounting behavior in female rats only when they were long-term treated with testosterone. In that condition also shortest latencies to first mount were found with 8-OH-DPAT treatment.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1991

Changes in penile sensitivity following papaverine-induced erection in sexually functional and dysfunctional men.

To understand more clearly the role of penile sensitivity in sexual functioning, changes in penile thresholds resulting from papaverine-induced tumescence were studied in men who were either sexually functional or suffering from erectile dysfunction. Variable vibratory tactile stimulation was applied to 2 different sites, the base and tip of the underside of the penis. With standard psychophysical methodology, subjective thresholds were determined from a minimum of 5 threshold crossings. Results indicated a significant elevation in threshold after intracavernous papaverine injection, even though only partial erection was induced in most subjects. Men with erectile dysfunction had higher thresholds than control subjects but no difference in sensitivity was found between the base and tip of the penis. These findings indicate that low penile sensitivity is characteristic of some, although not all, men experiencing erectile problems and that this sensitivity is even lower during tumescence.

Adult↗
PubMed1991

Sex difference in whole-body androgen content in rats on fetal days 18 and 19 without evidence that androgen passes from males to females.

The whole-body content of androgen (testosterone + 5 alpha-dihydrotestosterone) was significantly higher on Fetal Days 18 and 19 in male than in female rats; androgen content was equivalent in the two sexes at other fetal ages, including Days 16, 17, 20, and 21, and prior to parturition on Fetal Day 22. These results partially corroborate previous data of Weisz and Ward (Endocrinology 1980; 106:306-316), who measured testosterone in pooled plasma from rat fetuses and suggest that androgens contribute to masculine brain sexual differentiation only briefly during fetal life. No significant differences in whole-body androgen content were observed among groups of females situated in utero between 0, 1, or 2 males on each side (contiguous male model) or among groups of females with 0, 1, or 2 or more males located caudally (on the cervical side) in the same uterine horn, regardless of whether combined data from Fetal Days 17-22 or only Fetal Days 18 and 19 were considered. These results provide no evidence that androgens from males reach female fetuses in the same uterine horn.

Androgens↗
PubMed1990

Masculinization and defeminization of female rats by males located caudally in the uterus.

It is assumed that female rats are masculinized by the presence of males in the same uterine horn. Two hypotheses regarding the mechanism have been proposed: 1) interamniotic diffusion of androgens (contiguity hypothesis) and 2) transport of androgens via the bloodflow (caudal male hypothesis). This study was designed to test these hypotheses while taking into account two previously uncontrolled factors: hemihysterectomy of the mother during pregnancy and birth by caesarean section. Pregnant females were hemihysterectomized during pregnancy or left intact; pups were born naturally or through caesarean section. Position in utero was determined. In adulthood all females were ovariectomized and tested for mounting behavior before and during testosterone treatment and lordosis behavior during estradiol treatment. It was found that females with males located caudally in the same uterine horn were more masculinized and defeminized than females without such males. Adjacent males had no influence on the behavioral sexual differentiation of females. These results confirm the "caudal male hypothesis" rather than the "contiguity hypothesis." Hemihysterectomy during pregnancy prevented the "caudal male effect." Birth through caesarean section did not interfere with the caudal male effect.

Animals↗
PubMed1990

Erection problems in medical practice: differential diagnosis with relatively simple method.

Functional sexual potency can be assumed when penile erection occurs during visual erotic stimulation, and to a lesser degree with normal nocturnal penile tumescence. Erection, increase in circumference as well as rigidity, can be measured with a simple device consisting of a calibrated felt band with a sliding collar fastened to 1 end. Subjects were 58 consecutive patients, mainly from a urology outpatient department, with erection problems and 67 healthy control men. Changes in penile circumference were measured during viewing of an erotic videotape and during sleep. Functional sexual potency, at least partially, was presumed to exist in 41 patients (71%), many of whom had a somatic pathological condition that might easily have been believed to be the cause of the erectile dysfunction. During the latter half of the study nocturnal penile tumescence also was measured. This group included 7 patients who did not respond to the visual stimuli, 5 of whom had normal nocturnal penile tumescence. We conclude that the erection meter, in conjunction with an erotic video test and nocturnal penile tumescence measurements, is a useful and simple device in the differential diagnosis of erectile difficulties in men. This is true especially when elaborate sleep laboratory facilities and neurophysiological equipment are not available.

Adult↗
PubMed1990

Sexuality and psychophysiological functioning in women with diabetes mellitus.

Subjective and objective psychophysiological responses to erotic visual stimulation were recorded for 24 women with diabetes mellitus type I and 10 control women. There were no significant differences in subjective responses (general sexual arousal and genital arousal) between the two groups. The objective response, a rise in the temperature of the labium minus, varied with the height of the initial temperature. Since this temperature was significantly higher in diabetic women, the subsequent rise during erotic visual stimulation was less in diabetic women than in controls. When samples from the two groups were matched for initial temperature, the difference in the increase in labial temperature was no longer statistically different. In both groups of women there was a significant correlation between the degree of subjective arousal and the rise in labial temperature when women with a high temperature (greater than 37 degrees C) at the start of the visual erotic stimulation were not included. The absence of a statistically significant effect of diabetes mellitus on the parameters studied may be due to a lack of serious neuropathy and angiopathy in the present sample of diabetic women. Future psychophysiological studies should include women with serious neuropathy with or without diabetes mellitus.

Adult↗
PubMed1989

Preference for an estrous female over a non-estrous female evinced by female rats requires dihydrotestosterone plus estradiol.

The effects were studied of long-term treatment with testosterone metabolites (dihydrotestosterone. DHT, and estradiol, E2, in sc Silastic implants) on preference behavior of ovariectomized female rats for an estrous female over a non-estrous female. For measuring this behavior a residential plus-maze was used which harbored two ovariectomized "stimulus" females on the top of peripheral boxes, one of which was made estrus by injection of estradiol benzoate and progesterone. When both steroids (DHT plus E2) were circulating simultaneously they evoked preference for an estrous female, while neither steroid by itself sufficed. In earlier work with adult male rats castrated on the day of birth, E2 was effective in the absence of DHT. This sex difference, therefore, seems to have arisen before birth. Further, administration of DHT alone caused a profound lack of interest in both "stimulus" females, which cannot be fully explained by the reduced locomotor activity which has been found to be induced by DHT in earlier studies.

Animals↗
PubMed1988

Peripubertal castration of male rats, adult open field ambulation and partner preference behavior.

The validity of the hypothesis put forward earlier, that testicular secretions during puberty have an organizing effect on open field ambulation was examined. Male rats were castrated or sham-operated at days 21, 43 or 70. At the age of 17 weeks the males were tested in an automated, octagonal open field (3 consecutive days, 3 min/day) for locomotor activity. Male rats castrated at day 21 or day 43 ambulated more than sham-castrated controls. Males castrated at day 70 did not differ from sham-castrated controls. It thus appears that pubertal testicular secretion(s) organize adult open field locomotor activity in male rats. From 18 weeks of age partner preference behavior was tested in the same open field apparatus with one adjacent cage containing an ovariectomized female and an opposite one containing an ovariectomized female brought into heat. The females in the adjacent cages were separated from the experimental males in the octagonal cage by wire mesh. Peripubertally castrated males did not show a clear-cut partner preference, whereas the intact males preferred the vicinity of the estrous female. There were no differences among the males castrated either before, during or after puberty. Testosterone treatment (crystalline T in silastic capsules) caused peripubertally castrated males to prefer the estrous female. Thus, adult partner preference behavior does not seem to be organized by peripubertal testicular androgens.

Animals↗
PubMed1988

Fetal gender and aggression in pregnant stumptail monkeys (Macaca arctoides).

Agonistic behaviors of pregnant female stumptail monkeys, members of a large, well-integrated group continuously living together, were studied during 480 observation hours (over 32 months). A total of 28 pregnancies of 20 females occurred, resulting in 12 male and 16 female live infants. The main finding was a significant decline in aggression, both received and performed, during the course of pregnancy. There was no clear unequivocal effect of fetal gender on aggressive behavior of the mothers-to-be.

Aggression↗
PubMed1988

Partner preference behavior of estrous female rats affected by castration of tethered male incentives.

Estrous female rats were allowed to interact with either of two tethered intact male rats or to stay in an empty middle part of a three-compartment observation cage during a 60-min test. Sexual interactions occurred with both males (resulting in one to five ejaculations) but most time was spent in the empty compartment. After castration of one of the males, females spent more time with this male than with the intact male, although sexual interactions continued with both incentive animals. This "preference" for the castrated male persisted through the second hour of observation in a second experiment (total test time 115 min) although sexual interactions had virtually ceased during this period. Females' preference for castrated males seemed largely the consequence of aversion to genital stimulation received during intromissions by intact animals: (a) when intromissions were prevented through vaginal occlusion, intact males became by far the preferred partners for the whole 2-hr period of testing while sexual behavior continued to occur throughout the test; (b) when choice was allowed between a testosterone-treated ovariectomized female and an intact male, sexual interaction occurred with both tethered incentive rats but the female became the preferred animal. The results suggest that two opposite tendencies play a role in sexual motivation of estrous female rats: attraction resulting from the action of ovarian hormones on the central nervous system and rejection resulting from genital sensory stimulation through the male's genitalia.

Animals↗
PubMed1988

Behavioral aspects of puberty in group-living stumptail monkeys (Macaca arctoides).

Behavioral changes before and around the time of puberty were studied in a longitudinal manner in male and female stumptail monkeys. Around the time of testicular descent (mean age: 3.3 years) males started to become more aggressive towards adult males. Within two years following testicular descent males rose in rank with the support of others and reached stable (sub)top positions in the dominance hierarchy. In the female rank-stabilization took place gradually between one year before and two years after first ovulation (mean age: 3.7 years). Copulatory activity began about two (in females) to two-and-a-half years (in males) before reproductive capacity was attained. Female copulatory activity began to rise about six months before first ovulation, when they started to copulate with adult males. In males copulatory frequency rose sharply between six and twelve months prior to testicular descent. Until a few months after testicular descent males could copulate openly in the group without interruption; from about 1 year following testicular descent virtually all copulations had to take place surreptitiously to avoid interruption by higher ranking adult males. It is postulated that this decreasing tolerance of adults may contribute to the process of peripheralization and migration of young adult males which occur in free ranging macaque groups.

Aggression↗
PubMed1988

The role of the preputial glands in sexual attractivity of the female rat.

This study shows that olfactory cues contribute to attractivity of the female rat but that the preputial glands are a minor source of such olfactory stimuli. In the experiments described, a residential plus-maze was used. The amount of time resident male rats spent in the vicinity of an estrous female rat was used as a measure of female attractivity. In the first experiment it was shown that male rats were attracted to anaesthetized estrous female rats but that these females were less attractive than unanaesthetized estrous females. In the second experiment it was shown that after removal of the preputial glands females were still attractive for male rats. The results of the third experiment demonstrated that estrous preputialectomized female rats remained attractive for male rats when they were anesthetized. When the resident male rats could make a choice between an estrous preputialectomized female and an estrous control female there was a tendency for the latter to be preferred. It can be concluded that olfactory cues enhance the attractivity of an estrous female rat, but that it is not the only sensory modality used by the female to attract a (distant) male. The preputial glands are of minor importance as a source of olfactory signals.

Animals↗