Recreational use of erectile dysfunction medication may decrease confidence in ability to gain and hold erections in young males.

We aimed to estimate the frequency of recreational use of erectile dysfunction medication (EDM) and to identify any adverse effects on confidence in gaining and holding erections resulting from such use. In addition, we explored differences in erectile function and sexual behavior between recreational and medicinal users of EDM to control for the possibility of recreational users having but not admitting erectile dysfunction. A subset from the Genetics of Sex and Aggression population-based sample of 4428 males with a mean age of 29.51 (s.d.=6.77) years provided information on their use of EDM, erectile function during first intercourse and currently, sexual behavior and confidence in their ability to gain and hold erections. There were 2.6% (n=115) recreational and 0.9% (n=39) medicinal users of EDM. Recreational users had currently significantly lower confidence in their erectile ability than non-users even though they had significantly better erectile function and significantly more unrestricted sexual behavior as well as had more confidence when initiating sexual activity. More frequent use of EDM was associated with significantly less confidence in erectile ability among the recreational users. We conclude that recreational users of EDM may be vulnerable for becoming psychologically dependent on pharmacologically induced erection.

The effect of blood signals on aggressive behaviour in mice.

The study examined whether blood applied to the coat of a male opponent mouse modifies the aggressive behaviour of the attacking male mouse. Interest was also focused on whether the signal value of blood is related to the location of different bite targets, and whether such communication is visually or olfactorily mediated. The subjects used in the study were male Turku Aggressive (TA) mice of the 57th generation of selection for high levels of aggressiveness. The 72 TA males were divided into six groups matched on the times of latency to the first attack in standard dyadic aggression tests. Different groups of male TA mice were tested against opponents with blood, a red solution or nothing applied to either both flanks or the forehead. Testing was discontinued after the first attack. The results showed that blood had an inhibiting effect on aggression unrelated to the location of its application. The opponents with blood applied to their coats were attacked significantly later and the TA males sniffed such opponents significantly more. Odours associated with blood presumably serve as signalling pheromones. The biological significance of blood signals is discussed.

Changes in male odours and urinary marking patterns due to inhibition of aggression in male mice.

The effects of active inhibition of aggression on male odours and urinary marking patterns were studied in mice belonging to a highly aggressive strain the TA (Turku Aggressive), which has been developed by selective breeding through 37 generations. These males were defeated by trained fighters until they showed no aggression. Individually housed TA males served as controls. Mice from the parental or Normal Strain, which is intermediate in aggression, were exposed to the odours. The males from the Normal Strain were tested for aggression against male castrates to which urine from the two types of TA males or water had been applied. The urine from the highly aggressive control TA males evoked most aggression. The Normal males were later tested against castrates on soiled sawdust. Fewer attacks occured on sawdust soiled by the urine from the control TA males. The preferences for areas covered with soiled sawdust were also assessed. The males from the Normal Strain preferred areas soiled by the TA males trained to nonaggressiveness while the females preferred areas soiled by the highly aggressive control TA males. Subsequently the size and number of urinary marks deposited were examined. The TA males trained to nonaggressiveness voided urine in fewer but larger pools. The differences showed the same direction as those previously found between the TA and TNA strains, selectively bred for aggression and non-aggression, respectively. In mice the odour signals and urinary marking patterns seem to be correlated with the level of aggressiveness, either hereditarily determined or acquired through learning.

Predatory behaviour in females of two strains of mice selectively bred for isolation-induced intermale aggression.

The study sought to determine whether females of two strains of mice selectively bred for high (Turku Aggressive, TA) and low (Turku Non-Aggressive, TNA) levels of isolation-induced intermale aggression display differences in predatory behaviour. Additional subjects used in the study were females of the parental strain (Normal, N). Another aim of the present research was to investigate whether predatory aggression is associated with the postpartum period in the TA and TNA females. Testing consisted of dropping a live cricket into the home cage of the experimental females. The results showed that the predatory behaviour of individually housed TA and TNA females did not differ significantly. The only difference found between the two groups of females was in digging behaviour, the TA females showing more of this activity element on the first day of testing. Experience was found to affect the behaviour of the mice, attacking and consuming increased over trials whereas sniffing and the latency to attack decreased. In another experiment, TA and TNA females were tested for predatory aggression on the third day postpartum. The TA and TNA females were found to differ in all other observed behaviour variables but sniffing. The TA females spent more time chasing, tail-rattling, attacking, and consuming, as well as showing shorter latencies to the first attack. The TNA females spent more time digging, grooming, and nursing. The results suggest that the mechanisms determining the dispositions for predatory and maternal aggression in females and isolation induced intermale aggression and predatory aggression in males are not entirely different.

Female aggression during gestation and lactation in two strains of mice selected for isolation-induced intermale aggression.

The present study investigated whether maternal aggression is related to male behaviour in two strains of mice selected for isolation-induced intermale aggression. The strains were selectively bred from an outbred Swiss albino stock for high (Turku Aggressive, TA) and low (Turku Non-Aggressive, TNA) levels of aggression in forty-seven generations. One hundred and forty individually housed TA and TNA females were administered a seven-minute aggression test involving adult male intruders. The aggression tests were performed on day nine and eighteen during the gestation period, and on day one, three, six, nine and twelve postpartum. Separate groups of animals were tested on each of these days. Maternal aggression was found to be related to intermale aggression in the selectively bred TA and TNA strains. During the gestation period the females of the two lines displayed differences only with regard to sniffing, whereas during lactation significant differences were observed in this regard, as well as in attacking and tail rattling. The aggressive behaviour of the TA females reached a peak on day three and nine postpartum.

Sex-related coping responses in mice selectively bred for aggression.

Sex differences in strategies of coping with novel situations were studied in three strains of mice with regard to metabolism and open-field and maze activity as well as learning-induced adjustment. The 140 mice were selectively bred for high (Turku Aggressive [TA]) and low (Turku Nonaggressive [TNA]) levels of aggressiveness and originated from a Swiss albino stock normally distributed [N] for aggressiveness. The results indicated that TNA sex differences are more similar to those of the control N mice as compared to those of TA mice. In maze learning, however, the sex differences of TA mice are more in agreement with those of the N strain. Recordings of metabolism and open-field as well as maze activity were correlates of both gender and strain. Sex differences in learning-induced open-field coping behavior were unrelated to strain.

Evidence for a genetic etiology to ejaculatory dysfunction.

A number of theoretical approaches to understanding the etiology of ejaculatory dysfunction have been proposed, but no study has yet found conclusive evidence that premature (PE) or delayed (DE) ejaculation is under genetic control. We conducted twin model fitting analyses on different indicator variables of ejaculatory function on a population-based sample of 3946 twins and their siblings (age 18-48; mean=29.9 years) to investigate genetic, shared environmental and unique environmental effects on PE and DE. A significant moderate genetic effect (28%) was found for PE. No clear-cut familial effect could be detected for DE. Significant associations between ejaculatory function and age were detected, but effects of age were generally very weak. The findings from the present study provide useful information regarding the etiology and understanding of ejaculatory dysfunction.

Correlated genetic and non-shared environmental influences account for the co-morbidity between female sexual dysfunctions.

BACKGROUND: Previous studies have shown moderate heritability for female orgasm. So far, however, no study has addressed the pattern of genetic and environmental influences on diverse sexual dysfunctions in women, nor how genetic and environmental factors contribute to the associations between them. METHOD: The sample was drawn from the Genetics of Sex and Aggression (GSA) sample and consisted of 6, 446 female twins (aged 18-43 years) and 1994 female siblings (aged 18-49 years). The participants responded to the Female Sexual Function Index (FSFI), either by post or online. RESULTS: Model fitting analyses indicated that individual differences on all six subdomains of the FSFI (desire, arousal, lubrication, orgasm, satisfaction, and pain) were primarily due to non-shared (individual-specific) environmental influences. Genetic influences were modest but significant, whereas shared environmental influences were not significant. A correlated factors model including additive and non-additive genetic and non-shared environmental effects proved to have the best fit and suggested that both correlated additive and non-additive genetic factors and unique environmental factors underlie the co-occurrence of the sexual function problems. CONCLUSIONS: The findings suggest that female sexual dysfunctions are separate entities with some shared aetiology. They also indicate that there is a genetic susceptibility for sexual dysfunctions. The unique experiences of each individual are, however, the main factors determining if, and which, dysfunction develops.

Selective breeding for isolation-induced intermale aggression in mice: associated responses and environmental influences.

Aggressive (TA) and nonaggressive (TNA) lines of mice were established by selective breeding for isolation-induced intermale aggression. This paper summarizes and updates studies performed on the TA and TNA lines. The genetic analysis revealed that in these lines the genes for aggression are located on the autosomes and demonstrate a Mendelian segregation. The genes are expressed only in the presence of androgens which are normally present only in males. Behavioral and biological responses associated with high and low levels of aggression in TA and TNA mice are reviewed. Line differences have been found in olfactory communication and marking behavior, in maternal and predatory aggression in females, in locomotor activity, and in learning abilities. Also, correlated neurochemical and endocrinological responses to the selection have been detected. Maternal factors during the preweaning period do not significantly affect the development of aggression in TA and TNA males, while early postweaning exposure to aggression or sex enhanced later aggressive and sexual activity. Early experience and genetic disposition for aggression are correlated, with TA males showing the greatest increase in the behaviors studied.

Predatory aggression in male mice selectively bred for isolation-induced intermale aggression.

Male mice differing in their genetically determined disposition for isolation-induced intermale aggression were compared on behaviors related to predatory aggression. An ongoing sequence of selective breeding established high-aggressive (Turku Aggressive: TA) and low-aggressive (Turku Non-Aggressive: TNA) lines from an outbred Swiss albino foundation stock. The parental strain, designated the Normal (N) strain, has been kept as a control line and is bred without regard to aggressiveness. Testing consisted of dropping a live cricket into the home cage of the individually housed experimental mice. Results showed that the TA males displayed shorter latencies to attack and spent more time in chasing, attacking, and consuming crickets than did TNA and N males. The TNA males displayed significantly less predatory aggression than both the TA and N males. When brothers of the males tested for predatory aggression were tested for intermale aggression, a similarly significant effect of breeding line was obtained for the latency to attack. Testing consisted of placing an intact male mouse into the cage of the male to be tested. The results suggest that there may be parallels in genetic variation between intermale and predatory attacking.

Sadomasochistically oriented behavior: diversity in practice and meaning.

One hundred and eighty-four subjects (22 women and 162 men) who were members of two sadomasochistically oriented clubs answered a semistructured questionnaire containing items relating to a variety of sexual behaviors. Using a multivariate statistical analysis that geometrically represents the co-occurrence of individual actions as a visual array (Guttman (1954). In Lazarfeld, P. E. (ed.), Mathematical Thinking in the Social Sciences, Free Press, Glencoe, IL.) four qualitatively different sexual scripts emerged: hypermasculinity; administration and receiving of pain; physical restriction; and psychological humiliation. Although similar themes have been suggested before, this study demonstrated their empirical base. Humiliation was significantly associated more with females and with heterosexual orientation in men, while hypermasculinity was associated with males and with homosexual orientation in men.

Effects of testosterone exposure and fighting experience on the aggressive behavior of female and male mice selectively bred for intermale aggression.

Exposure of female mice to testosterone resulted in aggressive behavior as a function of breeding line in two lines of mice selectively bred for high (Turku Aggressive, TA) and low (Turku Nonaggressive, TNA) levels of aggressiveness. Female TA mice that received a single injection of testosterone propionate (TP) (1 mg in 0.05 ml peanut oil) on the second day of life, and starting at 120 days of age received daily injections for seven consecutive days, displayed aggressive behavior on a level comparable to that of socially isolated males of the same line, whereas control TA females (injected with 0.05 ml peanut oil) and TP-exposed TNA females were totally nonaggressive. The level of aggressiveness was assessed by means of dyadic tests against intact male opponents. Early and adult exposure to TP did not lead to increased aggressiveness in male TNA mice. Fighting experience in combination with prolonged TP treatment changed the aggressiveness of the TP-exposed TA females, leading to decreased aggressiveness in defeated animals. The genetically correlated low level of aggressiveness of TNA male and female mice was unaffected by any combination of TP exposure, learning and social isolation. It is concluded that differences in testosterone reactivity of target organs, other than those which are Y chromosome determined, i.e., the testes, are responsible for the aggressiveness in the strains studied.