Modulation of male mouse genital sniff, attack, and mount behaviors by urogenital substances from estrous females.

The modulation of attacks, genital sniffs, and mounts in male SJL/J mice by ovarian-dependent urogenital substances in the urine voided by estrous females was examined. Urogenital substances were applied onto the external urogenital areas of ovariectomized mice. When compared with urine voided by estrous females, which stimulated genital sniffing, mounting, and reduced aggression, bladder urine was ineffective. Genital sniffing and mounting was stimulated by estradiol-17 beta, vaginal fluids, and preputial extract. Aggression was reduced by estradiol-17 beta, urethral catheterized urine, and vaginal fluids. Preputialectomy reduced, but did not eliminate, urinary stimulation of genital sniffing and mounting. Preputial extract stimulated aggression. Urogenital substances from ovariectomized females were ineffective in reducing attacks and stimulating genital sniffs and mounts. It was concluded that the ovarian-dependent chemosignals in the urine voided by estrous females are contributed by the urethra, vagina, and preputial gland, perhaps in part through the excretion of unconjugated estrogens.

Modulation of male mouse sniff, attack, and mount behaviors by estrous cycle-dependent urinary cues.

Modulation of male urogenital sniff, attack, and mount behaviors by urinary cues from female mice (SJL/J) was assessed in two experiments. Experiment 1 examined the efficacy of urine from ovariectomized and intact females in modulating the behavior of sexually experienced and inexperienced males vis-à-vis the control substance, water. It was found that urine from ovariectomized females showed no behavior-modulating properties, whereas urine from intact females decreased attack but increased sniff and mount behaviors in male mice. These findings are indicative of ovarian-dependent chemosignals contained in the urine of only intact females. Prior sexual experience had no effect on behavior of males when exposed to urine from ovariectomized females. Sniff and mount behaviors were, however, increased when sexually experienced males were exposed to urine from intact females. Using sexually inexperienced males, Experiment 2 assessed the chemosignal activity of urine from females in each of four estrous phases. It was determined that urine from proestrous and estrous females increased sniff and mount behaviors and decreased attack behavior. Urine from metaestrous females was shown to possess only sniff-inducing and mount-reducing chemosignal properties. Urine from females in diestrous lacked attack- and mount-modulating chemocues but may possess a sniff-inducing chemosignal.

Latent aggression-promoting properties of mouse bladder urine activated by heat.

The aggression-promoting property of bladder urine in adult male mice was investigated. Under a newly developed stimulus application procedure (i.e., camel hairbrush applicator). Experiment 1 determined the minimal volume at which bladder and voided urine educed agonistic behavior in agressors. It was found that at least 0.05 ml of bladder urine and 0.03 ml of voided urine, both from intact males, were needed to induce significantly more attacks and uro-anal sniffs than respective urine types from castrated males. Also, bladder urine educed significantly less agonistic behavior than voided urine, both from intact males. Hence, the presence of a weak bladder urine chemosignal was confirmed. From these and previous findings, it was hypothesized that the chemocommunicative property of the weak bladder urine chemosignal could be accentuated by releasing the prochemosignal(s). Using 0.03 ml as the urine volume in Experiment 2, it was shown that heating bladder urine at 37 degrees C educed significantly more agonistic behavior than freezing bladder urine. The heating of bladder urine, however, effected significantly fewer attacks than the freezing of voided urine. It was concluded that bladder urine contains a latent and a free chemosignal, both of which are weak relative to voided urine chemosignal activity.

An accessory sex gland aggression-promoting chemosignal in male mice.

The present study investigated male murine accessory sex glands as potential sources of a urinary aggression-promoting chemosignal. Experiments 1-4 were designed to determine whether the removal of the following glands would eliminate voided urine chemosignal activity: vesicular and coagulating glands, Cowper's gland, prostate gland, or preputial gland. The findings indicate that only preputialectomy eliminated the aggression-promoting properties of voided urine, which provides evidence that this gland is a necessary condition for chemo-activity. The efficacy of the preputial gland as sufficient for chemosignal production was examined in Experiment 5. Urine from males that had an intact preputial but removed vesicular, coagulating, Cowper's, and prostate glands was assessed and shown to possess the chemocue. It was concluded that the presence of a functional preputial gland is a necessary and sufficient condition for providing an accessory sex gland aggression-promoting chemosignal.

Murine aggression induced by a boar chemosignal: a stimulus presentation dependency.

Male mice were used to assess for the presence of aggression-promoting cues in the boar chemosignal, 5 alpha-androst-16-ene-3-one. The findings of Experiment 1 indicated that this steroid has no aggression-promoting properties when mixed in water. When mixed in urine from castrated males, however, the steroid was shown to induce agonistic behavior in aggressors. Thus, the steroid was shown to possess aggression-promoting cues when associated with urine. Experiment 2 was designed to assess the chemosignal properties of the steroid when mixed in urine or juxtaposed either proximally or distally to urine. It was determined that the steroid needed to be either adjacent to or mixed in urine for chemosignal activity to be evidenced. It was concluded that (1) urine may function as an orienting stimulus for the appropriate detection of the steroid or (2) the conjoint presentation of the steroid and urine provided a qualitatively different stimulus complex than either stimulus presented alone. The findings of both experiments question the species specificity of the boar chemosignal and have methodological implications for studies attempting to isolate a chemocommunicative substance. Appropriate stimulus presentation procedures need to be considered for future research projects.

beta-Glucuronidase activation of latent aggression-promoting cues in mouse bladder urine.

The present study was designed to investigate the chemical properties of the aggression-promoting cues present in bladder urine of male mice. The results of the first experiment confirmed earlier work by demonstrating the presence of an aggression-promoting chemosignal in bladder urine. In Experiment 2, behavioral assays were separately performed on the organic and aqueous layers of bladder urine obtained by repeated dichloromethane extractions. Only the combined organic layers of the initial three extractions demonstrated behavioral activity. A fourth extraction showed no behavioral activity for both organic and aqueous layers. However, the findings of Experiment 3 showed that incubation of the aqueous layer from the third CH2Cl2 extraction in beta-glucuronidase can free additional aggression-promoting cues into a subsequent CH2Cl2 extraction. It is concluded that two forms of the aggression-promoting chemosignal are present in bladder urine. One is lipophilic and behaviorally active, whereas the other is conjugated, possessing latent chemosignal properties.

Social chemosignals in five Belontiidae (Pisces) species.

Approach behaviors toward conspecific chemical stimuli of the opposite sex were examined in five Belontiidae species: Betta splendens, Macropodus opercularis, Colisa labiosa, C. lalia, and Trichogaster trichopterus. Approach was measured by (a) preference for section 1 of a three-section tank, which contained a vertical tube that introduced the stimulus water, and (b) occupancy of the tube. Experiments 1A and 1B showed that (a) approach behaviors were displayed by the isolated male Betta only to ripe-female stimulus water, (b) group-housed males of the remaining four species were not attracted to female-conditioned water, and (c) socially isolated males of these four species preferred section 1 during presentation of either ripe- or nonripe-female-inhabited water but occupied the tube only during exposure to ripe-female-conditioned water. The findings of Experiment 2A were that (a) the female Betta, regarless of physiological state, showed approach behaviors to male-inhabited water and (b) only ripe females of the remaining species indicated a preference for section 1 during male-water exposure but performed no tube entries. Results of Experiment 2B indicated that social isolation of the females, especially ripe females, facilitated their approach behaviors.

Chemical modulation of agonistic display in Betta splendens.

Mirror-induced aggressive display of male Siamese fighting fish was reduced by water-borne traces of (a) a pair of male combatants, (b) a nondisplaying fish of either sex, and (c) bits of torn cadual fin. These findings may indicate a mechanism whereby males tolerate the presence of conspecifics to permit nonagressive social interactions.