Effects of marking with preputial gland material on the attack directed towards long-term castrates by isolated males

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.

Effects of different doses of cyproterone acetate (CA) on preputial gland structure and activity in intact male mice

The preputial is an androgen-dependent structure which appears to be used in pheromonal signalling in rats and mice. The structure of representative glands from intact oil injected male laboratory TO strain mice was contrasted with tissue from intact counterparts treated with the anti-androgen cyproterone acetate (CA). Sixteen days of an i.m. application of a modest range of CA doses (0.5, 1.0 and 2.0 mg/day given as oily solutions) and a variety of control treatments were used to assess influences on the structure and function of the preputial. The glands of intact male mice treated with oil were well-developed and actively secreting with parenchymatous acini at different stages of maturation. Such glands are generally highly Sudanophilic, with the lipophilic stain concentrated in acini in frozen sections and many acini are compressed by their neighbours to assume irregular shapes. Wax and frozen preputial sections from intact subjects treated with 0.5 or 1.0 mg CA were, in contrast, less well-developed and had fewer and smaller lipid droplets. Treatment of counterparts with 2 mg CA reduced acinar number and diameter in both wax and frozen sections with a concomitant increase in the proportion of connective tissue. The data confirm that this anti-androgen antagonizes the androgen secreted by the testis and adrenal cortex in terms of its expression of function on the preputial gland. These data provide further evidence that cyproterone acetate's suppressive actions on murine aggression are primarily via its ability to depress the secretion of odour cues that facilitate attack.