The effect of cyproterone acetate on motor activity, aggression, "emotionality", body weight and testes in wild mice

Androgen receptors and sociosexual behaviors in mammals: The limits of generalization

Circulating testosterone is easily aromatized to estradiol and reduced to dihydrotestosterone in target tissues and elsewhere in the body. Thus, the actions of testosterone can be mediated either by the estrogen receptors, the androgen receptor or by simultaneous action at both receptors. To determine the role of androgens acting at the androgen receptor, we need to eliminate actions at the estrogen receptors. Alternatively, actions at the androgen receptor itself can be eliminated. In the present review, I will analyze the specific role of androgen receptors in male and female sexual behavior as well as in aggression. Some comments about androgen receptors and social recognition are also made. It will be shown that there are important differences between species, even between strains within a species, concerning the actions of the androgen receptor on the behaviors mentioned. This fact makes generalizations from one species to another or from one strain to another very risky. The existence of important species differences is often ignored, leading to many misunderstandings and much confusion.

Androgen receptors, sex behavior, and aggression

Androgens are intricately involved in reproductive and aggressive behaviors, but the role of the androgen receptor in mediating these behaviors is less defined. Further, activity of the hypothalamic-pituitary-gonadal axis and hypothalamic-pituitary-adrenal axis can influence each other at the level of the androgen receptor. Knowledge of the mechanisms for androgens' effects on behaviors through the androgen receptor will guide future studies in elucidating male reproductive and aggressive behavior repertoires.

Étude pilote préliminaire de l’acétate de cyprotérone dans les comportements agressifs associés aux démences sévères

INTRODUCTION

Behavioral symptoms are common in dementia, and seem to be more frequent in men than in women. Agitation is frequently responsible for caregiver burn-out and leads to institutionalization. The dramatic increase in the prevalence of Alzheimer's disease and related disorders requires better management of behavior symptoms. Although environmental adaptation has been proposed recently, for many years, psychoactive medications and physical restraints were the primary approach. However, in severely demented patients, both pharmacologic and non-pharmacologic treatments are inoperative. In this situation, alternative pharmacologic approach should be tested. Cyproterone acetate, an antiandrogen and progestative steroid has never been proposed to prevent aggressive behavior in dementia, but its favorable effect is well described in rat and monkey aggressivity.

PATIENTS AND METHODS

Cyproterone acetate was proposed for 19 demented patients who developed severe aggressive behaviors or an agitation unresponsive to psychoactive drugs (even in association) or to environmental adaptation. Clinical and behavioral analysis was carried out using the Cohen-Mansfield agitation inventory associated with an assessment of dependency in daily life activities, before and during treatment with cyproterone acetate. The behavioral status was stable, with permanent or repetitive agitation. Seven patients had vascular dementia, 7 had Alzheimer's disease, 2 had fronto-temporal degeneration, 2 had Huntington's disease and 1 a probable diffuse Lewy bodies disease. Fifteen patients had prominent aggressive behavior and 4 had predominant aberrant motor behavior with aggressive behavior.

RESULTS

Cyproterone (50 to 100mg - mean: 92.5mg daily) improved significantly aggressive and impulsive behavior related to Alzheimer's disease or vascular dementia but had no effect on aberrant motor behavior. When cyproterone was stopped, aggressive behaviors reappeared more rapidly in vascular dementia.

CONCLUSION

Cyproterone acetate is then an interesting choice when aggressive behavior is not improved with psychotropic drugs. A detailed clinical analysis is required to avoid the use of cyproterone in non-aggressive and non-impulsive patients. The results of this preliminary study suggest a randomized double-blind study should be carried out in the near future. The behavior improvement could be related to the blockage of androgen receptors, and simultaneously to the sedative effect of progestative drugs.

Studies on the effects of the antiandrogen cyproterone acetate on social encounters between pairs of male mice

An attempt was made in two experiments to reinvestigate the effects of the antiandrogen cyproterone acetate (CA) on mouse social behavior in a variety of ethologically-assessed paired encounters. The data confirm that CA reduces offense (threat and attack) in animals when both subjects receive the material but that CA has no such action in other pairings. This suggests that CA's major suppressive effect on "hostility" is expressed in mice via a reduction in "attack-promoting" pheromone production. Indeed, there was evidence in the more chronic study that CA, could augment (via a central mechanism?) offense in subjects paired with docile anosmic opponents. Changes in defense were largely responses to variations in the degree of attack to which animals were subjected. The antihormone also had actions on other aspects of behavior including sexual activity, social investigation and immobility in such tests. CA had a potent suppressive action on the weights of sex accessory glands. The data do not suggest that CA can be used as a specific antihostility agent.

The effect of cyproterone acetate on shock elicited aggression in rats

The aggressive behavior of male rats treated chronically with cyproterone acetate was measured following electric footshock. Shock elicited fighting behavior and body weight was recorded once every week for 4 weeks. The level of plasma testosterone, brain 5-HT and 5-HIAA and weight of testes were measured 24 hours after the last injection. No significant change was observed in the level of testosterone or brain 5-HT and 5-HIAA. A trend towards an increase in plasma testosterone and shock elicited fighting in rats treated with a higher dose of CA (10 mg/kg) may be indicative of some androgenic property of CA. On the other hand a slower gain in the body weight and a significant reduction in the testes weight of CA treated rats corroborate the well known antiandrogen property of this steroid. The balance of these androgenic and antiandrogenic properties of CA may account for the absence of significant changes in behavioral and biochemical measures.

A method of quantitating aggressive behaviour revealing possible dissociation of motor activity and aggression

A method is described for quantitating isolation-induced aggression in wild male mice by measuring coarse motor activity. It is based on the operational definition that aggression is the form of motor activity in which two (or more) animals are involved in behaviour patterns, such as physical attack and/or defence including pursuit and flight. Both coarse and fine motor activity were measured by means of an electromagnetic activity meter. Four hundred ninety-two fights occurring among mice treated with various hormones, neurotransmitter antagonists, hashish, and cyproterone acetate were recorded; a positive significant correlation (P less than 0.001) between indices of fighting behaviour as well as fighting time and coarse motor activity were found. The simultaneous measurement of motor activity and aggression revealed dissociated effects of some drugs on non-aggressive fine motor activity and aggression.

Dissociated effects of inhibition of catecholamine synthesis on motor activity, "emotionality," and aggression in mice

The inhibitor of catecholamine synthesis at the tyrosine hydroxylase level, alpha-methyltyrosine, administered in daily doses of 250 mg/kg IP, altered motor activity and aggressive behavior of isolated male mice in ten-minute paired encounter tests conducted on nine successive days. Motor activity was determined by an electromagnetic activity meter which measures fine and coarse movements separately. Coarse motor activity correlated significantly with aggressive behavior. Nonaggressive fine motor activity was significantly increased, while all the parameters of aggressive behavior showed a significant decrease in aggression. Increased escape behavior, heterogrooming, squeaking, and two cases of stupor were observed, suggesting possible equivalents of anxiousness. The defecation rate did not differ from that of the control group, victors having had a higher rate than losers. Results are discussed in connection with the "construct of emotionality" and the hypothesis of there being several categories of aggression with corresponding biochemical correlations.