The potential of antiestrogens as centrally-acting antihostility agents: recent animal data

Serum estradiol levels and ethanol-induced aggression

The biological mechanisms behind ethanol-induced aggression are not known. Because gonadal hormones are linked both to aggression and ethanol, the present study examined relationships among the levels of serum estradiol (E2), testosterone (T), and aggressive behavior in ethanol-treated male mice. We found that among group-housed male mice, serum E2 levels were significantly elevated 30 min after a single injection of 0.6 g/kg ethanol. Serum T levels showed a nonsignificant decrease by ethanol. The E2/T ratio, an index of aromatization of T to E2, was significantly higher in the ethanol-treated animals when compared with the vehicle-treated animals. We also determined aggressive behavior in the resident-intruder test among isolated male mice at baseline (after a vehicle), and after an injection of 0.6 g/kg ethanol. The mice were grouped accordingly to those that increased, decreased, or remained nonaggressive in response to ethanol administration. We found that at baseline, neither serum T or E2 levels, nor E2/T ratio differed significantly between the increased or reduced aggressor mice. In contrast to the increase in serum E2 levels seen in the nonaggressive mice, ethanol significantly reduced circulating E2 levels, but did not affect aromatization of E2 from T in the mice that became aggressive following an ethanol injection. These data suggest that mice who exhibit a paradoxical decrease in serum E2 levels by ethanol may be particularly prone to ethanol-induced aggression.

Ethopharmacological studies on the effects of antihormones on rodent agonistic behavior with especial emphasis on progesterone

The effects of a range of antiandrogens and antiestrogens on conflict behaviors in laboratory rats and mice are reassessed in the light of recent studies applying ethophamacological analyses (recording the full spectrum of behaviors) to such investigations. It is argued that any antihostility properties of the antiandrogen cyproterone acetate are largely a consequence of indirect actions on odor communication, whereas antiestrogens (e.g., tamoxifen and CI 680) seem to have more fundamental motivational effects in addition to communicatory actions. A detailed example of the approach is provided in which progesterone (which can be antiandrogenic) is given to rats paired in different ways. The type of pairing has a very substantial effect on the actions seen after treatment, and the ethopharmacological approach generates a better picture of antihormone effect than traditional psychopharmacological tests.

Effects of prenatal exposure to benzodiazepine-related drugs on early development and adult social behaviour in Swiss mice--II. Antagonists

1. The present experiment examined, using a battery of tests, the effects of in utero exposure of Swiss mice to the benzodiazepine antagonists Ro 15-1788 and CGS 8216 upon early development and adult behaviour. 2. Early development was facilitated by treatment of Ro 15-1788. CGS 8216 suppressed during later development. Effects on the righting reflex were seen on different postnatal days following exposure to different treatments. The other factors studied remained unaffected. 3. Effects on adult social behaviour were examined using the resident-intruder paradigm, by determining the time allocated to broad behavioural categories. Increases in attack and threat in male offspring of dams treated with Ro 15-1788 and CGS 8216 were found. Female offspring differed from controls in digging and defensive/submissive behaviour.

Effects of prenatal exposure to benzodiazepine-related drugs on early development and adult social behaviour in Swiss mice--I. Agonists

1. The present experiment examined, using a battery of tests, the effects of in utero exposure to the benzodiazepine agonists chlordiazepoxide and midazolam upon the early development and adult behaviour of offspring of Swiss mice. 2. Early development was generally retarded as a result of treatment. 3. Effects on adult social behaviour examined using the resident-intruder paradigm by determining the time spent in broad behavioural categories, showed marginal effects due to chlordiazepoxide and more striking actions due to midazolam treatments. Generally the treatments produced changes suggestive of an increase and a decrease in anxiety in males and females respectively.

Effects of prenatal exposure to benzodiazepine-related drugs on early development and adult social behaviour in Swiss mice--III. Inverse agonists

1. The present experiment examined, using a battery of tests, the effects of in utero exposure to the benzodiazepine inverse agonists DMCM and FG 7142 upon the early development and adult behaviour of Swiss Mice. 2. Early development was respectively retarded and augmented by treatments with the higher and lower doses of DMCM. FG 7142 suppressed later development. DMCM retarded righting reflex on certain days. FG 7142 had a significant, biphasic effect on eye opening. 3. Adult social behaviour was examined using the resident-intruder paradigm, by determining the time spent in broad behavioural categories. Male offspring of dams treated with DMCM showed increased threat. FG 7142 had no significant effects.