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Abstract

The present article summarizes our recent work on the contribution of serotonergic (5-TH) and benzodiazepine (BDZ) receptors in agonistic behaviour using ethopharmacological technology. After an introduction, in which the basic principles of ethopharmacology of agonistic behaviour in rats are explained, our work on serotonin and benzodiazepines is illustrated using four animal aggression paradigms, viz, resident-intruder, colony, hypothalamically-induced aggression (EBS) and maternal aggression in lactating female rats. Using a broad scala of serotonergic receptor ligands, including drugs influencing 5-TH1A, 5-TH1B, 5-TH1C, 5-TH2 and 5-TH3 receptors (both agonistic and antagonistic), we were able to postulate that only the 5-TH1B - receptor is specifically involved in the modulation of offensive aggressive behaviour in rats. Other receptor types are either not involved or in a nonspecific manner. Based on such ethopharmacological techniques we have developed specific antiagressive drugs, serenics. These drugs have a high affinity for the 5-HT1B receptor, thereby confirming our hypothesis. In contrast to serotonin agonists, BDZ-agonists (benzodiazepines) enhance aggressive behaviour, at least at low dosages. This socalled pro-agressive action was subject to extensive ethological investigations and appeared to depend on baseline levels of aggression, tyoe of opponent, level of experience and type of paradigm used. Ethopharmacology is a very worthwhile approach when trying to develop specific drugs (e.g. serenics) or unravelling the (behavioural) mechanims of action and the underlying motivational aspects (anxiety, depression, etc).