Pharmacology Biochemistry & Behavior, Vol. 38, pp. 889--891. ©Pergamon Press plc, 1991. Printedin the U.S.A. 0091-3057/91 $3.00 + .00 Measuring Anxiety in Nonhuman Primates: Effect of Lorazepam on Macaque Scratching GABRIELE SCHINO,*t ALFONSO TROISI,:~ 1 GEMMA PERRETTA§ AND VINCENZO MONACOt *Dipartimento di Genetica e Biologia Molecolare, Universit?t di Roma La Sapienza, Rome, Italy :'Laboratorio Animali da Esperimento, C.R.E. Casaccia, E.N.E.A., Rome, Italy $Cattedra di Clinica Psichiatrica, H Universit~ di Roma, Rome, Italy §lstituto di Medicina Sperimentale del C.N.R., Rome, Italy Received 25 June 1990 SCHINO, G., A. TROISI, G. PERRETrA AND V. MONACO. Measuringanxiety in nonhuman primates: Effect oflorazepam on macaque scratching. PHARMACOL BIOCHEM BEHAV 38(4) 889-891, 1991.--Lorazepam (0.2 mg/kg IM) was given to group- living female macaques to assess the effect of anxiolytic treatment on scratching, a behavior pattern referred to as a displacement activity in the primate literature. Lorazepam selectively diminished scratching behavior. The drug effect was status-dependent: es- pecially low-ranking animals showed a marked reduction in scratching. Lorazepam exerted a direct effect on scratching, that is the effect was not due to sedation or mediated by the influence of the drug on other behaviors. These results provide pharmacological validation to the ethological finding that scratching may be a manifestation of anxiety in monkeys. In addition, they suggest to use scratching as a behavioral measure in studies investigating nonhuman primate models of anxiety. Anxiety Scratching Nonhuman primates Benzodiazepines Displacement activities Animal models Ethopharmacology MOST animal models relevant to the topic of anxiety have been developed as systems for identifying drugs that may have anxi- olytic properties in humans, rather than as attempts to detect emo- tional states in animals equivalent to the experience of anxiety in humans (7). Such models generally involve experimental para- digms employing highly aversive stimuli unlikely to occur in fe- rai environments (e.g., electric shock). File (4) has argued that these situations of conditioned fear, where a predictable and ob- jectively unpleasant effect is expected, are different from those involving uncertainty, an emotion which may more closely ap- proximate the human experience of anxiety. It is reasonable to assume that some of the most compelling analogs, if not homologs, to human anxiety can be found among man's closest living relatives, the higher nonhuman primates. Nonhuman primates living in a complex social environment fre- quently experience situations of impending aggression, danger, conflict, or uncertainty. Ethological studies [e.g., (2,11)] have documented that, under these circumstances, monkeys tend to display certain behaviors that are apparently out of context and consist of different body care activities such as scratching, self- grooming, body shake, and yawning. These behaviors, which are referred to as "displacement activities" in the ethological litera- ture, seem to show a resemblance to clinical anxiety which is in some respects superior to that of conflict paradigms in rodents. First, displacement activities occur in response to common social situations not involving physical pain. Second, in nonhuman pri- mates, these behaviors do not occur only as responses to acute frightening stimuli but also as responses to more subtle situations somehow perceived as threatening, but where no immediate threat is apparent to the animal. This f'mding is interesting in relation to the clinical notion that human anxiety often depends on the "meaning" attributed to a given stimulus or situation (13). However, there is as yet no conclusive evidence that displace- ment activities are valid measures of anxiety in nonhuman pri- mates. Pharmacological studies are an important component of the research strategy for validating displacement activities as a primate model of human anxiety. The present study aimed at as- sessing whether scratching by group-living monkeys is selectively diminished by lorazepam, a pharmacologic agent which is anxi- olytic in humans. In addition to scratching, other social and non- social behaviors were recorded to exclude the possibility that changes in scratching were due to nonspecific or indirect effects of the drug. 1Requests for reprints should be addressed to Alfonso Troisi, M.D., via Guattani, 14, 00161 Roma, Italy. 889