FURTHER BY

ASPECTS

SUSTAINED

OF

HIGH Toshiie

AGGRESSIVE DOSE

SAKATA

and

OF

BEHAVIOR

THEOPHYLLINE

Hideaki

INDUCED IN

RATS*

FUCHIMOTO

The First Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan Accepted April 9, 1973

Abstract-Sustainedinjectionwith a high dose of theophyllineincreasedaggressive ness in rats in both behavioralratingsand paired fighting. In the latter test, 50 of theophyllinized pairs took the fightingpositionfollowinga hand-clapand the 75 of treated rats were dominantover controlpartners. In the open fieldtest, the theo phyllinizedrat dischargedfewerboluses,but there was no changein ambulatoryac tivity. The presentresultssupportthe findingin our previousstudythat demonstrated the productionof affectiveaggressionwith the chronic treatmentof theophylline. A previous study (1) has shown that the repeated administration of large doses of theophylline induced affective aggressive behaviors in rats. The purpose of the present report is to extend this study. I n order to achieve a quantification of this form of aggres siveness, the procedures of the aggressiveness rating, the reflexive fighting test and the open field test were utilized. MATERIALSAND METHODS Male albino rats of the Wistar strain, 95-110 days of age were used at the beginning of the experiment. 26 subjects were randomly divided into 14 as the theophylline group and 12 as the saline control. The dose of theophylline used was five mg in one m] saline per 100g body wt. and the same volume of saline was injected into the controls. During the experiment, each subject was injected i.p. twice daily for 20 days at a two hr interval. All subjects were restricted to 20 of their usual diet, but had free access to water. The open field, aggressivenessrating and the reflexive fighting tests, were performed to accomplish measurement of aggressiveness in rats. Each test was carried out once before and once after the course of injections. These three tests were done three, two and one day before and 17, 18 and 20 days after the injection, respectively. A more detailed description of the method is described in a previous report (1). Procedures were as follow: Open field testing-The area used consisted of a round field 60 cm in diameter with a sheet-tin wall 47 cm in height, painted flat gray except for thin red concentric circles and radial lines which divided the floor into 19 blocks. The field was illuminated by a 30-w fluorescent circle lamp with a shade from a height of 80 cm to diffusethe illumination as uniformly as possible over the field. Each subject was placed individually into the center circle of the field for a three minute period. Since Whimbey * Supportedin part by the PharmacopsychiatryResearchFoundation, and ScientificResearch grant No. 777196from the Ministryof Education,Japan.

(2) demonstrated that scores on the first day of open field testing do not reflect ones from day two onward, three trials were administered on the test day before the treatment and one trial on the day after. As for scores obtained before the treatment, only the scores on the third trial were used on data analysis. The following records were made for each trial: the total number of blocks entered (ambulation), frequency of rearing, preening and grooming, and the number of boluses dropped in the field throughout the testing. Aggressivenessratings-Animals were rated for aggressivenessby a modified Nauta's emotionality scale (3). The behaviors rated included: 1) reaction to visual presentation of a clamp; 2) reaction to a light tap on the back; 3) reaction to a light touch on the head; 4) response to a puff of air delivered over the entire dorsal surface of the body; 5) re sistance to capture; 6) amount and kind of vocalization during testing. For the first five measures, animals were given a score from zero to four, and from zero to two for mea sure six. Reflexive fighting test-Subjects were randomly assigned to pairs in each group. Paired animals were placed in an experimental chamber similar to that described by Bern stein and Moyer (4). The test cage used was 30,