[Application of operant conditioning techniques to forensic toxicology: experimental studies on alcohol and abusable drugs].

This paper describes some experiments that apply the operant conditioning techniques to forensic toxicological research. These techniques may be useful in investigating the mechanisms of action, toxic symptoms, legal competence and drug metabolism associated with substance abuse such as abuse of alcohol, psychotropic drugs, narcotics, stimulants, and organic solvents. 1) Genetic research on alcohol preference in rats. We applied operant conditioning to investigate alcohol preference in rats and constructed an apparatus for the measurement of discriminated operate responses for water or alcohol reinforcement in rat. This apparatus is a modified Skinner box with a one-lever two-liquid system. Fixed ratio-10 (FR-10) schedules of reinforcement are used to increase the work of the rat before it obtains the reinforcement. The voluntary choice of water or 10% ethanol by the rat can be assessed quantitatively by measuring the lever-pushing responses. It is an extremely useful method for measuring the real alcohol preference of rats. A rat was kept in a Skinner box overnight. The numbers of responses and reinforcement for water and ethanol and the volumes of the two liquids consumed were recorded. The ratio of ethanol reinforcement was defined as the number of ethanol reinforcement to the total number of ethanol and water reinforcement. The ratio of ethanol intake was defined as the volume of ethanol consumed to the volume of water and ethanol consumed. Ethanol consumption per g body weight was calculated from the volume of ethanol consumed by the rat. We used this apparatus to investigate alcohol preference of more than 300 Wistar Albino Rats, and divided them into a high alcohol preference (HAP) group and a low alcohol preference (LAP) group. Inbreeding between littermates was conducted in each of the HAP and LAP groups. The liver tissue of each offspring was obtained and the cytosol fraction was collected and subjected to isoelectric focusing using polyacrylamide gel with a pH range of 3.5 to 9.5. Examination of the electrophoretic patterns of the acetaldehyde dehydrogenase (ALDH) revealed polymorphism in cytosolic ALDH 1. We confirmed that the polymorphism follows Mendel's law of inheritance, and is governed by two codominant alleles. Moreover, the polymorphism of ALDH 1 observed in Wistar strain rats correlated closely with the differences in ethanol consumption behavior or alcohol preference. 2) Effects of abusable drugs on learning behavior of rat. In general, animal experiments for assessing drug effects, regardless whether they measure learning or intrinsic motor or physiological function, use behavioral indicators that produce a positive or negative reinforcement. In other words, the behavioral effect of a drug is assessed by whether it enhances the animal's behavior in a positive reinforcement or decreases its response in a negative reinforcement. However, the behavioral indicator of the animal is rarely an independent entity within the body, but is closely associated with other behavioral components. Even when a behavioral indicator is enhanced by a drug, whether the apparent increase is due to the enhancing effect of the drug or a result of decreases of other behavioral components cannot be judged. We therefore devised a multiple active/passive avoidance learning apparatus which is a device for analyzing drug effects in rats using a running-wheel. We used this device to assess the effects of a drug on the animal from three dimensions simultaneously; excitatory, inhibitory and discriminatory behaviors. From these we attempted to clarify the overall effect of the drug on high order learning behavior of animal. This method enables direct examination of the so-called "learning capability" of an animal, which cannot be elucidated by single scheule learning that is strongly influenced by behavioral characteristics such as excitation and inhibition. Therefore, a method which uses avoidance learning as indicator is the best method