1985 年 105 巻 8 号 p. 775-783
The methamphetamine-induced stereotypy of mice in a three-dimensional open field divided into nine unit spaces was visually observed. Each space was a little larger in size than the mice. The resultant positional behaviors were analyzed by use of four measures, namely, total frequency of visits to unit spaces (N), spacial distribution of the animal location (H1) obtained by the equation H1=-Σ__ipilog2pi (bits), where pi was the frequency of visits to a unit space numbered as i/N, approximated visit direction (HII) obtained by the equation HII=-Σ__(i, j)pipijlog2pij (bits), where pij was the frequency of visits from the i unit space to a unit space numbered as j/frequency of visits to the i unit space, and visit direction from the 6th unit space (H6→) obtained by the equation H6→=-Σ__jp6jlog2p6j (bits), where p6j was the frequency of visits from the 6th unit space to the j unit space/frequency of visits to the 6th unit space. By increasing N methamphetamine gave and maximum effect at 2-4 mg/kg, s.c., but dose-dependently reduced the entropies, that is, HI, HII and H6→. Haloperidol (0.1-1 mg/kg, p.o.), metoclopramide (1-10 mg/kg, p.o), chlorpromazine (3-30 mg/kg, p.o.) and sulpiride (1-100 mg/kg, i.p.) dose-dependently antagonized the methamphetamine (8 mg/kg, s.c.)-induced stereotypy. These results suggest that the present method is useful for the analysis of stereotypy and a better understanding of pharmacological activities of antipsychotic drugs.