A study on seasonal variation in the development of morphine dependence inrats

The possibility that naloxone-precipitated opiate withdrawal behaviors vari ed qualitatively over the course of the year was investigated. The experime nts were carried out at monthly intervals over a 2-year period using rats t reated with a morphine-containing slow-release emulsion. The results obtain ed from these experiments were equivocal, neither providing support for sea sonal variance in the expression of the opiate abstinence syndrome, nor sho wing a complete lack of time-related differences. Although some behavioral signs of opiate abstinence showed seasonally related alterations in frequen cy over one of the years, this was not consistent from one year to another. It was therefore concluded that no significant relationship between the se verity of the abstinence syndrome and the time of the year in which the exp eriment carried out could be demonstrated. (C) 1999 Elsevier Science Inc.