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

The possibility that naloxone-precipitated opiate withdrawal behaviors varied qualitatively over the course of the year was investigated. The experiments were carried out at monthly intervals over a 2-year period using rats treated with a morphine-containing slow-release emulsion. The results obtained from these experiments were equivocal, neither providing support for seasonal variance in the expression of the opiate abstinence syndrome, nor showing a complete lack of time-related differences. Although some behavioral signs of opiate abstinence showed seasonally related alterations in frequency over one of the years, this was not consistent from one year to another. It was therefore concluded that no significant relationship between the severity of the abstinence syndrome and the time of the year in which the experiment carried out could be demonstrated.