Differential effect of environmental temperature on morphine physical dependence and abstinence

1) Ambient temperature (T_a) significantly influenced the display of 4 of the 14 naloxone-precipitated withdrawal signs (nesting, flat posture, vocalization, dyspnea) in morphine-dependent, non-hibernating ground squirrels ($\text{Citellus}$$\text{lateralis}$).2) Analysis of variance performed on the six quantified signs revealed that T_a during withdrawal, but not during the development of physical dependence, was a significant factor in determining the expression of two signs (nesting and vocalization).3) The interaction between the influence of T_a during the periods of morphine administration and abstinence was a significant factor in determining the expression of nesting behavior, a finding that is consistent with the natural role of nesting as a behavioral thermoregulatory response.4) We conclude that environmental temperature modulates the expression of selected components of the naloxone-precipitated abstinence syndrome in $\text{C. lateralis}$ without exerting a measurable influence on the development of morphine physical dependence itself.