An experimental model which resembles human
drug addiction was developed to study the effect of chronic
drug (
cocaine or
morphine) administration on the immune system. As
malnutrition has been associated with
drug use, a
low protein diet has been evaluated for its contribution to the impairment of the immune system during
cocaine/
morphine addiction. Female C57BL/6 mice that received a 20% or 4%
casein diet were studied. Both drugs were administered intraperitoneally daily for 11 weeks and drugs were administered in increasing daily doses, beginning after 3 weeks of diet consumption. Doses of
cocaine began with 5 mg/kg
body weight and reached the maximum dose of 40 mg/kg/day at the fourth week. Doses of
morphine gradually increased from 10 mg/kg to 75 mg/kg
body weight with the maximum dose reached after 5 weeks of treatment.
Cocaine administration reduced
body weight, particularly in the
low protein diet group, and spleen weight in
protein malnourished mice.
Cocaine as well as saline injected mice showed a decrease in the percentage of CD4+ CD8+ and Mac-1+ cells and an increase in B cells in the spleens of well nourished mice.
Morphine-treated mice showed similar results to those observed in
cocaine or saline treated mice. These results suggest that
cocaine,
morphine or saline injection can alter the percentage of cells that express a defined phenotype independently of the nutritional status of the subject. Moreover, the effect appears dependent on a stress mediated process.