Reduced tolerance to morphine thermoregulatory effects in senescent rats.

摘要: Abstract Age-related differences in the thermoregulatory response to morphine have been shown rats. To determine if these age-related would be reflected acquisition of tolerance, we studied tolerance induced by either a single dose or implantation pellet. precipitated withdrawal was also analyzed inducing with naloxone morphine-pelleted Senescent (26 27 month old), mature (10 11 old) and young (3 4 male Fischer 344 rats were restrained changes rectal temperature monitored for six hours after administration. Only exhibited increased hyperthermic responses second low (5 mg/kg s.c.). became tolerant higher (25 All age groups showed three days pellet implantation. Hypothermia equivalent all when These results indicate that older more resistant thermic effects morphine; however; continued treatment, regardless age.