Effects of acute systemic cocaine administration on the cortisol, ACTH and prolactin levels of black tufted-ear marmosets

The effect of acute systemic cocaine administration on total circulating cortisol, adrenocorticotropin hormone (ACTH) and prolactin levels of nine adult black tufted-ear marmoset monkeys (Callithrix penicillata) was investigated. For each subject, two blood samples were obtained after an i.p. injection of 10 and 20mg/kg of cocaine: one sample was drawn 30-min post-injection, while the second was following a 60-min interval. Blood samples were also obtained 0, 30 and 60 min following a saline injection. The 20 mg/kg dose of cocaine induced a significant decrease in ACTH levels 60 min after being administered. Circulating levels of cortisol, on the other hand, increased significantly 60 min after the 20 mg/kg dose. Prolactin concentrations decreased significantly 30 and 60 min after both doses of cocaine had been administered (10 and 20 mg/kg). Finally, the content of the three hormones analyzed remained constant 0, 30 and 60 min post-saline administrations. Therefore, an acute systemic cocaine challenge alters the basal circulating levels of ACTH, cortisol and prolactin of marmoset monkeys. A distinct response pattern was observed for each hormone analyzed, possibly related to specific negative feedback mechanisms and/or this species glucocorticoid-resistance. The use of this small neotropical primate may thus provide a unique opportunity to investigate cocaine-induced neuroendocrine effects.