Perinatal undernutrition facilitates morphine sensitization and cross-sensitization to cocaine in adult rats: a behavioral and neurochemical study

VELÁZQUEZ EE, VALDOMERO A, ORSINGHER O., CUADRA G.

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2010 vol. 165 p. 475 - 475

he development of sensitization to the locomotor effects of morphine and cross-sensitization between morphine and cocaine were evaluated in adult rats submitted toa protein malnutrition schedule from the 14th day of gestation up to 30 days of age (D-rats), and compared with wellnourished animals (C-rats). Dose-response curves to morphine-induced locomotor activity (5, 7.5, 10 or 15 mg/kg, i.p., every other day for 5 days) revealed a shift to the left in D-rats compared to C-rats. This implies that D-rats showed behavioral sensitization to the lower dose of morphine used (5mg/kg), which was ineffective in C-rats. Furthermore, when a cocaine challenge (10 mg/kg, i.p) was given 48 h after the last morphine administration, only D-rats exhibited cross-sensitization in morphine-pretreated animals (7.5 and 10 mg/kg). In order to correlate the differential response observed with the functioning of the mesocorticolimbic dopaminergic system, extracellular dopamine (DA) levels were measured in t