Opioidergic modulation of behavioral selection during lactation / Modulação opioidérgica na seleção comportamental após o parto

AUTOR(ES)

Aline de Mello Cruz

DATA DE PUBLICAÇÃO

2009

RESUMO

Treatment of postpartum female rats with morphine inhibits maternal behavior. The same treatment also stimulates foraging in adult animals. Exposure to drugs of abuse may result in a progressive and enduring enhancement of their reinforcing effects. Puerperal treatment with morphine leads to reverse tolerance to this drug, ultimately influencing the effects of opiates on maternal behavior. The aim of the present study was to investigate whether abrupt withdrawal from repeated morphine treatment during late pregnancy may influence the effects of morphine on behavioral selection in lactating rats. Animals were exposed simultaneously to pups and insects, and the choice between taking care of the pups and hunting for insects was observed. Female Wistar rats were treated with morphine (3.5 mg/kg/day, subcutaneous [s.c.]) or saline for 5 days beginning on pregnancy day 17. On day 5 of lactation, animals were acutely challenged with morphine (0.5, 1.0, or 1.5 mg/kg, s.c.; MM0.5, MM1.0, and MM1.5 groups, respectively) or saline (MS group) and simultaneously tested for predatory hunting and maternal behavior. Control groups were pretreated with saline and challenged with morphine (SM0.5, SM1.0, and SM1.5 groups) or saline (SS group). Animals treated with morphine during late pregnancy and acutely challenged with 1.0 mg/kg morphine (MM1.0 group) exhibited significantly decreased maternal behavior and enhanced hunting. This effect was not evident for the 0.5 mg/kg dose. The 1.5 mg/kg morphine dose decreased maternal behavior and increased hunting in both the MM1.5 group and in animals acutely challenged with morphine after previous saline treatment (SM1.5 group). These results provide evidence of plasticity of the opioidergic role in behavioral selection during lactation.

ASSUNTO(S)

morphine forrageamento periaqueductal gray abuso de drogas substância cinzenta periaquedutal morfina opioid opióide foraging drug abuse

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