Influência do estresse em diferentes períodos iniciais da vida sobre o desenvolvimento de ansiedade e preferência por morfina em ratos

Abstract

Drug addiction has exerted a considerable impact on society, resulting in one of the biggest public health problems reaching different ethnic groups and social classes worldwide. Brazil is the largest consumer of opioid analgesics in South America, presenting, from a clinical point of view, a problematic situation, because the continuous administration could lead to tolerance and dependence. In this sense, the conditioned preference place protocol (CPP) has been widely used to evaluate the addition related to drug abuse. According to the World Health Organization (2010), stress is recognized by its chronicity, being identified as the evil of the XXI century. Its effects are directly related to the quality of life of the individual, family and society. This study was performed to evaluate the influence of stress exposure in different early life periods (fetal and neonatal) on anxiety-like symptoms and emotionality, and its consequences on addiction parameters after young animals' exposure to morphine. Animals exposed to post-NS showed lesser anxiety in different behavioral paradigms as well as increased exploratory behavior, and no preference for morphine in CPP. In contrast, animals exposed to pre-NS showed increased corticosterone plasma levels together with anxiety symptoms and greater preference for morphine following three days of drug withdrawal. Our findings indicate that the prenatal period is critical for stress, whose effects may be manifest throughout life. Although data demonstrate that the post -NS can develop chronic stress or adverse experiences, we can see from our results that the post -NS can trigger neuroadaptations able to overcome emotional consequences of early life. We hypothesized that pre-NS is able to modify responses to opioids along adulthood, which may facilitate development of addiction to these drugs.