Análise comparativa entre os efeitos da exposição à nicotina e retirada na adolescência ou na vida adulta sobre os comportamentos associados à ansiedade, a atividade locomotora e a função adrena de camundongos machos e fêmeas

Abstract

The tobacco epidemic is the single most preventable cause of death in the world and tobacco use is a risk factor for a number of diseases. WHO estimates that one-third of the adult population, 1 billion and 200 million, people are smokers. Adolescence is a critical period of vulnerability to smoking initiation and most adult smokers began smoking during adolescence. The aim of the present work is to study the behaviors associated with anxiety and locomotion activity, as well as adrenal function, in animals exposed to nicotine during adolescence or adult age and subsequently periods of withdrawal. This study used 462 adolescents and adults Swiss mice of both sexes. The animals were exposed (orally) to a nicotine (50μg/ml NIC e 2% - SAC) solution or a saccharine (2% - SAC) solution from the 30th postnatal day (PN) to PN45 during adolescence, or PN75 to PN91 for adult age. The animals were tested in the elevated plus maze (EPM) during exposure (PN45; PN90), 5 days withdrawal (PN50; PN95) and 10 days withdrawal (PN55; PN100). For Open Filed (OF) animals were tested during exposure (PN46; PN91), 5 days withdrawal (PN51; PN96) and 10 days withdrawal (PN56; PN101). The animals were tested in the EPM for 5 min and, in the next day, they were tested for 5 min on the OF. The tissue samples were collected 2h later the OF test (after the animals sacrifice). The tissue samples collected were: left adrenal gland for the analysis of catecholamine content; right adrenal gland for the analysis of tyrosine hidroxilase expression; serum for the analysis of cotinine and corticosterone concentration. To analyze only the nicotine effects a group of animals were not subjected to behavioral tests. Our results show that by during exposure or withdrawal period no differences were observed between groups regarding behaviors associated with anxiety in the EPM. In the OF, the NIC group during 10 days withdrawal presented a higher time in center during adolescence. For adults, females NIC showed a higher time in center. Regarding time in the corner, NIC group presented a higher time than SAC group at adolescence. For adults, at 10 days withdrawal period, NIC group showed fewer entries in center. Besides, female NIC group presented a higher number of entries in the corner. At adolescence, NIC group showed higher locomotion activity. Regarding the endocrine system, the catecholamine content was higher in NIC male group in adults. The corticosterone levels were affect by nicotine exposure besides the tyrosine hidroxilase expression was reduced in male NIC group at adulthood. Our study indicates that, behavioral as well as endocrine parameters were affected in our model of nicotine exposure during adolescence or adult and different withdrawal periods.