Persistent and delayed behavioral changes after nicotine treatment in adolescent rats

Smoking and consumption of alcoholic beverages are frequently associated during adolescence. This association could be explained by the cumulative behavioral effects of nicotine and ethanol, particularly those related to anxiety levels. However, despite epidemiological findings, there have been few animal studies of the basic neurobiology of the combined exposure in the adolescent brain. In the present work we assessed, through the use of the elevated plus maze, the short-and long-term anxiety effects of nicotine (NIC) and/or ethanol (ETOH) exposure during adolescence (from the 30th to the 45th postnatal day) in four groups of male and female C57BL/6 mice: (1) Concomitant NIC (nicotine free-base solution (50 mg/ml) in 2% saccharin to drink) and ETOH (ethanol solution (25%, 2 g/kg) i.p. injected every other day) exposure; (2) NIC exposure; (3) ETOH exposure; (4) Vehicle. C57BL/6 mice were selected, in spite of the fact that they present slower ethanol metabolism, because they readily consume nicotine in the concentration used in the present study. During exposure (45th postnatal day: PN45), our results indicated that ethanol was anxiolytic in adolescent mice and that nicotine reverted this effect. Short-term drug withdrawal (PN50) elicited sex-dependent effects: exposure to nicotine and/or ethanol was anxiogenic only for females. Although neither nicotine nor ethanol effects persisted up to 1 month postexposure (PN75), the coadministration elicited an anxiogenic response. In spite of the fact that generalizations based on the results from a single strain of mice are prone to shortcomings, our results suggest that the deficient response to the anxiolytic effects of ethanol in adolescents co-exposed to nicotine may drive higher ethanol consumption. Additionally, increased anxiety during long-term smoking and drinking withdrawal may facilitate relapse to drug use.

Section: Anxiogenic Effects During Withdrawalsupporting

confidence: 92%

Combined Exposure to Nicotine and Ethanol in Adolescent Mice Differentially Affects Anxiety Levels during Exposure, Short-Term, and Long-Term Withdrawal

Abreu‐Villaça

Nunes

Queiroz-Gomes

et al. 2007

“…Depending on age (early vs late adolescence) (Belluzzi et al, 2004) and dose (Vastola et al, 2002;Belluzzi et al, 2004), adolescents show either enhanced or reduced conditioned place preference. In addition, sensitivity to the somatic aspects of nicotine withdrawal is decreased in adolescents (O'Dell et al, 2004) and persistent reductions in motor activity are still observed 2-6 weeks after withdrawal (Trauth et al, 2000a;Slawecki and Ehlers, 2002). These data, demonstrating the unique characteristics of the adolescent behavioral response to nicotine, underscore the importance of understanding nicotine SA during adolescence.…”

Section: Introductionmentioning

confidence: 74%

Acquisition of Nicotine Self-Administration in Adolescent Rats Given Prolonged Access to the Drug

Chen

Matta

Sharp

2006

105

As most human tobacco use begins during adolescence and ongoing development of the adolescent central nervous system could affect acquisition of nicotine self-administration (SA), our established rat SA procedure was modified to study adolescent acquisition of SA with prolonged access to nicotine (23 h/day). Postnatal age 43-45 female Lewis rats, without prior shaping, conditioning, or food deprivation, were housed in operant chambers equipped with two levers; pressing the active lever triggered an i.v. injection of nicotine. By the 10th day of SA, rats receiving 7.5, 15, 30, or 60 mg/kg/injection nicotine (free base) obtained 23716, 5078, 6578, or 4875 injections (mean7SE), respectively. In the 30 mg/kg/injection group, active : inactive ratio was greater than 2 after SA day 4; 92% of injections occurred during the 12-h active (dark) phase of the light cycle. Main effects (analysis of variance) were shown for day and lever (ie active vs inactive) (po0.001). Adolescent males showed similar dose-dependent nicotine SA. With the increasing workload imposed by raising the fixed ratio (FR), less nicotine was self-administered at FR 5 and 7 compared to FR 1 and 3. In comparison to adult females selfadministering 30 mg/kg/injection of nicotine at FR 1, adolescents acquired nicotine SA at an accelerated rate (po0.05) and received a greater number of injections (po0.05) by day 10. In conclusion, when given prolonged access to the drug, both female and male adolescent Lewis rats rapidly acquire nicotine SA within the dosage range and FR constraints previously observed in adult Lewis rats. However, adolescent females acquired the behavior more rapidly and attained higher levels of stable nicotine SA than adults.

“…Previous work in rats has shown that adolescent nicotine, followed by 2-5 weeks of abstinence, has long-term effects on behavior in both the emotional and motivational domain, exemplified by an increase in novelty-induced activity, elevated anxiety, higher levels of passive avoidance, and enhanced vulnerability to nicotine self-administration (Adriani et al, 2006(Adriani et al, , 2003Slawecki et al, 2005;Trauth et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Long-Lasting Cognitive Deficits Resulting from Adolescent Nicotine Exposure in Rats

Counotte

Spijker

Burgwal

et al. 2008

151

134

Adolescence is a developmental period, during which the brain and particularly medial prefrontal cortical (mPFC) regions thereof have not fully matured. Because epidemiological data have suggested that adolescent nicotine use may result in disturbances in cognitive function in adulthood, we investigated the long-term effects of adolescent nicotine exposure in rats. Male Wistar rats were exposed to either nicotine (three times daily, 0.4 mg/kg s.c.) or saline for 10 days during (postnatal day (PND) 34-43) or following (PND 60-69) adolescence. After 5 weeks during adulthood, separate groups of animals were tested in operant paradigms taxing attention and distinct measures of impulsivity. Visuospatial attention and impulsive action were tested in the five-choice serial reaction time task, whereas impulsive choice was assessed in the delayed reward task. Our data show that adolescent, but not postadolescent, nicotine exposure affects cognitive performance in adulthood and results in diminished attentional performance and increments in impulsive action, while leaving impulsive choice intact. This altered cognitive performance appeared to be associated with enhanced releasability of dopamine in the mPFC. Together, these data suggest that adolescence is a time window during which the brain is vulnerable to long-lasting cognitive disturbances resulting from nicotine exposure.