Drug Behavior and Blood Brain Barrier Permeability Essay

Drug Behavior and Blood Brain Barrier Permeability - Essay Example Adolescent's innovation and curiosity can be transformed in dependence and addiction. Substance abuse is a maladaptive pattern leading to clinically significant impairment or distress. Several illicit substances produce dependence, defined as substance abuse that leads to loss of control, monopolization of time by substance use, and adverse medical, social, or emotional consequences that include tolerance and withdrawal (Gonzalez-Mayo, et al., 2005). There is a continued use in spite of knowing the problems that it causes. The mesolimbic dopamine system, particularly the nucleus accumbens, is a critical reinforcing site for drug addiction; this same pathway is believed to control drug craving and seeking behavior. It was recently proposed that addiction is a disease of learning and memory; classical conditioning describes learning in which a natural response is elicited by a conditioned, or learned, stimulus that previously was presented in conjunction with an unconditioned stimulus. Some evidence suggests that the mechanisms involved in the acute stimulant effects of cocaine and other illicit psychostimulants may be similar to the underlying features that explain chronic effects and addiction. The studies conducted in mice have allowed researchers to disclose important data regarding addiction pathways and neurotransmitter input. In humans, cocaine acute intoxication ca... On the other hand, ethanol intoxication causes disinhibition, emotional lability, slurred speech, ataxia, coma, and blackouts. Nicotine is one of the most addictive substances, and causes restlessness, insomnia, anxiety, and arrhythmias. Boudreau & Wolf (2005) define sensitization as "the augmentation of behavioral responses to drugs of abuse that occurs during their repeated administration and persists long after drug exposure is discontinued". The study conducted by Bainton, et al. is based on behavioral sensitization and the similarities between the addiction pathways of mammals and flies. By analyzing genetic features of Drosophila, the authors show that the behavioral defects observed in the mutant strains are not caused by accessibility changes of the administered drugs, but from alterations in the blood brain barrier, by means of changes in nervous system function. The Experimental Fly Since 1900, Drosophila flies have been used for genetic experiments. The fruit fly Drosophila melanogaster is highly accessible to genetic analyses, and has been introduced as a novel model organism to help interpret the complex foundation of drug-induced behaviors (Heberlein, 2008). In this study, flies were maintained on special agars and mutants where screened for drug sensitivity. First, researchers evaluated several fly strains that carried a mutation named EP1529, and found an increased sensitivity to both cocaine and nicotine exposures; excision of the mutation restored drug sensitivity in these flies. Additionally, the altered gene was identified as moody, which encode for a G protein-coupled receptor. In both larvae and adult flies,