s / Drug and Alcohol Dependence 140 (2014) e2–e85 e27 from the International Affective Picture System. The data were modeled using standard voxel-based methods. The BOLD response to positive and negative images (relative to neutral) was compared between groups with respect to gender. Results: Cocaine users had less activation inmesolimbic regions than controls in response to positive and negative images. Among the men, there were no significant differences between cocaine users and controls when viewing positive pictures. When viewing negative pictures, cocaine-dependent men had significantly less activity in the posterior cingulate than control men. Among the females however, both positive and negative images evoked a significantly lowerBOLDresponse in themedialprefrontal cortex from the cocaine users relative to the controls. Conclusions: These results demonstrate that while cocaine using males differ from controls only in response to negative images, the female cocaine users have a blunted response in the frontal cortex to emotional stimuli independent of valence. This may be associated with a stronger relationship betweenmood and drug use behavior in female than males. While many studies in the substance dependence literature involve primarily men, these data highlight the need to consider gender in future behavioral and cognitive treatment approaches among cocaine users. Financial support: K01DA027756, 5T32DA007288. http://dx.doi.org/10.1016/j.drugalcdep.2014.02.094 Comparison of sentenced inmates’ drug use patterns before and during incarceration Glorimar Caraballo-Correa, R. Ramirez, J.J. Ruiz, C.E. Albizu-Garcia Center for Evaluation and Sociomedical Center, University of Puerto Rico, San Juan, United States Aims: Drug users are over represented in correctional settings and drug use in prison is a worldwide phenomenon, yet little is known about patterns in drug use as individuals transition from community to prison and their implications for services planning. We report results of a study that compared drug use patterns prior and during imprisonment in a representative sample of the sentenced inmate population in the Puerto Rico prison system. Methods: 1179 inmates (89.7% response rate) participated in a structured questionnaire administered through 2 interview modalities: Computer Assisted Personal Interview for social and health variables; Audio Computer Assisted Self Interview for sensitive information. A latent transition analysis was conducted with MPLUS using as class indicators variables representing 6 types of illegal drug use before and during the current incarceration. The model assumed measurement invariance of the classes obtained before and during incarceration. Results: A 3 class solution was chosen based on good model classification accuracy (entropy .85). Before incarceration: Class 1: inmates with low probability of using any drug (23%), Class 2: inmates with a pattern of using all drugs with a moderate-high probability (31%), Class 3: inmates with a high use of marihuana and low-moderate use of cocaine and non-prescribed medications (45%). Drug use patterns during imprisonment: 55% of those in the highdruguse class before incarceration remained in the same class. 33% transitioned to the low drug use class and 14% to the class that mainly uses marihuana. 1% of those in the class with low probability of drug use transitioned to the class of heavy drug use. 7% of thosewhomainlyusedmarihuanaandnon-prescribedmedications transitioned to the heavy drug use class. Conclusions: These findings should inform prevention interventions. Half of the inmates persist in their drug use once in prison and 8% transitioned from soft to hard drugs with serious public health implications given the frequency of injection drug use in this context. Financial support: NIDA Grant # 2R24DA024868-03. http://dx.doi.org/10.1016/j.drugalcdep.2014.02.095 The role of serotonin 2A and 2C receptors in tryptamine hallucinogens N,N-dimethyltryptamine and N,N-diisopropyltryptamine Theresa Carbonaro1,2, M.J. Forster1, Michael B. Gatch1 1 Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States 2 Center for Addiction Research, University of Texas Medical Branch, Galveston, TX, United States Aims: Hallucinogens have beenused for centuries yet compared to other drug classes, relatively little is known about their mechanism of action. Classic hallucinogens are grouped into tryptamine, phenethylamine and ergot alkaloid classes of hallucinogens. Serotonin (5-HT) 2A and 2C receptors are primary targets for classic serotonin-mediated hallucinogens and presumed to be targets for the two tryptamine hallucinogens N,N-dimethyltryptamine (DMT; visual hallucinations) and N,N-diisopropyltryptamine (DiPT; auditory distortions). The roles of these receptors in attenuating the effects DMT and DiPT were assessed. Methods: Drug discrimination, head twitch and radioligand binding assayswereused. Ratswere trained todiscriminateDMTor DiPT from saline. Antagonists selective for 5-HT2AR (MDL100907) and5-HT2CR (SB242084)wereused toattenuate thediscriminative stimulus effects. MDL100907 was used to attenuate drug-induced head twitches in mice. Radioligand binding was performed at the 5-HT2CR in HEK cells for DiPT and compared to pre-existing data for DMT. Results: MDL100907 fully blocked the discriminative stimulus effects of DMT, but only partially blocked DiPT. SB242084 partially attenuated the discriminative stimulus effects of DiPT, but minimally attenuated DMT’s effects. Both compounds produced head twitches (DiPT>DMT), which were blocked by MDL1000907. DiPT and DMT had similar binding and were fully efficacious at the 5HT2C receptor, but DiPT was ∼ 20 times less potent at stimulating IP-1 formation. Conclusions: 5-HT2AR and 5-HT2CR play different roles in mediating the discriminative stimulus effects of DMT and DiPT. 5HT2AR is essential for both compounds, whereas 5-HT2CR may be more important for the stimulus effects of DiPT. DMT has a pharmacological profile similar to other classical hallucinogens. Nodrug tested was able to completely block DiPT-like effects, suggesting other or multiple receptors may be important. Financial support:NBAT32AG020494andNIHN01DA-7-8872. http://dx.doi.org/10.1016/j.drugalcdep.2014.02.096