Alexander Frid

Mohammad Helmy.GIF (25572 bytes)
Mohammad Helmy

Mohammad Helmy recalls that his favorite research experiences were when he and his faculty mentor performed statistical analyses of the data and brainstormed about an explanation for the results.  Mohammad says that research affected him to such an extent that he no longer accepts scientific "facts" without first questioning the metho-dology used in accumu-lating the data.  Mohammad recommends that undergraduate researchers realize at all times the contributions they are making to the community around them. triangle.gif (504 bytes)




Cocaine is believed to exert its reinforcing actions by indirectly increasing activation of postsynaptic dopamine (DA) receptors (divided into five subtypes, D1 to D5). We studied the role of the D1 receptor in reinforcement by examining the effects of the D1-antagonist SCH23390 and the D2-antagonist eticlopride on self-administration of the D1-agonist SKF82958. Rats were surgically implanted with an intravenous catheter, then allowed to self-administer cocaine during daily sessions until response rates stabilized. On subsequent test days, rats were allowed to self-administer SKF82958 alone or in combination with either SCH23390 or eticlopride. As the SCH23390 dose was increased, self-administration of the low dose of SKF82958 decreased; responses for the higher SKF82958 doses initially increased before eventually declining. Eticlopride caused a decrease in self-administration of the lower SKF82958 doses, but caused no change in self-administration of the higher doses. SCH23390 disrupted the highly regular response patterns that are indicative of reinforcement, while eticlopride had no effect on these response patterns.triangle.gif (504 bytes)

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Faculty Mentor                                                                                                                
James D Belluzzi.GIF (20285 bytes)

James Belluzzi

College of Medicine

The rewarding effects of cocaine have been traced mainly to its enhancement of brain dopamine (DA) systems. With five DA receptor subtypes (D1 to D5), it is important to determine which subtype is affected by cocaine.  This study replicated the finding that self-administration of D1-agonists produces well-timed, cocaine-like response patterns, and showed that D1-agonist self-administration is antagonized by blockade of D1 receptors, but largely unaffected by D2 blockade.  These results support a role for D1 receptors in reinforcement, and suggest that cocaine's actions involve stimulation of dopamine D1 receptors­a fact that might help elucidate the mechanism of action of this important drug.  More generally, UCI's undergraduate research program allows students to experience laboratory research in pursuit of scientific answers to real research questions.triangle.gif (504 bytes)

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Mohammad Helmy - Effects of the D1-Antagonist SCH23390... [1] [2] [3] [4] [5] [6]

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