Changes in D1 but not D2 dopamine or mu-opioid receptor expression 4 in limbic and motor structures after lateral hypothalamus electrical 5 self-stimulation: A quantitative autoradiographic study

Abstract

Intracranial self-stimulation (ICSS) of the lateral hypothalamus (LH) is involved in the activation of neuroanatomical systems that are also associated with the processing of natural and other artificial rewarding stimuli. Specific components of this behavior (hedonic impact, learning, and motor behavior) may involve changes in different neurotransmitters, such as dopamine and opioids. In this study, quantitative autoradiography was used to examine changes in muopioid and D1/D2-dopamine receptor expression in various anatomical regions related to the motor and mesolimbic reward systems after intracranial self-stimulation of the LH. Results of the behavioral procedure and subsequent radiochemical assays show selective changes in D1 but not D2 or mu receptors in Accumbens-Shell, Ventral Pallidum, Caudate–Putamen, and Medial Globus Pallidus. These findings are discussed in relation to the different psychobiological components of the appetitive motivational system, identifying some dissociation among them, particularly with respect to the involvement of the D1-dopamine subsystem (but not D2 or mu receptors) in goal-directed behaviors.