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

• The lateral hypothalamus supports strong intracranial self-stimulation.
• A quantitative autoradiographic Mu and DA receptor analysis was applied after ICSS.
• Ventral Pallidum, Acb-Shell and Caudate–Putamen nuclei (among others) were involved.
• D1 but not D2 or mu receptors were activated after ICSS.
• These results were interpreted in terms of a goal-directed function of ICSS-LH.

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 mu-opioid 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.