Regulators of G- Protein Signalling : Evidence That RGS 4 Expression Is Affected by Altered States of Dopamine Neurotransmission
Volk, Michael L.
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In order to develop a convenient model for the study of RGSs, this experiment looked at the role they play in the dopamine (DA) system and the areas of the brain innervated by dopamine cells in rats. The DA system has been extensively studied, with very well characterized changes in sensitivity under varying conditions (Personal Com., Bannon). That is to say, it is extremely adaptive, and therefore is an excellent model system for the study of a signal regulator. There are two major efferent dopaminergic projections, and these are located in the midbrain and classified as the mesostriatal and mesolimbocortical systems. The mesostriatal system projects from the substantia nigra and the ventral tegmentum via the medial forebrain bundle to the caudate putamen area (nucleus caudatus). This projection plays an important role in the control of movement initiation and posture, and the degeneration of the mesostriatal dopamine neurons results in the motor disorders present in Parkinson's disease (Kandel et al., 1991). The mesolimbocortical system projects from the ventral tegmentum to the limbic (i.e. nucleus accumbens) and cortical (i.e. prefrontal cortex) areas.