Neuroscience Online

Section I: Cellular and Molecular Neurobiology 12. Biogenic Amine Neurotransmitters Part 3 of 11 Jack C. Waymire, Ph.D.

Mesostriatal DA System - The mesostriatal DA system, referred to as the nigrostriatal pathway, is composed of two components, a dorsal mesostriatal pathway and a ventral mesostriatal pathway. These two pathways are important for movement control and reward mechanisms.

The dorsal mesostriatal pathway (blue) originates in the substantia nigra par compacta and ascends to innervate the corpus striatum (caudate, putamen, and globus palladous), where it modulates the output of the corpus striatum. The destruction of the nigrostriatal cells in Parkinson's disease produces marked motor deficits.

The ventral mesostriatal pathway (red) also originates in the substantia nigra but innervates the nucleus accumbens, olfactory tubercles and medial caudate-putamen. The ventral nigrostriatal pathway plays an important role in positive incentive characteristics of rewarding behaviors, as will be discussed further in Chapter 12, Part 10.

Mesolimbocortical DA System - The Mesolimbocortical DA system (purple) originates in the midbrain and projects to limbic structures (septum, amygdala, hippocampus, olfactory nucleus, and limbic cortex). This DA system is believed to participate in schizophrenia. (See Chapter 12, Part 11) The current hypothesis is that an increase in DA function in the mesolimbic system and a decreased function in the mesocortical DA systems occurs in schizophrenia.

Periventricular DA System - The periventricular DA system (orange in Fig. 12.3) coordinates motivated behavior. These DA cells originate in the periventricular region of hypothalamus and send short axons to several thalamic and hypothalamic nuclei. Collaterales also descend to the intermediolateral cell column of the spinal cord to synapse with sympathetic preganglionic neurons. This dual innervation of hypothalamic and sympathetic preganglionic neurons is believed to integrate the central and autonomic components of motivated behaviors, including behaviors such as sex, thirst and appetite.

Tuberohypophyseal DA System - The tuberohypophyseal DA system mediates the control of milk production during lactation. The DA cells (green) originate in the periventricular and arcuate nuclei of the hypothalamus and project to the median eminence of the hypothalamus where they release DA into the capillary plexus of the hypophyseal-portal system. DA travels to the anterior pituitary where it inhibits the release of prolactin, the hormone that stimulates milk production in lactating animals.

Cross Reference: Links for Dopamine