An outline of the ascending bioaminergic tracts involved in hypothalamopituitary function in the rat.
Dopaminergic fibres comprise one group whose origin is in the substantia nigra in the midbrain and project to the basal ganglia (forming part of the extrapyramidal motorsystem). An intrinsic tuberoinfundibular system is responsible for dopaminesecretion into the hypophysial-portal vascular system, which tonically inhibits prolactin secretion. The mesolimbic dopamine system that enervates brain structures involved in affective states is not shown. Ascending fibres from the locus cenuleus bring noradrenergic influences the hypothalamus, and fibres from the raphe nuclei can y serotoninergic signals into the hypothalamus and elsewhere. All of these pathways are involved in the regulation of the anterior and posterior pituitary and, in addition, have important effects on visceral function and behaviour. Modified from Martin et al (1977); by courtesy of FA Davis Company.
