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Stress, prolactin and hypothalamic dopaminergic neurons
K E Moore1, K T Demarest, K J Lookingland
1Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824.
Neuropharmacology
|July 1, 1987
Summary
Dopamine (DA) neurons in the hypothalamus (tuberoinfundibular system) differ significantly from those in the nigrostriatal system. Tuberoinfundibular DA neurons are stimulated by prolactin and show sexual dimorphism.
Area of Science:
- Neuroscience
- Endocrinology
- Neurochemistry
Background:
- Dopamine (DA) neurons are crucial in brain function, with the nigrostriatal system being extensively studied.
- However, the nigrostriatal DA system may not represent all DA neurons, necessitating research into other systems like the tuberoinfundibular DA system.
Purpose of the Study:
- To compare the distinct properties of nigrostriatal DA neurons with hypothalamic tuberoinfundibular DA neurons.
- To elucidate the unique regulatory mechanisms and characteristics of tuberoinfundibular DA neurons.
Main Methods:
- Biochemical estimation of DA neuron activity, including synthesis, turnover, and metabolism.
- Measurement of DOPA accumulation, DA decline, and dihydroxyphenylacetic acid concentrations in specific brain regions (striatum and median eminence).
Main Results:
- Tuberoinfundibular DA neurons are not directly regulated by DA receptor-mediated mechanisms.
- These neurons are stimulated by prolactin and exhibit a 2-3 fold higher activity in females compared to males.
- Activity is inhibited by neuronal circuits activated by suckling and restraint stress.
Conclusions:
- Tuberoinfundibular DA neurons possess unique regulatory properties distinct from nigrostriatal DA neurons.
- Prolactin stimulation, sexual dimorphism, and stress/suckling-induced inhibition are key characteristics of the tuberoinfundibular DA system.