Dopamine and 7-OH-DPAT may act on D(3) receptors to inhibit tuberoinfundibular dopaminergic neurons

Whether the tuberoinfundibular dopaminergic (TIDA) neurons resided in the dorsomedial arcuate nucleus (dmARN) can respond to dopamine and a dopamine D(3) receptor agonist, 7-hydroxydipropylaminotetralin (7-OH-DPAT), was the focus of this study. In studies using extracellular single-unit recording of...

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Bibliographic Details
Published in:Brain research bulletin 2000-08, Vol.52 (6), p.567-572
Main Authors: Lin, J Y, Yen, S H, Shieh, K R, Liang, S L, Pan, J T
Format: Article
Language:English
Subjects:
Animals
Arcuate Nucleus of Hypothalamus - cytology
Arcuate Nucleus of Hypothalamus - drug effects
Arcuate Nucleus of Hypothalamus - metabolism
Dopamine - metabolism
Dopamine - pharmacology
Dopamine Agonists - pharmacology
Female
Hypothalamo-Hypophyseal System - cytology
Hypothalamo-Hypophyseal System - drug effects
Hypothalamo-Hypophyseal System - metabolism
Neurons - cytology
Neurons - drug effects
Neurons - metabolism
Rats
Rats, Sprague-Dawley
Receptors, Dopamine D2 - drug effects
Receptors, Dopamine D2 - metabolism
Receptors, Dopamine D3
Tetrahydronaphthalenes - pharmacology
Tuber Cinereum - cytology
Tuber Cinereum - drug effects
Tuber Cinereum - metabolism
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Summary:Whether the tuberoinfundibular dopaminergic (TIDA) neurons resided in the dorsomedial arcuate nucleus (dmARN) can respond to dopamine and a dopamine D(3) receptor agonist, 7-hydroxydipropylaminotetralin (7-OH-DPAT), was the focus of this study. In studies using extracellular single-unit recording of dmARN neurons in brain slices obtained from ovariectomized rats, dopamine and 7-OH-DPAT inhibited 60.1% (n = 141) and 80.9% (n = 47) of recorded dmARN neurons, respectively. Other dopamine D(1) or D(2) receptor agonists were not as effective. Intracerebroventricular injection of 7-OH-DPAT (10(-9) mol/3 microl) in ovariectomized, estrogen-primed rats significantly lowered the TIDA neuronal activity as determined by 3, 4-dihydroxyphenylacetic acid (DOPAC) levels in the median eminence. Co-administration of a putative D(3) receptor antagonist, U-99194A, could prevent the effect of 7-OH-DPAT. Unilateral microinjection of 7-OH-DPAT or dopamine itself (10(-11)-10(-9) mol/0.2 microl) into the right dmARN exhibited the same inhibitory effect on TIDA neurons. In all, dopamine may act on D(3) receptors to exhibit an inhibitory effect on its own release from the TIDA neurons.
ISSN:0361-9230