Involvement of extracellular calcium and arachidonate in [3H] dopamine release from rat tuberoinfundibular neurons.
The mechanism of [3H]dopamine [( 3H]DA) release was investigated using primary cultures of dispersed cells from the rat tuberoinfundibular region, which contains tyrosine hydroxylase (TH)-like immunoreactive neurons. The calcium ionophore A23187 at 10 nM and above caused a significant and dose-dependent increase in [3H]DA release. In the presence of 50 microM A23187, [3H]DA release was detectable within 30 s and reached a plateau in 15 min. The induction of [3H]DA release by 50 microM A23187 was abolished by lowering the extracellular calcium concentration with 2 mM EDTA. Maitotoxin, another calcium-channel activator, also increased [3H]DA release at a concentration of 50 ng/ml. Exogenous additions of 100 mIU/ml phospholipase A2 and 10 microM arachidonate caused significant release of [3H]DA. Furthermore, A23187 stimulated [3H]arachidonate release from tuberoinfundibular dopaminergic (TIDA) neurons in a dose- and time-dependent manner. These results suggest that extracellular calcium and arachidonate are involved in the process of [3H]DA release from rat TIDA neurons.
Ohmichi
M
M
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
Hirota
K
K
Koike
K
K
Kadowaki
K
K
Miyake
A
A
Kiyama
H
H
Tohyama
M
M
Tanizawa
O
O
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D004298:Dopamine / Q000493:pharmacokinetics*; D005260:Female; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010740:Phospholipases / Q000502:physiology*; D010741:Phospholipases A / Q000494:pharmacology / Q000502:physiology*; D054467:Phospholipases A2; D051381:Rats; D011919:Rats, Inbred Strains; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D001095:Arachidonic Acids; D016718:Arachidonic Acid; D000001:Calcimycin; D014446:Tyrosine 3-Monooxygenase; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium; D004298:Dopamine