Effects of beta-phenylethylamine on dopaminergic neurons of the ventral tegmental area in the rat: a combined electrophysiological and microdialysis study.
The effects of systemic administration of beta-phenylethylamine (beta-PEA) and microiontophoretically applied beta-PEA on the spontaneous discharge of dopamine (DA) neurons in the ventral tegmental area (VTA) of the anesthetized rat were examined. Intravenous administration of beta-PEA (1.0, 2.5, and 5.0 mg/kg) and microiontophoretic applications of beta-PEA caused inhibitory responses in DA neurons. Systemic administration and microiontophoretic applications of beta-PEA induced dose- or current-dependent responses. The systemic beta-PEA-induced inhibitory responses were reversed by pretreatment with the DA D(2) receptor antagonists haloperidol (0.5 mg/kg i.p.) and sulpiride (10 mg/kg i.p). Pretreatment with reserpine (5 mg/kg i.p. 24 h earlier) did not completely block the systemic administration of beta-PEA (2.5 mg/kg) inhibition. A microdialysis study of freely moving rats demonstrated that the extracellular DA level increased significantly in response to local application of beta-PEA (100 muM) in the VTA via a microdialysis probe, and local application of beta-PEA-stimulated somatodendritic DA release in the VTA. The beta-PEA-induced release of DA was calcium ion-independent and was enhanced by pretreatment with pertussis toxin. These findings indicate that beta-phenylethylamine inhibits DA neuron activity via DA D(2) autoreceptors in the rat VTA and that this inhibitory effect is mediated by the somatodendritic DA release.
Ishida
Kota
K
Department of Neuroscience, Showa Pharmaceutical University, 3-3165, Higashitamagawagakuen, Machida, Tokyo 194-8543, Japan.
Murata
Mikio
M
Katagiri
Nobuyuki
N
Ishikawa
Masago
M
Abe
Kenji
K
Kato
Masatoshi
M
Utsunomiya
Iku
I
Taguchi
Kyoji
K
D000818:Animals; D002118:Calcium / Q000502:physiology; D004298:Dopamine / Q000502:physiology*; D004594:Electrophysiology; D007478:Iontophoresis; D008297:Male; D017551:Microdialysis; D009474:Neurons / Q000187:drug effects*; D010627:Phenethylamines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017557:Ventral Tegmental Area / Q000166:cytology / Q000187:drug effects*
D010627:Phenethylamines; C029261:phenethylamine; D002118:Calcium; D004298:Dopamine