The Influence of N6-cyclopentyladenosine and Magnesium on Norepinephrine Release in the Rat Hippocampus

• 영문명: The Influence of N⁶-cyclopentyladenosine and Magnesium on Norepinephrine Release in the Rat Hippocampus
• 발행기관: 대한생리학회-대한약리학회
• 저자명: Yeung Bong Park,Sang Duk Park Bong Kyu Choi
• 간행물 정보: 『The Korean Journal of Physiology & Pharmacology』제1권 제2호, 135~142쪽, 전체 8쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 1997.01.01

영문 초록

As it has been reported that the depolarization-induced norepinephrine (NE) release is modulated by activation of presynaptic A₁-adenosine heteroreceptor and various lines of evidence indicate that A₂-adenosine receptor also presents in hippocampus, and that the adenosine effect is magnesium dependent, the present study was undertaken to delineate the role of adenosine receptors in the modulation of hippocampal NE release. Slices from the rat hippocampus were equilibrated with [³H]-NE and the release of the labelled product, [³H]-NE, was evoked by electrical stimulation (3 Hz, 5 V cm^-1, 2 ms, rectangular pulses), and the influence of various agents on the evoked tritium outflow was investigated. N⁶-cyclopentyladenosine (CPA), in concentrations ranging from 0.1 to 10 ㄍM, decreased the [³H]-NE release in a dose-dependent manner without changing the basal rate of release, and these effects were significantly inhibited by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 2 ㄍM) treatment. When the magnesium concentration was reduced to 0.4 mM or completely removed, the evoked NE release increased along with decreased basal rate of release. In contrast, increasing the magnesium concentrations to 2.4 and 4 mM, decreased the evoked NE release. The CPA effects on evoked NE release were reduced by magnesium removal, but potentiated by 2.4 mM magnesium in the medium. 5-(N-cyclopropyl)-carboxamodiadenosine (CPCA, 1 & 10 ㄍM), an A₂-agonist, decreased the evoked tritium outflow, and this effect was also abolished by DPCPX pretreatment. CGS, a powerful A₂-agonist, did not affect the evoked NE release. However, the effects of CPCA and CGS on evoked NE release were significantly increased by pretreatment of DPCPX in the magnesium-free medium. These results indicate that inhibitory effect of A₁-adenosine receptor on NE release is magnesium-dependent, and A₂-receptor may be present in the rat hippocampus.

키워드

N⁶-cyclopentyladenosine Magnesium Norepinephrine Hippocampus