Histamine-induced cyclic AMP accumulation in type-1 and type-2 astrocytes in primary culture.
Histamine-induced cyclic AMP (cAMP) accumulation was studied in purified primary cultures of type-1 and type-2 astrocytes from neonatal rat brain. Histamine induced remarkable cAMP accumulation in type-1 astrocytes in a dose-dependent manner (EC50 = 1.2 x 10(-5) M, Emax = 1100% of control). In contrast, histamine had no significant effect on cAMP accumulation in type-2 astrocytes. Famotidine, an H2-antagonist, dose-dependently inhibited histamine-induced cAMP accumulation in type-1 astrocytes (Ki = 3 x 10(-8) M), but mepyramine (10(-6) M), an H1-antagonist, had no effect. Dimaprit and impromidine, H2-agonists, stimulated cAMP accumulation, but 2-pyridylethylamine, an H1-agonist, did not stimulate it nor augment the H2-agonist-induced cAMP accumulation. These results indicate that (1) histamine induces cAMP accumulation in type-1 astrocytes but not in type-2 astrocytes, and that (2) histamine-induced cAMP accumulation in type-1 astrocytes is mediated by H2-receptors without significant augmentation via H1-receptors.
Kubo
A
A
Department of Pharmacology II, Faculty of Medicine, Osaka University, Suita, Japan.
Fukui
H
H
Inagaki
N
N
Kanamura
A
A
Wada
H
H
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D015738:Famotidine / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology*; D007700:Kinetics; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011970:Receptors, Histamine H2 / Q000502:physiology; D013268:Stimulation, Chemical
D011970:Receptors, Histamine H2; D015738:Famotidine; D006632:Histamine; D000242:Cyclic AMP; D011738:Pyrilamine