Regulation of glial Na+/K+-ATPase by serotonin: identification of participating receptors.
The purpose of the present study was the characterization of the receptors participating in the regulatory mechanism of glial Na+/K+-ATPase by serotonin (5-HT) in rat brain. The activity of the Na+ pump was measured in four brain regions after incubation with various concentrations of serotoninergic agonists or antagonists. A concentration-dependent increase in enzyme activity was observed with the 5-HT1A agonist R (+)-2-dipropylamino-8-hydroxy-1,2,3, 4-tetrahydronaphthalene hydrobromide (8-OH-DPAT) in homogenates or in glial membrane enriched fractions from cerebral cortex and in hippocampus. Spiperone, a 5-HT1A antagonist, completely inhibited the response to 8-OH-DPAT but had no effect on Na+/K+-ATPase activity in cerebellum where LSD, a 5-HT6 agonist, elicited a dose-dependent response similar to that of 5-HT. In brainstem, a lack of response to 5-HT and other agonists was confirmed. Altogether, these results show that serotonin modulates glial Na+/K+-ATPase activity in the brain, apparently not through only one type of 5-HT receptor. It seems that the receptor system involved is different according to the brain region. In cerebral cortex, the response seems to be mediated by 5-HT1A as well as in hippocampus but not in cerebellum where 5-HT6 appears as the receptor system involved.
Peña-Rangel
M T
MT
Facultad de Ciencias Naturales, U.A.Q., México, DF, México.
Mercado
R
R
Hernández-Rodríguez
J
J
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002531:Cerebellum / Q000201:enzymology; D002540:Cerebral Cortex / Q000201:enzymology; D000242:Cyclic AMP / Q000494:pharmacology; D006624:Hippocampus / Q000201:enzymology; D008238:Lysergic Acid Diethylamide / Q000494:pharmacology; D008297:Male; D009457:Neuroglia / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D010566:Virulence Factors, Bordetella; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D008238:Lysergic Acid Diethylamide; D000242:Cyclic AMP; D000254:Sodium-Potassium-Exchanging ATPase