P2Y receptor-mediated excitation in the posterior hypothalamus.
Histaminergic neurons located in the posterior hypothalamus (tuberomamillary nucleus, TMN) project widely through the whole brain controlling arousal and attention. They are tonically active during wakefulness but cease firing during sleep. As a homeostatic theory of sleep involves ATP depletion and adenosine accumulation in the brain, we investigated the role of ATP and its analogues as well as adenosine on neuronal activity in the TMN. We show increased firing of rat TMN neurons by ATP, ADP, UTP and 2meSATP, indicating activation of receptors belonging to the P2Y family. Adenosine affected neither membrane potential nor firing of these cells. Single-cell reverse transcriptase-polymerase chain reaction revealed that P2Y1 and P2Y4 are prevailing receptors in TMN neurons. P2Y1 receptor mRNA was detected with a higher frequency in 2-week-old than in 4-week-old rats; in accordance, 2meSATP was more potent than ATP. Semi-quantitative real-time polymerase chain reaction revealed a developmental downregulation of mRNA levels for P2Y1 and P2Y4 receptors. Immunocytochemistry demonstrated neuronal and glial localization of the P2Y1 receptor protein. Network activity measured with multielectrode arrays in primary cultures made from the posterior hypothalamus was enhanced by UTP and 2meSATP (P2Y4 and P2Y1 agonists, respectively). ATP caused an inhibition of firing, which was reversed in the presence of suramin or gabazine [gamma-aminobutyric acid (GABA)A receptor antagonist], indicating that GABAergic neurons are preferentially activated by ATP in this network. Excitation of the wake-active TMN neurons by nucleotides and the lack of adenosine action may be important factors in sleep-wake regulation.
Sergeeva
Olga A
OA
Department of Neurophysiology, Heinrich-Heine-Universität, POB 101007, D-40001 Düsseldorf, Germany. olga.sergeeva@uni-duesseldorf.de
Klyuch
Boris P
BP
Fleischer
Wiebke
W
Eriksson
Krister S
KS
Korotkova
Tatiana M
TM
Siebler
Mario
M
Haas
Helmut L
HL
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000227:Adenine Nucleotides / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D015870:Gene Expression / Q000187:drug effects; D006632:Histamine / Q000378:metabolism; D007034:Hypothalamus, Posterior / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D066298:In Vitro Techniques; D008297:Male; D008761:Methylhistamines / Q000494:pharmacology; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000145:classification / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013696:Temperature; D015244:Thiorphan / Q000031:analogs & derivatives / Q000494:pharmacology
D000227:Adenine Nucleotides; D007093:Imidazoles; C489787:MAP2 protein, rat; D008761:Methylhistamines; D008869:Microtubule-Associated Proteins; C111914:N(6)-methyl-2'-deoxyadenosine 3',5'-diphosphate; D058919:Purinergic P2 Receptor Antagonists; D012333:RNA, Messenger; D018094:Receptors, Metabotropic Glutamate; D018048:Receptors, Purinergic P2; C085130:S-acetylthiorphan; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; C115705:ciproxifan; D011732:Pyridoxal Phosphate; D000244:Adenosine Diphosphate; D006632:Histamine; D015244:Thiorphan