Developmental changes in P2X purinoceptors on glycinergic presynaptic nerve terminals projecting to rat substantia gelatinosa neurones.
1. In mechanically dissociated rat spinal cord substantia gelatinosa (SG) neurones attached with native presynaptic nerve endings, glycinergic miniature inhibitory postsynaptic currents (mIPSCs) were recorded using nystatin perforated patch recording mode under voltage-clamp conditions. Under these conditions, it was tested whether the changes in P2X receptor subtype on the glycinergic presynaptic nerve terminals occur during postnatal development. 2. ATP facilitated glycinergic mIPSC frequency in a concentration-dependent manner through all developmental stages tested, whereas alphabeta-methylene-ATP (alphabeta-me-ATP) was only effective at later developmental stages. 3. alphabeta-me-ATP-elicited mIPSC frequency facilitation was completely occluded in the Ca2+-free external solution, but it was not affected by adding 10(-4) M Cd2+. 4. alphabeta-me-ATP still facilitated mIPSC frequency even in the presence of 10(-6) M thapsigargin, a Ca2+ pump blocker. 5. In later developmental stages, ATP-elicited presynaptic or postsynaptic responses were reversibly blocked by 10(-5) M pyridoxal-5-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), but only partially blocked by 10(-7) M 2',3'-O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP). However, alphabeta-me-ATP-elicited presynaptic or postsynaptic responses were completely and reversibly blocked by either 10(-5) M PPADS or 10(-7) M TNP-ATP. 6. alphabeta-me-ATP significantly reduced the evoked glycinergic IPSC amplitude in postnatal 28-30 day neurones, whereas it had no effect in 10-12 day neurones. 7. It was concluded that alphabeta-me-ATP-sensitive P2X receptors were functionally expressed on the glycinergic presynaptic nerve terminals projecting to SG neurones in later developmental stages. Such developmental changes of presynaptic P2X receptor subtypes might contribute to synaptic plasticity such as the regulation of neuronal excitability and the fine controlling of the pain signal in spinal dorsal horn neurones.
Jang
I S
IS
Cellular and System Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
Rhee
J S
JS
Kubota
H
H
Akaike
N
N
Akaike
N
N
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D005998:Glycine / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways; D009474:Neurons / Q000378:metabolism*; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058476:Receptors, Purinergic P2X2; D058848:Receptors, Purinergic P2X4; D013376:Substantia Gelatinosa / Q000166:cytology* / Q000254:growth & development / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D018756:GABA Antagonists; C546403:P2rx2 protein, rat; C548228:P2rx4 protein, rat; D010975:Platelet Aggregation Inhibitors; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; D058848:Receptors, Purinergic P2X4; C110590:purinoceptor P2X6; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; C045674:2',3'-O-(2,4,6-trinitro-cyclohexadienylidine)adenosine 5'-triphosphate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D005998:Glycine; D001640:Bicuculline