Adenosine triphosphate and diadenosine pentaphosphate induce [Ca(2+)](i) increase in rat basal ganglia aminergic terminals.
Synaptosomal preparations from rat midbrain exhibit specific responses to both ATP and Ap(5)A, which stimulate a [Ca(2+)](i) increase in the presynaptic terminals via specific ionotropic receptors, termed P2X, and diadenosine polyphosphate receptors. Aminergic terminals from rat brain basal ganglia were characterized by immunocolocalization of synaptophysin and the vesicular monoamine transporter VMAT2 and represent 29% of the total. These aminergic terminals respond to ATP and/or Ap(5)A with an increase in the intrasynaptosomal calcium concentration as measured by a microfluorimetric technique. This technique, which allows single synaptic terminals to be studied, showed that roughly 8.2% +/- 1.6% of the aminergic terminals respond to ATP, 16.9% +/- 1.3% respond to Ap(5)A, 32.6% +/- 0.8% to both, and 42.3% +/- 1.5% of them have no response. Immunological studies performed with antibodies against ionotropic ATP receptor subunits showed positive labelling with anti-P2X(3) antibodies in 39% of the terminals. However, colocalization studies of VMAT and P2X(3) receptor subunit indicate that only 25% of the aminergic terminals also contain this receptor subtype. These results demonstrate that the aminergic terminals from the rat brain basal ganglia are to a large extent under the modulation of presynaptic nucleotide and dinucleotide receptors.
Giraldez
L
L
Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain.
Díaz-Hernández
M
M
Gómez-Villafuertes
R
R
Pintor
J
J
Castro
E
E
Miras-Portugal
M T
MT
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001479:Basal Ganglia / Q000187:drug effects* / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects*; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D006168:Guinea Pigs; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis*; D026901:Membrane Transport Proteins; D051379:Mice; D008856:Microscopy, Fluorescence; D009419:Nerve Tissue Proteins / Q000032:analysis*; D009479:Neuropeptides; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000032:analysis*; D058477:Receptors, Purinergic P2X3; D013574:Synaptosomes / Q000187:drug effects* / Q000502:physiology; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins
D015226:Dinucleoside Phosphates; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; C546409:P2rx3 protein, mouse; C546410:P2rx3 protein, rat; D018048:Receptors, Purinergic P2; D058477:Receptors, Purinergic P2X3; C493453:Slc18a2 protein, mouse; C493454:Slc18a2 protein, rat; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; D000255:Adenosine Triphosphate