title: P2X purinoceptor subtypes on paraventricular nucleus neurones projecting to the rostral ventrolateral medulla in the rat.
abstract: The rostral ventrolateral medulla (RVLM) is essential for the generation of sympathetic nerve activity. The RVLM receives a substantial innervation from the hypothalamic paraventricular nucleus (PVN). Activation of P2X purinoceptors via ATP has been shown to mediate fast excitatory synaptic neurotransmission. There is mounting evidence to suggest the presence of P2X purinoceptors in hypothalamic nuclei, including the PVN. In this study, we determined whether P2X1-P2X6 purinoceptor subtypes were present on PVN neurones that projected to the RVLM. Injection of the retrogradely transported tracer, rhodamine-tagged microspheres, into the pressor region of the RVLM was used to identify the neurones in the PVN that innervated the RVLM. P2X1-P2X6 purinoceptors were detected by immunohistochemistry. Double-labelled neurones were quantified and expressed as a proportion of the retrogradely labelled neurones. The proportions of double-labelled neurones for each of the P2X purinoceptor subtypes varied, on average, from 14 to 29%. The P2X3 purinoceptor subtype was found to be the dominant purinoceptor subtype present on PVN neurones projecting to the RVLM. Additionally it was apparent that more than one P2X purinoceptor subtype was present on the PVN neurones projecting to the RVLM, since the sum of the average percentages of double-labelled neurones for each P2X purinoceptor subtype exceeded 100%. These findings highlight the presence of the P2X1-P2X6 purinoceptors on PVN neurones projecting to the RVLM. The results suggest a potential role for ATP in the PVN in the regulation of sympathetic nerve activity.
authors.affiliation: School of Medical Sciences, Division of Biosciences, RMIT University, PO Box 71, Bundoora 3083, Melbourne, Victoria, Australia.
authors.forename: Joo Lee
authors.initials: JL
authors.lastname: Cham
authors.forename: Neil C
authors.initials: NC
authors.lastname: Owens
authors.forename: Julian A
authors.initials: JA
authors.lastname: Barden
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lawrence
authors.forename: Emilio
authors.initials: E
authors.lastname: Badoer
mesh_terms: D000818:Animals; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry / Q000378:metabolism*; D009434:Neural Pathways / Q000737:chemistry / Q000378:metabolism; D009474:Neurons / Q000737:chemistry / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000032:analysis*; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; D058848:Receptors, Purinergic P2X4; D058485:Receptors, Purinergic P2X5; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: C546403:P2rx2 protein, rat; C546410:P2rx3 protein, rat; C548228:P2rx4 protein, rat; C546467:P2rx5 protein, rat; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; D058848:Receptors, Purinergic P2X4; D058485:Receptors, Purinergic P2X5; C110590:purinoceptor P2X6