Purinergic receptors are part of a signalling system for proliferation and differentiation in distinct cell lineages in human anagen hair follicles

We investigated the expression of P2X5, P2X7, P2Y1 and P2Y2 receptor subtypes in adult human anagen hair follicles and in relation to markers of proliferation [proliferating cell nuclear antigen (PCNA) and Ki-67], keratinocyte differentiation (involucrin) and apoptosis (anticaspase-3). Using immunohistochemistry, we showed that P2X5, P2Y1 and P2Y2 receptors were expressed in spatially distinct zones of the anagen hair follicle: P2Y1 receptors in the outer root sheath and bulb, P2X5 receptors in the inner and outer root sheaths and medulla and P2Y2 receptors in living cells at the edge of the cortex/medulla. P2X7 receptors were not expressed. Colocalisation experiments suggested different functional roles for these receptors: P2Y1 receptors were associated with bulb and outer root sheath keratinocyte proliferation, P2X5 receptors were associated with differentiation of cells of the medulla and inner root sheaths and P2Y2 receptors were associated with early differentiated cells in the cortex/medulla that contribute to the formation of the hair shaft. The therapeutic potential of purinergic agonists and antagonists for controlling hair growth is discussed

Expression of P2X2 and P2X3 receptors in the rat carotid sinus, aortic arch, vena cava, and heart, as well as petrosal and nodose ganglia

With single- and double-labeling immunofluorescence techniques, the distribution patterns and morphological characteristics of P2X2- and P2X3-immunoreactive nerve fiber terminals and neuronal bodies have been studied in the main circulatory system baroreceptors and the nodose and petrosal ganglia of rats. A high density of P2X2- and P2X3-immunoreactive nerve fiber terminals was detected in the carotid sinus. P2X2- and P2X3-immunoreactive nerve fiber terminals were also distributed widely in the aortic arch, atrium, vena cava, and ventricles. Almost all the P2X2-immunoreactive nerve fiber terminals were immunoreactive for P2X3 receptors. P2X2- and P2X3-immunoreactive neuronal bodies were also detected in the nodose and petrosal ganglia, which are the sources of the P2X2- and P2X3-immunoreactive nerve terminals. P2X2 and P2X3 receptors were expressed in the same ganglionic neurons. These data indicate that extracellular ATP, via the homomeric P2X2 and P2X3 receptors, and heteromeric P2X2/3 receptor in the sensory receptors of carotid sinus, aortic arch, atrium, and vena cava, may be involved in the regulation of systematic circulation blood pressure