Novel insights into how purines regulate pituitary cell function.
Purine nucleosides and nucleotides are widely distributed substances that exhibit a diverse range of effects in a number of tissues, acting as important extracellular signalling molecules in addition to their more established roles in cellular metabolism. They mediate their effects via activation of distinct cell surface receptors, termed adenosine (or P1) and P2 purinergic receptors. Although roles for adenosine and adenine nucleotides have been described previously in the pituitary gland, the distribution of the receptor subtypes and the effects of their activation on pituitary function are not well defined. Recent evidence, however, has emerged to describe a complex signalling system for purines in the pituitary gland. Data from a variety of studies have shown that the expression pattern, number and affinity of adenosine and/or P2 receptors may be cell-type specific and that non-endocrine in addition to endocrine cells elaborate these receptors. These variations, along with the diverse range of signalling pathways activated, dictate the response of individual cell types to extracellular purines, with roles now emerging for these substances in the regulation of hormone release, pituitary cell proliferation and cytokine/growth factor expression. In this review, we discuss these advances and examine some implications for pituitary growth control and the response of the hypothalamic-pituitary-adrenal axis to stress and inflammation.
Rees
D Aled
DA
Department of Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK. reesda@cf.ac.uk
Scanlon
Maurice F
MF
Ham
Jack
J
D002455:Cell Division / Q000502:physiology; D016228:Endothelial Growth Factors / Q000096:biosynthesis; D006801:Humans; D007249:Inflammation; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008222:Lymphokines / Q000096:biosynthesis; D010902:Pituitary Gland / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D010903:Pituitary Gland, Anterior / Q000378:metabolism; D010907:Pituitary Hormones / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000378:metabolism; D011687:Purines / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000032:analysis / Q000378:metabolism*; D018047:Receptors, Purinergic P1 / Q000032:analysis / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000032:analysis / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013312:Stress, Physiological / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; D008222:Lymphokines; D010907:Pituitary Hormones; D011687:Purines; D011983:Receptors, Purinergic; D018047:Receptors, Purinergic P1; D018048:Receptors, Purinergic P2; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors