NEW PERSPECTIVES ON ENDOCRINE SIGNALLING Adenosine signalling pathways in the pituitary gland: one ligand, multiple receptors

Adenosine receptors are widely distributed in most species and mediate a diverse range of physiological and patho-logical effects. Although adenosine receptors have been identified in the pituitary gland, the distribution of the individual subtypes (A1, A2A, A2B, A3) has not been well defined. Furthermore, the effects of adenosine on pituitary trophic activity and function are not well established despite good evidence for growth- and immune-modulating properties of the nucleoside elsewhere. Recent advances have provided a more detailed descrip-tion of adenosine receptor distribution and function in the anterior pituitary and this commentary reviews these observations and highlights some of the possible implica-tions in relation to the control of the hypothalamic– pituitary–adrenal axis and the regulation of inflammation and pituitary cell growth