Growth hormone secretagogue receptor subtypes 1a and 1b are expressed in the human adrenal cortex

Ghrelin is an endogenous ligand of the growth hormone secretagogue receptors (GHS-Rs), two subtypes of which have been recognized: the biologically active 1a and the biologically inactive 1b subtype. Reverse transcription-polymerase chain reaction demonstrated ghrelin and GHS-R1b mRNAs in eight human adrenal cortexes, and GHS-R1a mRNA only in six of the eight adrenal specimens. The GHS-R1a expression was absent in the two adrenal cortexes obtained from 76- and 79-year old male patients. Since previous studies showed that ghrelin does not affect steroid-hormone secretion, the present findings suggest that ghrelin via the GHS-R1a could be involved in the autocrine-paracrine control of human-adrenal growth.