Extracellular ATP Potentiates Steroidogenic Effect of Adrenocorticotropic Hormone in Bovine Adrenocortical Fasciculata Cells

Abstract

ABSTRACT-We examined the effect of extracellular adenosine 5'-triphosphate (ATP) on adrenocorticotropic hormone (ACTH)-and angiotensin II-induced steroidogenesis in bovine adrenocortical fasciculata cells. The low concentration of ATP (5 mM) potentiated ACTH-induced steroidogenesis synergistically. However, the purine derivative did not affect angiotensin II-induced steroidogenesis. Although adenosine (100 mM) (a metabolite of ATP) showed a weak steroidogenic effect, it did not potentiate ACTH-induced steroidogenesis. ATP also enhanced the steroidogenesis by NaF synergistically in bovine adrenocortical cells, but did not potentiate forskolin-and dibutyryl cyclic AMP-induced steroidogenesis. The stimulating effect of ACTH on cyclic AMP production was synergistically accelerated by ATP (5 mM), which has no effect by itself on cyclic AMP formation. These results suggest that extracellular ATP affected the ACTH receptor-adenylyl cyclase coupling processes, and potentiation of steroidogenesis by ACTH ensued in bovine adrenocortical fasciculata cells.Keywords: Adrenal cortex, Adrenocorticotropic hormone, Steroidogenesis, ATP, P2Y receptor Extracellular adenosine 5'-triphosphate (ATP) plays many biological roles in diverse cell functions via its cell membrane receptors (1 -4). Receptors for ATP are classified into two groups: a ligand-gated ion channel P2X receptor family and a G protein-coupled P2Y receptor family (5). We previously reported that extracellular ATP stimulated glucocorticoid production (steroidogenesis) in bovine adrenocortical fasciculata cells (BAFC) via P2Y receptors at micromolar concentrations (6).Recently, the importance of cross-talk between two biological active substances on the functions in several kinds of cells and organs has been mentioned. In the case of extracellular ATP, the nucleotide potentiates the insulin secretion stimulated by acetylcholine in isolated perfused rat pancreas (7), and the cytosolic Ca 2+ response to parathyroid hormone in rat osteoblastic cells (8). In steroidogenic organs, the cross-talk between serotonin and angiotensin II (9), interleukin-6 and adrenocorticotropic hormone (ACTH) (10) in rat adrenal steroidogenesis and angiotensin II and ACTH on cyclic AMP formation in bovine adrenal glomerulosa cells (11, 12) had been reported. From these observations, there might be possible cross-talk between extracellular ATP and ACTH (and/ or another steroidogenic substances) on glucocorticoid production in BAFC. Therefore, we investigated the effect of ATP on ACTH-and angiotensin II-induced steroidogenesis in BAFC. MATERIALS AND METHODS Primary culture of BAFCIsolated bovine adrenocortical fasciculata cells were prepared aseptically using collagenase and deoxyribonuclease I as previously described (13). The isolated cells were cultured in Ham's F-10 medium supplemented with 5% fetal calf serum, 10% newborn calf serum, 2.5% horse serum and antibiotics in a 24-well-type dish (10 -15 10 5 cells / well) in a CO2 incubator (humidified atmosphere of 5% CO 2 in air) at 37°C as repor...

NCI-H295R, a Human Adrenal Cortex-Derived Cell Line, Expresses Purinergic Receptors Linked to Ca2+-Mobilization/Influx and Cortisol Secretion

“…AngII is known to act on AT 1 receptors expressed in BAFC [10]. AT 1 is also known to be coupled to G q protein activation, resulting in Ca 2+ release from intracellular stores [23], [24].…”

“…This dominance of P2 over P1 for steroidogenesis is different from that seen in rats. Furthermore, BAFC are unique in that low concentrations of extracellular ATP, at levels that have no steroidogenic effect alone, enhance ACTH-induced glucocorticoid secretion synergistically [10]. Thus the P2 receptors expressed on adrenocortical cells may have something to do with defense systems under stressful conditions.…”

Adenosine 5′-(γ-thio) triphosphate (ATPγS) stimulates both P2Y receptors linked to inositol phosphates production and cAMP accumulation in bovine adrenocortical fasciculata cells

“…However, extracellular nucleotides also have potent steroidogenic effects in BAFC (Hoey et al, 1994;Kawamura et al, 1991;Nishi, 1999;Nishi et al, 2002). Besides their own effects, Kawamura et al reported that extracellular nucleotides enhance the steroidogenic effects of ACTH synergistically in BAFC (Kawamura et al, 2001). That is, nucleotides cause both their own steroidogenic effects and the modulation of ACTH effects.…”

Purinergic signaling pathways in endocrine system

“…ATP also potentiates the steroidogenic effect of ACTH in bovine fasciculate cells (Kawamura et al, 2001). In addition to ATP, ADP and uridine triphosphate stimulate calcium signaling and cortisol secretion (Hoey et al, 1994), ADP may also act through G s -coupled P2YRs (Nishi et al, 2002), and ATPγS stimulates both inositol phosphate production and cAMP accumulation (Nishi et al, 2004), suggesting a role of more than one P2R subtype in purinergic regulation of steroidogenesis in adrenocortical cells (Fig.…”