Effects of stanniocalcin 1 hormone on lactate metabolism in rat kidney under fed and fasted conditions.

To test the hypothesis of STC-1 participation in maintenance of glucose homeostasis in fed and fasting (48 h) rats, we investigated that this hormone may be implicated in the regulation of renal gluconeogenesis pathway from lactate and lactate oxidation in renal cortex and medulla. Our results demonstrate the hSTC-1 role on lactate metabolism in the renal cortex and medulla from fed and fasting rats. hSTC-1 increased the gluconeogenesis activity in fed state in renal cortex, and this increase was induced by raise in Pck1 gene expression. In fasting animals hSTC-1 increase the renal medulla gluconeogenesis activity, but Pck1 gene expression was not alter. The stimulatory effect of hSTC-1 on C-lactate oxidation occurred only in the renal cortex from fed rats. These findings show the hSTC-1 contribution to lactate homeostasis and supplies glucose to other tissues. This response may represent a strategy of action of STC-1 in response to fasting stress as postulated by different authors. On the other hand, hSTC-1 acts downstream of adenylcyclase pathway, decreasing the gluconeogenesis activity induced by cAMP intracellular increase or stimulating the phosphodiesterase activity in the renal cortex. However, no hSTC-1 effect on C-lactate oxidation was found after increase in the intracellular cAMP. The findings also revealed that the renal cortex and medulla respond differently to hSTC-1, possibly due to the higher level of STC-1 gene expression in inner renal medulla than in renal cortex.