Neural modulation of lysine vasopressin-induced changes of catecholamines in the adrenal medulla of the pigeon

Abstract

Lysine vasopressin was injected (0.25 IU/100 g body wt) intraperitoneally only once to unilaterally splanchnic denervated pigeons. Adrenomedullary catecholamine (CA) content was measured spectrofluorometrically 0.5, 4, 12, 24, 72, 144 and 216h after administration. The findings revealed that in innervated glands, vasopressin caused 59-74% decrease of norepinephrine (NE) 4 and 24h after administration while in denervated glands it resulted in 18-65% release of NE 0.5 to 144h after injection. This indicates that the splanchnic nerve prevents early phase (up to 0.5h) of vasopressin-induced release of NE. Vasopressin also caused decrease of Epinephrine (E) from both the innervated (68-73%) and denervated (69-74%) glands 0.5 and 4h after injection indicating that the splanchnic nerve has no effect on vasopressin-induced release of E. Accelerated resynthesis of NE exceeding the control value (44-94%) was encountered 144 and 216h after injection as compared to a slower increase (14%) in denervated glands 216h after injection. Higher rate of resynthesis of E was encountered in the innervated glands 12 and 72h after treatment. The findings clearly point out that the splanchnic nerve accelerates resynthesis of both NE and E induced by vasopressin.