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

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 216 h after administration. The findings revealed that in innervated glands, vasopressin caused 59-74% decrease of norepinephrine (NE) 4 and 24 h after administration while in denervated glands it resulted in 18-65% release of NE 0.5 to 144 h after injection. This indicates that the splanchnic nerve prevents early phase (up to 0.5 h) 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 4 h 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 216 h after injection as compared to a slower increase (14%) in denervated glands 216 h after injection. Higher rate of resynthesis of E was encountered in the innervated glands 12 and 72 h after treatment. The findings clearly point out that the splanchnic nerve accelerates resynthesis of both NE and E induced by vasopressin.