Resveratrol inhibits nicotinic stimulation-evoked catecholamine release from the adrenal medulla

Abstract

Resveratrol has been known to possess various potent cardiovascular effects in animal, but there is little information on its functional effect on the secretion of catecholamines (CA) from the perfused model of the adrenal medulla. Therefore, the aim of the present study was to determine the effect of resveratrol on the CA secretion from the isolated perfused model of the normotensive rat adrenal gland, and to elucidate its mechanism of action. Resveratrol (10~100microM) during perfusion into an adrenal vein for 90 min inhibited the CA secretory responses evoked by ACh (5.32 mM), high K(+) (a direct membrane-depolarizer, 56 mM), DMPP (a selective neuronal nicotinic N(n) receptor agonist, 100microM) and McN-A-343 (a selective muscarinic M(1) receptor agonist, 100microM) in both a time- and dose-dependent fashion. Also, in the presence of resveratrol (30microM), the secretory responses of CA evoked by veratridine 8644 (an activator of voltage-dependent Na(+) channels, 100microM), Bay-K-8644 (a L-type dihydropyridine Ca(2+) channel activator, 10microM), and cyclopiazonic acid (a cytoplasmic Ca(2+)-ATPase inhibitor, 10microM) were significantly reduced. In the simultaneous presence of resveratrol (30microM) and L-NAME (an inhibitor of NO synthase, 30microM), the CA secretory evoked by ACh, high K(+) , DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid were recovered to a considerable extent of the corresponding control secretion compared with the inhibitory effect of resveratrol alone. Interestingly, the amount of nitric oxide (NO) released from the adrenal medulla was greatly increased in comparison to its basal release. Taken together, these experimental results demonstrate that resveratrol can inhibit the CA secretory responses evoked by stimulation of cholinergic nicotinic receptors, as well as by direct membrane-depolarization in the isolated perfused model of the rat adrenal gland. It seems that this inhibitory effect of resveratrol is exerted by inhibiting an influx of both ions through Na(+) and Ca(2+) channels into the adrenomedullary cells as well as by blocking the release of Ca(2+) from the cytoplasmic calcium store, which are mediated at least partly by the increased NO production due to the activation of NO synthase.

Keywords: Adrenal medulla; Catecholamine secretion; Cholinergic receptors; Nitric oxide; Resveratrol.

Fig. 1

Dose-dependent effect of resveratrol on the secretory responses of catecholamines (CA) evoked by acetylcholine (upper) and high potassium (lower) from the isolated perfused rat adrenal glands. The CA secretion by a single injection of ACh (5.32×10^-3 M) and K⁺ (5.6×10^-2 M) in a volume of 0.05 ml was evoked at 15 min intervals during loading with 10, 30 and 100µM of resveratrol for 90 min as indicated by the arrow marks, respectively. The numbers in parentheses indicate the number of rat adrenal glands. Vertical bars on the columns represent the standard error of the mean (SEM). Ordinate: the amounts of CA secreted from the adrenal gland (% of control). Abscissa: collection time of perfusate (min). Statistical difference was obtained by comparing the corresponding control (CONTROL) with each concentration- treated group of resveratrol. ACh- and high K⁺-induced perfusates were collected for 4 minutes, respectively. ^**p<0.01. ns: not statistically significant.

Fig. 2

Dose-dependent effect of resveratrol on the CA secretory responses evoked by DMPP (upper) and McN-A- 343 (lower) from the isolated perfused rat adrenal glands. The CA secretion by perfusion of DPPP (10^-4 M) and McN-A-343 (10^-4 M) for 2 min was induced at 20 and 15 min intervals during loading with 10, 30 and 100µM of resveratrol for 90 min, respectively. Statistical difference was obtained by comparing the corresponding control (CONTROL) with each concentration- pretreated group of resveratrol. DMPP- and McN-A-343-induced perfusates were collected for 8 and 4 minutes, respectively. Other legends are the same as in Fig. 1. ^*p<0.05, ^**p<0.01. ns: not statistically significant.

Fig. 3

The time-dependent effects of resveratrol on the CA release evoked by Bay-K-8644 (upper) and cyclopiazonic acid (lower) from the rat adrenal glands. Bay-K-8644 (10^-5 M) and cyclopiazonic acid (10^-5 M) were perfused into an adrenal vein for 4 min at 15 min intervals during loading with resveratrol (30µM) for 90 min. Other legends are the same as in Fig. 1. ^*p<0.05, ^**p<0.01. ns: not statistically significant.

Fig. 4

Time-course effects of resveratrol on the CA release evoked by veratridine from the rat adrenal glands. Veratridine (10^-4 M) was perfused into an adrenal vein for 4 min at 15 min intervals during loading with resveratrol (30µM) for 90 min. Other legends are the same as in Fig. 1. ^**p<0.01.

Fig. 5

Effect of resveratrol plus L-NAME on the CA secretory responses evoked by acetylcholine (upper) and high potassium (lower) from the perfused rat adrenal glands. The CA secretion by a single injection of ACh (5.32×10^-3 M) and K⁺ (5.6×10^-2 M) in a volume of 0.05 ml was evoked at 15 min intervals during simultaneous loading with resveratrol (30µM) plus L-NAME (30µM) for 90 min. Statistical difference was obtained by comparing the corresponding control (CONTROL) with resveratrol-treated group or group treated with resveratrol+L-NAME. Other legends are the same as in Fig. 1. ^*p<0.05, ^**p<0.01. ns: not statistically significant.

Fig. 6

Effect of resveratrol plus L-NAME on the CA secretory responses evoked by DMPP (upper) and McN-A-343 (lower) from the perfused rat adrenal glands. The CA secretion by perfusion of DPPP (10^-4 M) and McN-A-343 (10^-4 M) for 2 min was induced at 20 and 15 min intervals after preloading with resveratrol (30µM) plus L-NAME (30µM) for 90 min, respectively. Other legends are the same as in Fig. 1 and 5. ^**p<0.01. ns: not statistically significant.

Fig. 7

Effects of resveratrol plus L-NAME on the CA secretory responses evoked by Bay-K-8644 (upper) and cyclopiazonic acid (lower) from the rat adrenal glands. Bay-K-8644 (10^-5 M) and cyclopiazonic acid (10^-5 M) were perfused into an adrenal vein for 4 min at 15 min intervals during simultaneous loading with resveratrol (30µM) for 90 min. Other legends are the same as in Fig. 1 and 5. ^*p<0.05, ^**p<0.01. ns: not statistically significant.

Fig. 8

Comparison of nitric oxide (NO) production before (CONTROL) and after administration of resveratrol in the isolated perfused rat adrenal medulla. Perfusate sample was taken for 8 min after loading the perfusion of resveratrol (100µM) at a rate of 0.31 ml/min. Ordinate: the amounts of NO released from the adrenal medulla (% of control). Abscissa: treatment (before and after resveratrol). Statistical difference was made by comparing the control with resveratrol-treated group. ^**p<0.01.