Korean J Physiol Pharmacol.  2016 Nov;20(6):629-639. 10.4196/kjpp.2016.20.6.629.

Gintonin facilitates catecholamine secretion from the perfused adrenal medulla

• Na SY
• Kim KH
• Choi MS
• Ha KS
• Lim DY

• KMID: 2364267
• DOI: http://doi.org/10.4196/kjpp.2016.20.6.629

Abstract

The present study was designed to investigate the characteristics of gintonin, one of components isolated from Korean Ginseng on secretion of catecholamines (CA) from the isolated perfused model of rat adrenal gland and to clarify its mechanism of action. Gintonin (1 to 30 µg/ml), perfused into an adrenal vein, markedly increased the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. The gintonin-evoked CA secretion was greatly inhibited in the presence of chlorisondamine (1 µM, an autonomic ganglionic bloker), pirenzepine (2 µM, a muscarinic M₁ receptor antagonist), Ki14625 (10 µM, an LPA₁/₃ receptor antagonist), amiloride (1 mM, an inhibitor of Na⁺/Ca²âº exchanger), a nicardipine (1 µM, a voltage-dependent Ca²âº channel blocker), TMB-8 (1 µM, an intracellular Ca²âº antagonist), and perfusion of Ca²âº-free Krebs solution with 5mM EGTA (a Ca²âºchelater), while was not affected by sodium nitroprusside (100 µM, a nitrosovasodialtor). Interestingly, LPA (0.3~3 µM, an LPA receptor agonist) also dose-dependently enhanced the CA secretion from the adrenal medulla, but this facilitatory effect of LPA was greatly inhibited in the presence of Ki 14625 (10 µM). Moreover, acetylcholine (AC)-evoked CA secretion was greatly potentiated during the perfusion of gintonin (3 µg/ml). Taken together, these results demonstrate the first evidence that gintonin increases the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. This facilitatory effect of gintonin seems to be associated with activation of LPA- and cholinergic-receptors, which are relevant to the cytoplasmic Ca²âº increase by stimulation of the Ca²âº influx as well as by the inhibition of Ca²âº uptake into the cytoplasmic Ca²âº stores, without the increased nitric oxide (NO). Based on these results, it is thought that gintonin, one of ginseng components, can elevate the CA secretion from adrenal medulla by regulating the Ca²âº mobilization for exocytosis, suggesting facilitation of cardiovascular system. Also, these findings show that gintonin might be at least one of ginseng-induced hypertensive components.

Keyword

Adrenal medulla; Catecholamine secretion; Gintonin; Hypertensive component; LPA receptor

MeSH Terms

Acetylcholine
Adrenal Glands
Adrenal Medulla*
Amiloride
Animals
Cardiovascular System
Catecholamines
Chlorisondamine
Cytoplasm
Egtazic Acid
Exocytosis
Ganglia, Autonomic
Nicardipine
Nitric Oxide
Nitroprusside
Panax
Perfusion
Pirenzepine
Rats
Veins
Acetylcholine
Amiloride
Catecholamines
Chlorisondamine
Egtazic Acid
Nicardipine
Nitric Oxide
Nitroprusside
Pirenzepine

Figure

• 

  Fig. 1 Concentration-dependent effect of gintonin on secretion of catecholamines (CA) (upper panel) and the perfusion effect of Ca2+-free Krebs plus EGTA on gintonin-evoked CA secretion from the perfused rat adrenal glands (lower panel).Gintonin (1~30 µg/ml) was infused into an adrenal vein for 4 min at 15 min intervals during 90 min. Perfusion of gintonin was made after perfusion with normal Krebs-bicarbonate solution for one hour before the experimental protocols were initiated. The data are expressed with mean±S.E. The statistical significance was compared between the periodic groups at each concentration. Abscissa: concentration of gintonin in M. The statistical difference was obtained by comparing gintonin-evoked CA secretory effect after treatment with Ca2+-free Krebs plus EGTA (5 mM) with its corresponding control. Ordinate: secretion of CA in ng or percentage for 4 min. The vertical columns and bars denote means and the standard errors, respectively. Number in the upper bracket indicates the number of animals used in the experiments. **p<0.01.

• 

  Fig. 2 The effects of nicardipine (upper) and TMB-8 (lower) on gintonin-evoked CA secretory responses in the perfused rat adrenal glands.Gintonin (10 µg/ml)-evoked CA secretion was induced at 15 min intervals during the perfusion with nicardipine (1 µM) or TMB-8 (10 µM) for 90 min. Statistical differences were compared between amounts of CA evoked by gintonin before and after treatment with nicardipine or TMB-8. Other legends are the same as in Fig. 1. **p<0.01.

• 

  Fig. 3 The effects of amiloride (upper) and nitroprusside (lower) on gintonin-evoked CA secretory responses in the perfused rat adrenal glands.Gintonin (10 µg/ml)-evoked CA secretion was induced at 15 min intervals during the perfusion with amiloride (1 mM) or nitroprusside (100 µM) for 90 min. Statistical differences were compared between amounts of CA evoked by gintonin before and after treatment with amiloride or nitroprusside. There was no significance between groups before and after treatment with nitroprusside. Other legends are the same as in Fig. 1. **p<0.01.

• 

  Fig. 4 The effects of chlorisondamine (upper) and pirenzepine (lower) on gintonin-evoked CA secretory responses in the perfused rat adrenal glands.Gintonin (10 µg/ml)-evoked CA secretion was induced at 15 min intervals during the perfusion with chlorisondamine (1 µM) and pirenzepine (2 µM) for 90 min. Statistical differences were compared between amounts of CA evoked by gintonin before and after treatment with chlorisondamine and pirenzepine. Other legends are the same as in Fig. 1. **p<0.01.

• 

  Fig. 5 The effects of Ki16425 on gintonin-evoked CA secretory responses (upper) and concentration-dependent effect of LPA-evoked CA secretion (lower) in the perfused rat adrenal glands.Gintonin (10 µg/ml)-evoked CA secretion was induced at 15 min intervals during the perfusion with Ki16425 (10 µM) for 90 min. LPA (0.3~3 µM) was infused into an adrenal vein for 4min at 15 min intervals during 90 min. Statistical differences were compared between amounts of CA evoked by gintonin before and after treatment with Ki16425. There was statistical significance between concentrations of LPA (p<0.01). Other legends are the same as in Fig. 1. **p<0.01.

• 

  Fig. 6 The effects of Ki16425 on LPA-evoked CA secretory responses (upper) and potentiative effect of gintonin on ACh-evoked CA secretion (lower) in the perfused rat adrenal glands.LPA (1 µM)-evoked CA secretion was induced at 15 min intervals during the perfusion with Ki16425 (10 µM). ACh (5.32 mM)-evoked CA secretion was induced at 15 min intervals during the perfusion with gintonin (10 µg/ml). Statistical differences were compared between amounts of CA evoked by LPA before and after treatment with Ki16425, and between amounts of CA evoked by ACh before and after treatment with gintonin. Other legends are the same as in Fig. 1. **p<0.01.

• 

  Fig. 7 Schematic diagram of possible action site of gintonin in the rat adrenal medulla.

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