Extract of Hypericum perforatum blocks caffeine‐induced locomotor activity in mice: a possible role of nitric oxide

Abstract

The present study investigated the effects of HPE on caffeine-induced locomotor activity in mice. Caffeine (4 -16 mg/kg) or saline were given to adult male Swiss-Webster mice, and the locomotor activity was immediately measured for 30 min. HPE (6-48 mg/kg) and saline were injected to another group of mice and the locomotor activity was measured 20 min later. HPE (6-24 mg/kg) was also administered to another group of mice 20 min before caffeine (16 mg/kg) injections and the locomotor activity was recorded for 30 min immediately after caffeine administrations. Finally L-arginine (1 g/kg) was administered i.p. 20 min before HPE (6 mg/kg) and the locomotor activity was measured as mentioned above. Each group of mice was used only once. Caffeine produced some significant increases in locomotor activity of the mice. HPE (6-24 mg/kg) significantly blocked the caffeine-induced locomotor hyperactivity. Pretreatment of L-arginine (1 g/kg) reversed the inhibitory effect of HPE (6 mg/kg) on caffeine-induced locomotor activity without producing any significant effect on locomotor activity of the mice when it was administered alone. The results suggest that HPE blocks caffeine-induced locomotor hyperactivity in mice. Furthermore, the inhibitory effect of HPE on caffeine-induced locomotor activity may be related to its NOS inhibitory property.

The Importance of l-Arginine:NO:cGMP Pathway in Tolerance to Flunitrazepam in Mice

“…The lack of effect of l -arginine and sildenafil on the tolerance to FNZ is difficult to explain. Some studies have shown that l -arginine up to 1000 mg/kg was effective without impairing open-field locomotor activity in mice (Ulusu et al 2005; Uzbay et al 2007). Therefore, it is possible that too low, inefficient doses of the NO precursor (up to 250 mg/kg) would account for the lack of effect of l -arginine on the tolerance to FNZ in the present experiments.…”

Renoprotective effect of Hypericum perforatum against diabetic nephropathy in rats: Insights in the underlying mechanisms

“…HP possesses potent antioxidant and anti‐inflammatory properties due to the presence of several bioactive compounds including naphthodianthrones (hypericin, pseudohypericin, protohypericin, protopseudohypericin, and cyclopseudohypericin), flavonoids (quercetin, rutin, and luteolin), hyperforin and tannins . It is used in folk medicine against diabetes mellitus (DM) . Many researchers have demonstrated the blood glucose lowering effect of HP; recent studies point out the potential therapeutic uses of HP regardless of hypoglycemic effect .…”

The mechanisms of action of St. John’s wort: an update

“…The hyperforin-induced cascade involving CREB and BDNF is controlled by Ca 2 + ions and occurs specifically in the cortex but not in the hippoistered alone. The inhibitory effect of SJW on caffeineinduced locomotor activity may therefore be related to an inhibition of the enzyme NO-synthetase [31].…”