Effect of butylidenephthalide on calcium mobilization in isolated rat aorta

Mechanisms of butylidenephthalide for twitch facilitation in electrically stimulated mouse vas deferens

CONTEXT

The rhizome of Ligusticum chuaxiong Hort. (Umbelliferae) has been used by Chinese for several thousand years. Its main constituent, butylidenephthalide (Bdph), was proved to be active in inhibiting rat uterine contractions induced by prostaglandin F_2α and was reported to be a nonspecific antispamodic and a blocker of voltage-dependent Ca²⁺ channels (VDCCs).

OBJECTIVES

The present study investigates the mechanisms of Bdph for twitch facilitation in ICR mouse vas deferens (MVD).

MATERIALS AND METHODS

Electrical field stimulation (EFS, supramaximal voltage ranging from 60-90 V, 1 ms, 0.2 Hz) was applied to the isolated MVD in Krebs solution. Interactions between Bdph (50 µM) and calcium antagonist (verapamil, diltiazem or aspaminol) on the EFS-evoked twitch responses were determined. The number of experiments was 3-18.

RESULTS

Bdph (50 µM)-induced twitch facilitations from 100 to 391.9% were unrelated to activation of postjunctional cholinergic or adrenergic receptors. Verapamil and Bdph unabolished the twitch facilitation each other. Diltiazem unabolished the Bdph-induced twitch facilitation. In contrast, Bdph abolished those induced by diltiazem. Aspaminol at 20 μM abolished the Bdph-induced twitch facilitation. In contrast, Bdph abolished those induced by aspaminol. Tetraethylammonium and 4-aminopyridine, the K⁺ channel blockers, significantly augmented the Bdph-induced twitch facilitation.

DISCUSSION AND CONCLUSIONS

Bdph may bind to the different, more and same subtypes of VDCCs from verapamil, than diltiazem, and as aspaminol does on prejunctional membrane, respectively. Besides a blocker of VDCCs, Bdph may be a blocker of K⁺ channels on prejunctional membrane. Thus, Bdph depolarized the membrane and facilitated the cumulative Ca²⁺-induced twitch responses.

Butylidenephthalide antagonizes cromakalim-induced systolic pressure reduction in conscious normotensive rats

Background

Butylidenephthalide (Bdph), a main constituent of Ligusticum chuanxiong Hort., was reported to have selective antianginal effect without changing blood pressure in conscious rat. Recently, we have observed that Bdph antagonized cromakalim, an ATP-dependent K⁺ channel opener, in guinea-pig trachea. Thus, we were interested in investigating whether Bdph at the dose without changing blood pressure antagonized cromakalim-induced systolic pressure reduction in conscious rats.

Methods

Systolic arterial pressures of conscious rats were determined by using the indirect tail-cuff method.

Results

Bdph (30 mg/kg, i.p.) did not affect baseline systolic pressure in conscious normotensive and spontaneous hypertensive rats. Bdph (30 mg/kg, i.p.) also did not affect log dose–response curves of prazosin, clonidine and Bay K 8644, a Ca²⁺ channel activator, in normotensive rats. However, Bdph (30 mg/kg, i.p.) similar to 4-aminopyridine (4-AP, 0.4 mg/kg, i.p.), a K⁺ channel blocker, non-parallelly but surmountably, and partially similar to glibenclamide (GBC, 10 mg/kg, i.v.), an ATP-sensitive K⁺ channel blocker, surmountably but not parallelly rightward shifted the log dose-systolic pressure reduction curve of cromakalim, an ATP-sensitive K⁺ channel opener, in normotensive rats, respectively.

Discussion

The antagonistic effect of Bdph against cromakalim was similar to that of 4-AP, a K+ channel blocker of Kv1 family, and partially similar to that of GBC, an ATP-sensitive K+ channel blocker. Thus, Bdph may be a kind of K+ channel blockers, which have been reviewed to have a potential clinical use for Alzheimer disease. Indeed, Bdph has also been reported to reverse the deficits of inhibitory avoidance performance and improve memory in rats. Recently, 4-AP was reported to treat Episodic ataxia type 2 (EA2) which is a form of hereditary neurological disorder. Consistently, Bdph was recently reported to have antihyperglycemic activity in mice, since GBC is a powerful oral hypoglycemic drug.

Conclusions

Bdph similar to 4-AP and partially similar to GBC may block K_v1 family and ATP-sensitive K⁺ channels in conscious normotensive rats.

Butylidenephthalide blocks potassium channels and enhances basal tension in isolated guinea-pig trachea

Butylidenephthalide (Bdph, 30~300 μM), a constituent of Ligusticum chuanxiong Hort., significantly enhanced tension in isolated guinea-pig trachea. In this study, we investigate the mechanism(s) of Bdph-induced contraction in the tissue. Isolated trachea was bathed in 5 mL of Krebs solution containing indomethacin (3 μM), and its tension changes were isometrically recorded. Cromakalim (3 μM), an ATP-dependent K⁺ channel opener, significantly antagonized the Bdph-induced enhancement of baseline tension. Bdph (300 μM) also significantly antagonized cromakalim-induced relaxation. Bdph (300 μM) did not significantly influence the antagonistic effects of glibenclamide (GBC, 1 μM) and tetraethylammonium (TEA, 8 mM) against the cromakalim-induced relaxation. However, Bdph (300 μM) and 4-aminopiridine (4-AP, 5 mM), a blocker of K_v1 family of K⁺ channels, in combination significantly rightward shifted the log concentration-relaxation curve of cromakalim. The antagonistic effect of the combination almost equals the sum of the individual effects of Bdph and 4-AP, suggesting that the antagonistic mechanism of Bdph may be similar to that of 4-AP. All calcium channel blockers influenced neither the baseline tension nor antagonistic effect of Bdph against cromakalim. In conclusion, Bdph may be similar to 4-AP, a blocker of K_v1 family of K⁺ channels, to enhance the baseline tension of guinea-pig trachea.

n-butylidenephthalide protects against dopaminergic neuron degeneration and α-synuclein accumulation in Caenorhabditis elegans models of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is the second most common degenerative disorder of the central nervous system that impairs motor skills and cognitive function. To date, the disease has no effective therapies. The identification of new drugs that provide benefit in arresting the decline seen in PD patients is the focus of much recent study. However, the lengthy time frame for the progression of neurodegeneration in PD increases both the time and cost of examining potential therapeutic compounds in mammalian models. An alternative is to first evaluate the efficacy of compounds in Caenorhabditis elegans models, which reduces examination time from months to days. n-Butylidenephthalide is the naturally-occurring component derived from the chloroform extract of Angelica sinensis. It has been shown to have anti-tumor and anti-inflammatory properties, but no reports have yet described the effects of n-butylidenephthalide on PD. The aim of this study was to assess the potential for n-butylidenephthalide to improve PD in C. elegans models.

METHODOLOGY/PRINCIPAL FINDINGS

In the current study, we employed a pharmacological strain that expresses green fluorescent protein specifically in dopaminergic neurons (BZ555) and a transgenic strain that expresses human α-synuclein in muscle cells (OW13) to investigate the antiparkinsonian activities of n-butylidenephthalide. Our results demonstrate that in PD animal models, n-butylidenephthalide significantly attenuates dopaminergic neuron degeneration induced by 6-hydroxydopamine; reduces α-synuclein accumulation; recovers lipid content, food-sensing behavior, and dopamine levels; and prolongs life-span of 6-hydroxydopamine treatment, thus revealing its potential as a possible antiparkinsonian drug. n-Butylidenephthalide may exert its effects by blocking egl-1 expression to inhibit apoptosis pathways and by raising rpn-6 expression to enhance the activity of proteasomes.

CONCLUSIONS/SIGNIFICANCE

n-Butylidenephthalide may be one of the effective neuroprotective agents for PD.

Synergistic interaction between the Ligusticum chuanxiong constituent butylidenephthalide and the nitric oxide donor sodium nitroprusside in relaxing rat isolated aorta

ETHNOPHARMACOLOGICAL RELEVANCE

Ligusticum chuanxiong Hort. (Umbelliferae), a traditional Chinese medicinal herb, is often prescribed together with nitric oxide donors for treating coronary heart diseases such as angina in China; however, studies concerning their pharmacological interaction are scarce.

AIM OF THE STUDY

The objective of the present study was to examine the interaction between the Ligusticum chuanxiong major active constituent butylidenephthalide (BDPH) and the nitric oxide donor sodium nitroprusside (SNP) in vasorelaxation.

MATERIALS AND METHODS

Vasorelaxation was examined in rat isolated aorta using an organ bath system.

RESULTS

BDPH and SNP interacted synergistically under 9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin H2 (U-46619)-induced tone. This synergism became greater with increasing U-46619 concentrations where Ca2+ sensitization contributed more significantly, and less when U-46619 was replaced with phenylephrine where participation of Ca2+ sensitization was minimal. BDPH-SNP synergism remained intact in the absence of external Ca2+, indicating that regulation of Ca2+ influx was not a requirement for the manifestation of this interaction.

CONCLUSIONS

The present study demonstrated the synergistic relaxation between BDPH and SNP in rat isolated aorta. This interaction is related to an enhancement of the effectiveness of SNP in producing relaxation under tone induced mainly by Ca2+ sensitization.

Mechanisms underlying the vasorelaxing effects of butylidenephthalide, an active constituent of Ligusticum chuanxiong, in rat isolated aorta

Butylidenephthalide (BDPH) is one of the most potent vasorelaxants isolated from Ligusticum chuanxiong Hort. The objective of the current study is to investigate the underlying vasorelaxation mechanisms in rat aorta. In 9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin F(2alpha) (U46619) precontracted preparations, endothelium removal, the nitric oxide (NO) synthase inhibitor Nomega-nitro-l-arginine methyl ester (l-NAME) and the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) partially inhibited the BDPH relaxation response to a similar extent. The cyclooxygenase inhibitor indomethacin, beta-adrenoceptor antagonist propranolol, adenylate cyclase inhibitors 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (SQ 22536) and 2',5'-dideoxyadenosine, and K(+) channel blocker tetraethylammonium had no effect. BDPH produced full relaxation against contractions induced by KCl and U46619 in the presence of the l-type voltage-operated Ca(2+) channel (Ca(v) 1.2) blocker nifedipine. In a receptor-operated Ca(2+) channel protocol where contraction was mediated by Ca(2+) re-addition in the presence of U46619 and nifedipine, BDPH produced relaxation. In the absence of extracellular Ca(2+), BDPH inhibited contractions induced by phorbol-12,13-dibutyrate and U46619. Our results suggest that BDPH-mediated vasorelaxation comprises both endothelium-dependent (NO) and independent components. It is suggested that BDPH acting through an inhibitory mechanism downstream to l-type voltage-operated and prostanoid TP receptor-operated Ca(2+) channels operating late in the contractile pathway.