The Effect of Hydroethanol Extract of Achillea Millefolium on β-adrenoceptors of Guinea Pig Tracheal Smooth Muscle

Different pharmacological effects of Achillea millefolium including its relaxant effect on smooth muscle have been shown previously. In the present study the stimulatory effect of the plant extract on β-adrenoceptor of tracheal muscle was examined in order to investigate one possible mechanism for its observed relaxant effect. Effect of three concentrations of hydroethanol extract, 10 nM propranolol, and saline on β-adrenoceptor was tested in two experimental groups including; nonincubated tracheal smooth muscles (group 1) and incubated tracheal smooth muscle with chlorpheniramine (group 2). Concentration response curves to isoprenaline were performed in precontracted tracheal smooth muscle in the presence of the extract, propranolol and saline. Values of EC₅₀ and CR-1 were measured. Leftward shifts in isoprenaline curves were observed in the presence of medium and high concentrations of the extract compared with saline in both groups. The values of EC₅₀ obtained in the presence of medium and high concentrations of the extract only in group 1 were nonsignificantly lower than that of saline. The values of CR-1 obtained in the presence of all concentrations of the extract in both groups were negative and significantly different with that of propranolol. The results indicated a small stimulatory effect of the extract on ß₂-adrenoceptors.     

The effect of hydro-ethanolic extract of Achillea millefolium on muscarinic receptors of guinea pig tracheal smooth muscle

Objective:

To investigate one possible mechanism for the observed relaxant effect of A. millefolium (Achillea millefolium), in the present study the inhibitory effect of the extract of this plant on muscarinic receptors was examined.

Materials and Methods:

The effects of three concentrations of aqueous-ethanolic extract, 10 nM atropine, and saline on muscarinic receptors were tested in three conditions: In non incubated tracheal smooth muscle (group 1), tracheal chain incubated with propranolol and chlorpheniramine (group 2), and the one incubated with propranolol (group 3).

Results:

The EC₅₀ obtained in the presence of all three concentrations of the extract were significantly higher compared to saline in groups 2 and 3 (P < 0.001and P < 0.01 in group 2 and 3 respectively). The EC₅₀ obtained in the presence of all concentrations of the extract in group 2 were significantly improved compared to groups 1 and 3 (P < 0.05 to P < 0.001). The maximum responses to methacholine in presence of only the higher concentration of the extract (0.8mg/ml) was significantly lower than that of saline in groups 1 (P < 0.05). There was neither significant difference between slopes of methacholine-response curves obtained in the presence of different concentrations of the extract and that of saline nor between the three groups. The values of (CR-1), obtained in the presence of all concentrations of the extract, were significantly lower compared to atropine in the first group but were not significantly different in other groups. The values of (CR-1) obtained in the presence of all concentrations of the extract were significantly improved in groups 2, compared to groups 1 and 3 (P < 0.05 to P < 0.001).

Conclusion:

These results showed an inhibitory effect for the extract of A. millefolium on muscarinic receptors of tracheal smooth muscle. A histamine (H₁) receptor blockade was also suggested for the extract.KEY WORDS: Achillea millefolium, guinea pig, hydroalcoholic extract, muscarinic receptors, trachea     

The effect of the extract of Crocus sativus on tracheal responsiveness and plasma levels of IL-4, IFN-γ, total NO and nitrite in ovalbumin sensitized Guinea-pigs

Ethnomedical relevance

Anti-inflammatory, anti oxidant and effect of Crocus sativus (C. sativus) on Th₁/Th₂ balance were described previously.

Aim of the study

The preventive effects of the extract of Crocus sativus on tracheal responsiveness and plasma levels of IL-4, IFN-γ, total NO and nitrite were examined on sensitized guinea pigs.

Materials and methods

Five groups of sensitized guinea pigs to ovalbumin (OVA), were given drinking water containing three concentrations of the extract of Crocus sativus, dexamethasone (S+D) or alone (group S). Tracheal responses (TR) of control animals (group C) and sensitized guinea pigs (n=6, for each group) to methacholine, OVA and the levels of IL-4, IFN-γ, total NO and nitrite in serum were examined.

Results

The TR to both methacholine and OVA, the levels of serum IL-4, total NO and nitrite in S guinea pigs were significantly increased but that of IFN-γ and IFN-γ/IL-4 ratio (Th₁/Th₂ balance) were decreased compared to the controls (p<0.05 to p<0.001). In the treated animals with dexamethasone and all concentrations of the extract, TR to both methacholine and OVA, IL-4, total NO and nitrite were significantly decreased but IFN-γ and IFN-γ/IL-4 ratio increased compared to S group (p<0.05 to p<0.001). The effects of the highest concentration of the extract was greater than those of other concentrations and the effect of dexamethasone (p<0.05 to p<0.01).

Conclusions

These results not only showed a preventive effect of C. sativus extract on tracheal responses and serum levels of inflammatory mediators in sensitized guinea pigs but also showed increased Th₁/Th₂ balance.