Cardiovascular Effects of the Essential Oil of Mentha x villosa and its Main Constituent, Piperitenone Oxide, in Normotensive Anaesthetised Rats: Role of the Autonomic Nervous System

Abstract

Cardiovascular effects of intravenous (i. v.) treatment with the essential oil of Mentha x villosa (EOMV) were investigated in pentobarbitone-anaesthetised rats. Additionally this study examines whether the major constituent of EOMV, piperitenone oxide (PO), is the active principle mediating EOMV-induced changes in mean aortic pressure (MAP) and heart rate (HR) and whether the autonomic nervous system is involved in the mediation of these cardiovascular effects. Two samples of EOMV have been tested: one contained 62.32 % of PO (sample 1) and the other contained a higher percent (95.87 %) of PO (sample 2). Intravenous injections of bolus doses (1 to 20 mg/kg) of both samples of EOMV elicited immediate and dose-dependent decreases in MAP and HR. These cardiovascular responses were also observed following i. v. injections of PO (1 to 20 mg/kg). However, maximal percent decreases in MAP and HR elicited by sample 2 of EOMV were significantly greater than those evoked by sample 1 of EOMV, while they were of the same order of magnitude as those elicited by PO. Pretreatment of rats with either bilateral vagotomy or i. v. methylatropine (1 mg/kg) did not modify significantly the hypotensive and bradycardic responses to EOMV. In contrast, pretreatment with i. v. hexamethonium (30 mg/kg) partially, but significantly, reduced the bradycardic effects of EOMV without affecting hypotension. The present study shows for the first time that i. v. treatment with EOMV in pentobarbitone-anaesthetised rats induces hypotensive and bradycardic effects, which appear mostly attributed to the actions of the major constituent of EOMV, PO. These cardiovascular effects appear to be independent since EOMV-induced bradycardia appears dependent upon the presence of an intact and functional sympathetic nerve drive to the heart, while EOMV-induced hypotension appears independent of the presence of an operational sympathetic nervous system. This suggests that hypotensive activity of EOMV may result from its vasodilatory effects directly upon vascular smooth muscle.

Key words

Mentha x villosa - Labiatae - essential oil - piperitenone oxide - cardiovascular effects - autonomic nervous system - rat

References

• 1 Matos F JA. Farmácias vivas. In: Edições UFC, Fortaleza, CE Brazil; 1994: pp. 127
• 2 Borba M OP, Silva J F, Montenegro L, Jugmann O, Cavalcanti M M, Albuquerque P MS. Frações ativas da Mentha crispa sobre camundongos albinos Swiss infectados com Schistosoma mansoni cepa São Lourenço da Mata. In : XI Simpósio de Plantas Medicinais do Brasil.  João Pessoa, PB Brazil; 1990: pp. 49
• 3 Melo A M, Pinho S, Santana C F, Santos E R, Souza I A. Primeiras observações sobre o uso da Mentha crispa em tricomoníase urogenital. In : XI Simpósio de Plantas Medicinais do Brasil. Curitiba, PR Brazil; 1992: pp. 160
• 4 Santana C F, Almeida E R, dos Santos E R, Souza I A. Actions of Mentha crispa hydroethanolic extract in patients bearing intestinal protozoan.  Fitoterapia,. 1992;  63 409-10
• 5 Hiruma C A. Estudo químico e farmacológico do óleo essencial das folhas de Mentha x villosa Hudson. Master Thesis, Departamento de Fisiologia e Farmacologia, Universidade Federal de Paraíba 1993 João Pessoa, PB, Brazil;
• 6 Matos F JA, Machado M IL, Craveiro A A, Alencar J W, Barbosa J M, da Cunhã E VL, Hiruma C A. Essential oil Mentha x villosa Huds. from northeastern Brazil.  Journal of Essential Oil Research. 1999;  11 41-4
• 7 Sousa P JC, Magalhães P JC, Lima C C, Oliveira V S, Leal-Cardoso J H. Effects of piperitenone oxide on the intestinal smooth muscle of the guinea pig.  Brazilian Journal of Medical and Biological Research. 1997;  30 787-91
• 8 Sousa P JC. Estudo Farmacológico de óleo essencial de Mentha x villosa e seu principal constituinte, óxido de piperitenona, em músculos lisos gastrointestinais de cobaia e pressão arterial de rato. Doctoral Thesis, Departamento de Fisiologia e farmacologia, Universidade Federal do Ceará 1999 Fortaleza, CE, Brazil;
• 9 Craveiro A A, Matos F JA, Alencar J W. Simple and inexpensive steam-generator for essential oils extraction.  Journal of Chemical Education. 1976;  53 562
• 10 Degouville A CL, Cavero I. Cross tachyphylaxis to endothelin isopeptide-induced hypotension. A phenomenon not seen with proendothelin.  British Journal of Pharmacology. 1991;  104 77-84
• 11 Lahlou S, Leal-Cardoso J H, Magalhães P JC. Essential oil of Croton nepetaefolius decreases blood pressure through an action upon vascular smooth muscle : studies in DOCA-salt hypertensive rats.  Planta Medica. 2000;  66 138-43
• 12 Sapru H N, Gonzalez E R, Krieger A J. Greater splanchnic nerve activity in the rat.  Brain Research Bulletin. 1982;  8 267-72
• 13 Vasquez E C, Krieger E M. Decreased chronotropic responses to adrenergic stimulation following sinoaortic denervation in rat.  Brazilian Journal of Medical and Biological Research. 1997;  15 377-87
• 14 Lahlou S, Pinto Duarte G, Demenge P. Central dopaminergic origin of bromocriptine induced tachycardia in normotensive rats.  Cardiovascular Research. 1993;  27 2022-7
• 15 Lahlou S. Involvement of spinal dopamine receptors in mediation of the hypotensive and bradycardic effects of systemic quinpirole in anaesthetised rats.  European Journal of Pharmacology. 1998;  353 227-37
• 16 Brezenof H E. Cardiovascular responses to noradrenaline in rat before and after administration of various anesthetics.  British Journal of Pharmacology. 1973;  49 565-72
• 17 Lahlou S, Leal-Cardoso J H, Magalhães P JC, Coelho-de-Souza A N, Pinto Duarte G. Cardiovascular effects of the essential oil of Croton nepetaefolius in rats: role of the autonomic nervous system.  Planta Medica. 1999;  65 553-7
• 18 Leal-Cardoso J H, Fonteles M C. Pharmacological effects of essential oils of plants of the northeast of Brazil.  Anais da Academia Brasileira de Ciências.. 1999;  71 201-13
• 19 Fogaça R TH, Cavalcante A DA, Serpa A KL, Souza, PJC, Coelho-de-Souza A N, Leal-Cardoso J H. The effects of essential oil of Mentha x villosa on skeletal muscle of the toad.  Phytotherapy Research. 1997;  11 552-7
• 20 Fruchgott R F, Zawadzki J V. The obligatory role of endothelial cells in the relaxation of arterial smooth-muscle by acetylcholine.  Nature. 1980;  288 373-6