Acute and chronic antihypertensive effects of Cinnamomum zeylanicum stem bark methanol extract in L-NAME-induced hypertensive rats.
BACKGROUND
Previous study showed that the aqueous extract of the stem bark of Cinnamomum zeylanicum possesses antihypertensive and vasodilatory properties. The present work investigates the acute and chronic antihypertensive effects of the methanol extract of Cinnamomum zeylanicum stem bark (MECZ) in L-NAME-induced hypertensive rats.


METHODS
The acute antihypertensive effects of MECZ (5, 10 and 20 mg/kg) administered intravenously were evaluated in rats in which acute arterial hypertension has been induced by intravenous administration of L-NAME (20 mg/kg). For chronic antihypertensive effects, animals were treated with L-NAME (40 mg/kg/day) plus the vehicle or L-NAME (40 mg/kg/day) in combination with captopril (20 mg/kg/day) or MECZ (300 mg/kg/day) and compared with control group receiving only distilled water. All drugs were administered per os and at the end of the experiment that lasted for four consecutive weeks, blood pressure was measured by invasive method and blood samples were collected for the determination of the lipid profile. The heart and aorta were collected, weighed and used for both histological analysis and determination of NO tissue content.


RESULTS
Acute intravenous administration of C. zeylanicum extract (5, 10 and 20 mg/kg) to L-NAME-induced hypertensive rats provoked a long-lasting decrease in blood pressure. Mean arterial blood pressure decreased by 12.5%, 26.6% and 30.6% at the doses of 5, 10 and 20 mg/kg, respectively. In chronic administration, MECZ and captopril significantly prevented the increase in blood pressure and organs' weights, as well as tissue histological damages and were able to reverse the depletion in NO tissue's concentration. The MECZ also significantly lower the plasma level of triglycerides (38.1%), total cholesterol (32.1%) and LDL-cholesterol (75.3%) while increasing that of HDL-cholesterol (58.4%) with a significant low atherogenic index (1.4 versus 5.3 for L-NAME group).


CONCLUSIONS
MECZ possesses antihypertensive and organ protective effects that may result from its ability to increase the production of the endogenous NO and/or to regulate dyslipidemia.
Department of Animal Biology and Physiology, University of Douala, Douala, Cameroon.
Paulin
P
Nyadjeu
Elvine Pami
EP
Nguelefack-Mbuyo
Albert Donatien
AD
Atsamo
Telesphore Benoît
TB
Nguelefack
Alain Bertrand
AB
Dongmo
Albert
A
Kamanyi
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D050197:Atherosclerosis / Q000517:prevention & control; D001794:Blood Pressure / Q000187:drug effects*; D002935:Cinnamomum zeylanicum; D006321:Heart / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008055:Lipids / Q000097:blood; D008297:Male; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D008517:Phytotherapy; D024301:Plant Bark; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D018547:Plant Stems; D051381:Rats; D017208:Rats, Wistar
D000959:Antihypertensive Agents; D008055:Lipids; D010936:Plant Extracts; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester