The Effect Of Eugenol On AVP Content In Plasma And CSF In Feverish Rats Induced By Yeast

IntroductionArginine vasopression ( AVP) is a nine - peptide posterior pituitary hormone secreted by hypothalami neuron, which distributes widely in the central nervous system. AVP is an endogenous antipyretical neurotransmitter and the sensitive target of its antipyretic function induced by V1 receptor is VSA. Infusion AVP into VSA of rats or rabbits can inhibit fever induced by endotoxin which causes apparent increasement in AVP content. In addition, AVP also participates in the antipyretical mechanisms of some drugs (such as sodium salicy-late, indomethacin and Qingkailing, etc).Being an effective ingredient in Chinese traditional medicine Chaihu, eugenol not only has intense antipyretic function, but also can decrease the normal body temperature of animals. It has been testified that eugenol could reverse the discharging activity of PO/AH temperature — sensitive neuron in normal rats to get a drop in normal body temperature. Also it could inhibit the increasement of PGE2 and cAMP in PO/AH of pyretic rabbits, thus cause a decreasement in body temperature. All the above information indicates eugenol's effect on the positive regulatory mediums of pyrexia, whereas no document demonstrated its effect on the negative ones, such as AVP. Therefore, this research observed the effect of celiac injected eugenol on the pyretic rats induced by microzyme through measuring AVP content in plasma and CSF and further investigated the antipyretical mechanisms of eugenol.Materials and Methods1. Reagent and instrumentYeast, eugenol, AVP radio - immunity assay kit, SN2202 digital thermometer.2. Animal grouping and temperature measuring40 healthy male Wistar rats (240 -260 g) were used in this study. Animals were caged individually and had free access to food and water. The rats were placed in an experimental environment three days before so as to adapt to the experimental condition. The animals were grouped into four groups randomly, i. e. control group, yeast group, eugenol group and antifebrile group. Rectal tempra-ture was monitored by insertion of a thermister probe 6cm in the rectum, the thermister was fed into the digital thermometer and was fixed at the root of the tail. Temperature records were taken three times at 15min intervals after the animals were stable and the mean was recorded as the basal body temperature. During the experiment, temperature records were taken at 30min intervals.3. Exponent collection and determination of AVP contentWhen the experiment was over, each rat was intraabdominally injected with urethan( lg/kg) to get anaesthesia. Then 0. lml CSF was imbibed through the occipital aperture and placed incentrifuge tube. Blood was extracted from the aortopulmonary, added with anticoagulant and then centrifuged to separate the serum. All the above reagents were stored in - 20*^ and AVP content was measured by the method of radio - immunity.Results1. Effects of eugenol to body temperature in pyretic rats induced by micro-zymeIn the yeast group, AT after injecting with yeast suspension is higher than the control group apparently! P <0.01). AT of the eugenol group is lower than the control apparently ( P < 0. 01). AT of the antifebrile group after injectingwith eugenol also decreased apparently incontrast to the yeast group (P <0.01).2. Effects of eugenol to microzyme induced fever on AVP level in CSF and plasma in ratsHypodermic injection with yeasts could cause an AVP increasement in plasma and CSF that was furthered by celiac injection with eugenol. The AVP content in plasma and CSF of the eugenol group was significantly high contrasted with the control group (P < 0.05).DiscussionYeast belongs to the fungi family whose pyrogen is the hole body and the capsule polysaccharide and protein inside the body. When acting on the body, yeast can activate EP cell to produce and release EP, which can act on thermo-genic center to release medium to change the set point. It has been proven that subcutaneous injection with yeast suspension can cause inflammatory fever in rats and cAMP increasement in hypothalami.AVP is a nine - peptide posterior pituitary hormone secreted by supraoptic nucleus and paraventricular nucleus in hypothalami, which distributes widely in the central nervous system. AVP is a neurotransmitter related to many ructions of the central nervous system. AVP has been recognized to have many functions including blood vessel contracting and antidiuresis. Also it is antifebrile. In many animals, infusion into the central nervous system with AVP can show its antifebrile effect. Meanwhile, AVP content also increased apparently after injecting pyrogen. The sensitive part of AVP antifebrile function is VSA. The increasement of negtive regulating medium such as AVP in the febrile animal can restraint the rising body temperature, which is protective to the body. The mechanisms of AVP antifebrile effect are explained as follows: 1) lowering the body temperature set point, changing the activity of body temperature effective ap-pararus, decreasing heat production and increasing heat loosing; 2) suppressing the production of EP by EP cells; 3) changing the activities of temperature -sensitive neurons, increasing discharging of the heat sensitive neurons and decreasing that of the cold sensitive ones.