| Objective:1.To analyze the effect of different electric stimulation parameters on the blood flow of dura matter adjacent to superior sagittal sinus(SSS)in rats.2.To analyze the change of blood flow induced by electrical stimulation on dura matter adjacent to SSS and the effect of sumatriptan on it in rats.3.To establish a new model for vascular headache and observe the behavioural characteristics induced by electrical stimulation with different frenquencies on dura mater adjacent to SSS in conscious rats.4.To study the effect of morphine for different dosages on behaviours of rats evoked by electrical stimulation on dura mater adjacent to SSS.5.To analyze the changes of plasma concentration of CGRP and SP after electrical stimulation on dura mater adjacent to SSS by means of radioimmunity methods.Methods:1.According to orthogonal layout of L9(34),three electric stimulation parameters which were classified into three levels were evaluated: frequency(1Hz,5Hz,30Hz),duration(250μs,500μs,1000μs)and voltage(3V, 6V,9V).Dura matter adjacent to SSS in the rat was stimulated applying different combinations of stimulation parameters and blood flow of dural matter was measured using laser doppler perfusion imager(LDI)in different groups.2.Eighteen rats were randomly divided into control,electrical stimulation and sumatriptan group.The dura matter adjacent to SSS was stimulated electrically with square wave of 30Hz,6V and 250μs and the blood flow on dura matter was measured using LDI in different groups.3.Eighty-three rats were randomly divided into eight groups and a electrode was fixed to the dura mater of each rat.Three days after surgery,electrical stimulatoin of 1Hz,2Hz,5Hz,10Hz,20Hz,50Hz and 100Hz were performed and related behaviours were observed for 5 min respectively.Rats in the control group were operated but not stimulated.Nociceptive scores were calculated by a weight score method according to different types of behaviours at the end of the observation.4.Forty rats were randomly assigned to control group and three mophine groups. Rats were given intraperitoneal injection of mophine(1mg/kg,2mg/kg or 4mg/kg)and physiological saline respectively to compare the change of behaviours induced by electrical stimulation on dura mater adjacent to SSS.5.Thirteen rats were randomly divided into control group and stimulation group in which the dura matter adjacent to SSS was stimulated electrically with square wave of 20Hz,4mA and 250μs.The plasma concentrations of CGRP and SP in both groups were compared by means of radioimmunity methods.Results:1.The blood flow of dura matter was significantly(P=0.035)affected by the electrical stimulation frequency but was not significantly affected by other parameters such as duration(P=0.259)and voltage(P=0.293).2.The relative blood flow in control,electric stimulation and sumatriptan group was(2.61±4.43)%,(15.49±5.65)%and(-0.35±5.08)%respectively.There was significant difference of the relative blood flow among three groups(P＜0.01).However,there was no significant difference between the control group and the sumatriptan group.3.(1)There was no significant difference of the stimulation intensity in all groups except the control one(P=0.737).(2)Four types of behavioural characteristics including shaking head rhythmically,excessive grooming,"head-flick" and "torsion" were found after electrical stimulation in conscious rats.However,shaking head rhythmically is not regarded as pain-related behaviour.(3)The time of excessive grooming in 2 Hz,5Hz,10Hz,20Hz,50Hz and 100Hz groups was(0～37.5)s,115.5(61～135)s,130(45～177)s, 150(89.75～221.50)s,5(0～6.25)s and 0(0～20.5)s respectively and such behaviour was not found in control and 1Hz group.There was significant difference among all groups(P＜0.001).(4)"Head-flick" and "torsion" were not found in control,1Hz and 2Hz group. The number of these behaviours in 5Hz,10Hz,20Hz,50Hz and 100Hz groups was 0(0～1.25),7(1～12),10(7.25～14.75),4(2～6)and 2(1～5.5) respectively.There was significant difference among all groups(P＜0.001).(5)The nociceptive score in control,1Hz,2Hz,5Hz,10Hz,20Hz,50Hz and 100Hz groups was 0,0,0.25(0～0.5),2(0.875～2.5),4(2.5～4.5),5(3.5～6), 1.75(1.375～2.5)and 1.5(1～2.5)respectively.There was significant difference of the nociceptive score among the above groups(P＜0.0001).4.(1)The excessive grooming in control group and three morphine groups of 1mg,2mg and 4 mg lasted for 102(77.5～147.5)s,30.5(17.5～64.75)s, 23(2～60.25)s and 5(0～28.75)s respectively.There was significant difference among four groups(P=0.0011).(2)There was significant difference(P=0.012)of the number of "head-flick" and "torsion" among control group(13.9±9.8)and group of 1mg mophine(11.9±10.2),2mg morphine(3.8±3.4),4mg morphine(1.8±1.4).(3)The nociceptive score in control group and morphine group of 1mg,2mg, 4mg was 5.1±2.2,3.9±2.8,1.8±1.2 and 1.1±0.8 respectively.There was significant difference among four groups(P=0.014).5.There was significant difference of the concentration of plasma CGRP between control and stimulation group(50.60±7.16 vs.42.20±4.82,P=0.029). However,there was no significant difference of SP between two groups (308.59±43.07 vs.264.60±160.28,P=0.165).Conclusions:1.Frequency is the most important parameter when dura mater adjacent to SSS was electrically stimulated to establish a animal model for vascular headache.2.Electrical stimulation on dura mater adjacent to SSS can increase its blood flow which is able to be inhibited by sumatriptan.3.The nociceptive behaviour might be easilier induced at medium frequencies of electrical stimulation,expecially 20Hz,in conscious rats.4.Nociceptive behaviours including excessive grooming,"head-flick" and "torsion" can be inhibited by morphine with dose-effect relationship.5.The plasma concentrations of CGRP in rats decreased after electrical stimulation on dura mater but the concentrations of SP were unchanged. |
