The Depression Behavior And Change Of Serotonin Levels In Plasma And Tissues Of Different Brain Regions After Repetitive Electrical Stimulations Of Superior Sagittal Sinus In Rats

ObjectiveIn order to investigated the potential relationship between migraine and depression,the depression behaviors and spatial learning memory were observed followingrepetitive electrical stimulation on superior sagittal sinus of waking rats, and thechanges of serotonin levels in frontal lobe, hippocampus, hypothalamus and plasmawere detected.Methods1. Twenty-four male SD rats were randomly divided into experimental group (n=12)and control group (n=12). Each rat was separately reared in both groups.The rats in theexperimental group were given repetitive electrical stimulations (electric current1to2.5mA, frequency20Hz, sinusoidal wave, pulse width250μs, lasting time15minutesper time, once a day) for21days, after that electrodes were fixed on the superior sagittalsinus following exposed operation. The rats in control group were given no electricalstimulation after the same operation. The changes of nociceptive behaviour, such asexcessive grooming, head-flick and torsion, were respectively observed on the first dayand21st day.2. The depression behavior of rats were evaluated by liquid consumptionexperiment and open field experiment, and the abilities of spatial learning memory weretested by the Morris water maze testing after repetitive electrical stimulation for21days.3. The difference of serotonin levels in frontal lobe, hippocampus, hypothalamusand plasma of rats detected using enzyme linked immunosorbent assay method, was compared between the experimental group and control group.Results1. The number of excessive grooming, head-flick and torsion was increased on the21st day after repetitive electrical stimulation in the experimental group than that on thefirst day.2. After repetitive electrical stimulation for21days, the body weight increase of ratswas slower (p<0.01); sweet water consumption and sucrose preference decreasedsignificantly (p<0.01, p<0.01), pure water consumption increased significantly (p<0.01),grid crossed numbers in open field test and standing times decreased significantly(p<0.01, p<0.01) in the experimental group, compared with those in control group.3. After repetitive electrical stimulation for21days, escape latency time forsearching platform in the place navigation test increased significantly (p<0.01), targetquadrant pause time shortened significantly and safety platform crossed times decreasedsignificantly in spatial probe test (P<0.01, p<0.01), total distance and swim distance intarget quadrant decreased significantly (P<0.01, p<0.01) in the experimental group,compared with those in the control group.4. After repetitive electrical stimulation for21days, the5-hydroxytryptamine (5-HT)levels of brain tissues were significantly decreased in frontal lobe, hippocampus,hypothalamus and plasma of the experimental group (p<0.05, p<0.01, p<0.01, p<0.01)than those of the control group.Conclusions1. The nociceptive behaviour, including excessive grooming, head-flick and torsioncan be induced by repetitive electrical stimulation of superior saggital sinus of rats. Itmight be used to be the model of chronic vascular headache such as migraine.2. It was suggested that depression might be induced in the rat mode of chronicvascular headache such as migraine, because the depression behaviors were presentedafter repetitive electrical stimulation of superior sagittal sinus for21days.3. The spatial learning ability of rats decreased significantly after repetitiveelectrical stimulation of superior sagittal sinus for21days.4. The decrease of5-HT level in frontal lobe, hippocampus, hypothalamus andplasma may be involved in central mechanism of comorbidity of migraine anddepression.