ABSTRACT
Background: The neurite growth of dorsal root ganglion (DRG) explants is widely used for evaluating the promoting effects of neurotrophic factors on cultures. Counting the neurites directly is a tedious work because of the accuracy and the difficulty due to their branching and fasciculation. This study was aimed to compare quantitative measurement of neurite outgrowth, length and number of DRG explants in media containing estrogen (E2) and Schwann cell-conditioned medium (SCM). Methods: Schwann cells and DRG explants were harvested from nerve plexuses of P2-P3 rats and incubated separately. SCM was collected for treatment by adding into DRG culture. DRG explants were further incubated for 7 days with medium containing SCM, E2, SCM and E2. DRG cultures were stained for neurofilament to detect neurite growth. The neurite outgrowth, the length and number were measured by free software ImageTool. Results: The neurite outgrowth expressed as the percentage of pixels, occupied by the neurite extending from the ganglion, in the presence of E2 and SCM was the significantly increased parameter when compared to control. It was more reliable than the overestimated neurite outgrowth which resulted from the multiplying of neurite length and number. Conclusion: The neurite outgrowth was the parameter providing a robust means of evaluating the growth promoting activity of E2 and SCM. It could be rapidly measured. E2 might somehow increase the sensitivity of DRG neurons to the neurotrophic factors released from Schwann cells.
ABSTRACT
The purpose of this study was to investigate the short-term effects of mild chronic cerebral hypoperfusion on spatial learning and memory in rats with or without electrical stimulation treatment. Male Sprague Dawley rats weighing 300–360g were randomly assigned into seven groups (n=8) of right common carotid artery occlusion (RCO), left common carotid artery occlusion (LCO), non-surgery (NS) and sham operated (sham) groups. Chronic cerebral hypoperfusion was induced by permanent ligation of either right or left common carotid artery. Electrical stimulation (stim) was delivered to the NS-stim, RCo-stim and LCO-stim groups for a period of 30 min, once a day from day 1–5 after arterial occlusion. Evaluations of spatial learning and memory were assessed in a Morris water maze at five days after arterial occlusion. Results revealed that five days of mild cerebral hypoperfusion induced either by permanent right or left common carotid occlusion had no effect on spatial leaning and memory when compared with the sham group. But when we compared the RCO and the LCO rats, we found that the RCO rats performed significantly better than the LCO rats on the second day of leaning; however; their performance tended to become persistently slower in the later phase than that of the LCO rats. Furthermore, the LCO rats tended to have better spatial memory than the RCO rats. Electrical stimulation therapy significantly enhanced spatial learning in NS and LCO rats but had no effect on the RCO rats. These findings may suggest that unilateral carotid occlusion may induce only short-term mild deficit in spatial learning in rats, and electrical stimulation treatment may help in improving mild cognitive impairment caused by cerebral hypoperfusion.
ABSTRACT
The purpose of this study was to determine the relationships between the pattern of vertebral artery flow and the alignment of the cervical spine in a study group of 25 subjects with signs and symptoms related to vertebral artery insufficiency, compared with 25 age-and sex-matched healthy subjects (control group). The relative amplitude of pulsatile flow of extracranial vertebral arteries was measured by using a Grass photoelectric pulse sensor. The procedures comprised: (a) measurement of vertebral flow when the subjects were sitting with heads in the neutral, flex, extend and rotate positions; (b) an electromyogram (EMG) of the trapezius muscle in both neck and shoulder by disc electrodes; and (c) evaluation of the alignments from radiographs of the anterior, posterior, lateral and oblique view of the cervical spine. Results: Statistically, the extracranial vertebral flow (EVBF) in the study group was significantly lower than that in the control group. The frequency of vertebral asymmetry (more than 50%) was significantly higher in the study group (16 out of 25 subjects) than in the control group (seven out of 25 subjects). A statistically significant reduction of the vertebral flow was found in both groups when the head was flexed, extended and rotated (p < 0.05). However, a further reduction of the vertebral flow accompanying changes in head position in the study group, who initially had low blood flow, frequently resulted in dizziness, neck pain and blurred vision. The present results revealed that attenuation of the vertebral flow in the study subjects was associated with a significant increase in contraction of the trapezius muscle. The frequency of mild cervical spondylosis was similarly found in both groups (six out of 20 in the control group and 10 out of 20 in the study group). However, the vertebral flows of the 16 subjects with mild cervical spondylosis were significantly lower than in the subjects with normal cervical spine alignment.