Application of the UV-vis spectrophotometry method for the determination of glutamate in the cerebrospinal fluid of rats.

In experimental nociception models, there is an increase in the glutamate cerebrospinal fluid (CSF) and a decrease in its levels in analgesic treatments. For the determination of glutamate in CSF, an analytical UV spectrophotometric method was developed and validated. The measurements on the UV-vis spectrophotometer were performed after the derivatization reaction of the neurotransmitter, when reading in the ultraviolet (UV) region, at the maximum absorption wavelength of 265 nm. The technique presented excellent linearity, as well as good intraday and interday precision, with coefficients of variation less than 15 %, and a correlation coefficient close to 1.0 (lower dispersion of the experimental set points and lower uncertainty of the estimated regression coefficients). The analytical conditions that were established by the ultraviolet spectrophotometric method demonstrated selectivity, linearity, precision, specificity, robustness, and accuracy. This is suitable for the quantitative determination of glutamate in the CSF. The technique developed by UV-vis spectrophotometry for glutamate dosing was fast, efficient, easy to perform, and more economically accessible when compared to current standard techniques. When comparing the data obtained in this study with the results of the official methodology, in which HPLC and spectrofluorimetry were used, it was observed that the closest values of glutamate release occurred between the spectrofluorimeter and the UV-vis spectrophotometer. The UV-vis spectrophotometry method for the determination of CSF glutamate has been shown to be accurate, reproducible, and satisfactory, making it an extremely advantageous and a viable alternative for the determination of amino acid glutamate.

The effects of Phα1ß, a spider toxin, calcium channel blocker, in a mouse fibromyalgia model.

This study investigated the effects of Phα1ß, pregabalin and diclofenac using an animal model of fibromyalgia (FM). Repeated administration of reserpine (0.25 mg/kg sc) once daily for three consecutive days significantly decreased thermal hyperalgesia, mechanical allodynia, and dopamine and serotonin content in the brain on the 4th day. Phα1ß and pregabalin treatment completely reverted the mechanical allodynia and thermal hyperalgesia induced by reserpine treatment on the 4th day, but diclofenac was ineffective. Reserpine treatment significantly increased the immobility time in the forced swim test, which is indicative of depression in the animals. Phα1ß, but not pregabalin, reduced the immobility time (56%), suggesting that Phα1ß may control persistent pathological pain in FM.