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Fulltext Age-Dependent Anti-migraine Effects of Valproic Acid and Topiramate in Rats

Huang P, Kuo PH, Lee MT, Chiou LC, Fan PC

Front Pharmacol, 2018;9:1095.
PMID: 30319425 DOI: 10.3389/fphar.2018.01095

Background: Valproic acid (VPA) and topiramate (TPM), initially developed as antiepileptics, are approved for migraine prophylaxis in adults but not children. The differences in their antimigraine mechanism(s) by age remain unclear. Methods: A migraine model induced by intra-cisternal (i.c.) capsaicin instillation in pediatric (4-5 weeks) and adult (8-9 weeks) rats was pretreated with VPA (30, 100 mg/kg) or TPM (10, 30, 100 mg/kg). Noxious meningeal stimulation by the irritant capsaicin triggered trigeminovascular system (TGVS) activation mimicking migraine condition, which were assessed peripherally by the depletion of calcitonin gene-related peptide (CGRP) in sensory nerve fibers of the dura mater, the increased CGRP immunoreactivity at trigeminal ganglia (TG) and centrally by the number of c-Fos-immunoreactive (c-Fos-ir) neurons in the trigeminocervical complex (TCC). Peripherally, CGRP released from dural sensory nerve terminals of TG triggered pain signal transmission in the primary afferent of trigeminal nerve, which in turn caused central sensitization of the TGVS due to TCC activation and hence contributed to migraine. Results: In the VPA-treated group, the central responsiveness expressed by reducing the number of c-Fos-ir neurons, which had been increased by i.c. capsaicin, was significant in pediatric, but not adult, rats. Inversely, VPA was effective in peripheral inhibition of elevated CGRP immunoreactivity in the TG and CGRP depletion in the dura mater of adult, but not pediatric, rats. In TPM group, the central responsiveness was significant in both adult and pediatric groups. Peripherally, TPM significantly inhibited capsaicin-induced CGRP expression of TG in adult, but not pediatric, rats. Interestingly, the capsaicin-induced depletion of CGRP in dura was significantly rescued by TPM at high doses in adults, but at low dose in pediatric group. Conclusion: These results suggest VPA exerted peripheral inhibition in adult, but central suppression in pediatric migraine-rats. In contrast, TPM involves both central and peripheral inhibition of migraine with an optimal therapeutic window in both ages. These findings may clarify the age-dependent anti-migraine mechanism of VPA and TPM, which may guide the development of new pediatric anti-migraine drugs in the future.

Matched MeSH terms: Calcitonin Gene-Related Peptide
Procalcitonin as a predictor of severity and mortality in a cohort of patients hospitalised with COVID-19

Ahmed S, Ahmed ZA, Rashid NH, Mansoor M, Siddiqui I, Jafri L

Malays J Pathol, 2021 Dec;43(3):375-380.
PMID: 34958058

INTRODUCTION: To evaluate the association of Procalcitonin (PCT) with severity in Coronavirus disease 2019 (COVID-19), hospitalised patients and to test the hypothesis that it is an independent predictor of mortality.
MATERIALS AND METHODS: This study was conducted at Chemical Pathology, Department of Pathology and Laboratory Medicine and Department of Medicine, Aga Khan University (AKU), Karachi Pakistan. Electronic medical records of all in-patients including both genders and all age groups with documented COVID-19 from March to August 2020 were reviewed and recorded on a pre-structured performa. The subjects were divided into two categories severe and non-severe COVID-19; and survivors and non-survivors. Between-group differences were tested using the Chi-square and Mann-Whitney's U-test. The receiver operating characteristic curve was plotted for serum PCT with severity and mortality. A binary logistic regression was used to identify variables independently associated with mortality. The data was analysed using SPSS.
RESULTS: 336 patients were reviewed as declared COVID-19 positive during the study duration, and 136 were included in the final analysis including 101 males and 35 females. A statistically significant difference in PCT was found between severe and non-severe COVID-19 (p value=0.01); and survivors and nonsurvivors (p value<0.0001). PCT, older age and increased duration of hospital stay were revealed as variables independently associated with mortality. On ROC analysis, an AUC of 0.76 for mortality prediction was generated for PCT.
CONCLUSION: Baseline serum PCT concentration is a promising predictor of mortality and severity in COVID-19 cases when considered in combination with clinical details and other laboratory tests.

Matched MeSH terms: Calcitonin Gene-Related Peptide
Fulltext The α6 subunit-containing GABAA receptor: A novel drug target for inhibition of trigeminal activation

Fan PC, Lai TH, Hor CC, Lee MT, Huang P, Sieghart W, et al.

Neuropharmacology, 2018 09 15;140:1-13.
PMID: 30016665 DOI: 10.1016/j.neuropharm.2018.07.017

Novel treatments against migraine are an urgent medical requirement. The α6 subunit-containing GABAA receptors (α6GABAARs) are expressed in trigeminal ganglia (TG), the hub of the trigeminal vascular system (TGVS) that is involved in the pathogenesis of migraine. Here we reveal an unprecedented role of α6GABAARs in ameliorating TGVS activation using several pharmacological approaches in an animal model mimicking pathological changes in migraine. TGVS activation was induced by intra-cisternal (i.c.) instillation of capsaicin in Wistar rats. Centrally, i.c. capsaicin activated the trigeminal cervical complex (TCC) measured by the increased number of c-Fos-immunoreactive (c-Fos-ir) TCC neurons. Peripherally, it elevated calcitonin gene-related peptide immunoreactivity (CGRP-ir) in TG and depleted CGRP-ir in the dura mater. Pharmacological approaches included a recently identified α6GABAAR-selective positive allosteric modulator (PAM), the pyrazoloquinolinone Compound 6, two α6GABAAR-active PAMs (Ro15-4513 and loreclezole), an α6GABAAR-inactive benzodiazepine (diazepam), an α6GABAAR-selective antagonist (furosemide), and a clinically effective antimigraine agent (topiramate). We examined effects of these compounds on both central and peripheral TGVS responses induced by i.c. capsaicin. Compound 6 (3-10 mg/kg, i.p.) significantly attenuated the TCC neuronal activation and TG CGRP-ir elevation, and dural CGRP depletion induced by capsaicin. All these effects of Compound 6 were mimicked by topiramate, Ro15-4513 and loreclezole, but not by diazepam. The brain-impermeable furosemide antagonized the peripheral, but not central, effects of Compound 6. These results suggest that the α6GABAAR in TG is a novel drug target for TGVS activation and that α6GABAAR-selective PAMs have the potential to be developed as a novel pharmacotherapy for migraine.

Matched MeSH terms: Calcitonin Gene-Related Peptide/metabolism

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