Melatonin treatment decreases c-fos expression in a headache model induced by capsaicin.

The aim of the present work was to analyze c-fos response within the trigeminal nucleus caudalis (TNC) of pinealectomized rats and animals that received intraperitoneal melatonin, after intracisternal infusion of capsaicin, used to induce intracranial trigeminovascular stimulation. Experimental groups consisted of animals that received vehicle solution (saline-ethanol-Tween 80, 8:1:1, diluted 1:50) only (VEI, n=5); animals that received capsaicin solution (200 nM) only (CAP, n=6); animals submitted to pinealectomy (PX, n=5); sham-operated animals (SH, n=5); animals submitted to pinealectomy followed by capsaicin stimulation (200 nM) after 15 days (PX + CAP, n=7); and animals that received capsaicin solution (200 nM) and intraperitoneal melatonin (10 mg/kg) (CAP + MEL, n=5). Control rats, receiving vehicle in the cisterna magna, showed a small number of c-fos-positive cells in the TNC (layer I/II) as well as the sham-operated and pinealectomized rats, when compared to animals stimulated by capsaicin. On the other hand, pinealectomized rats, which received capsaicin, presented the highest number of c-fos-positive cells. Animals receiving capsaicin and melatonin treatment had similar expression of the vehicle group. Our data provide experimental evidence to support the role of melatonin and pineal gland in the pathophysiology of neurovascular headaches.

Chronic migraine prevention with topiramate.

Chronic migraine (CM) is a disabling condition with not many treatment strategies available. Topiramate is effective in episodic migraine prevention, however little is known about its effect in CM. An open label study was performed. Sixty-four patients diagnosed with CM or probable CM according to the IHS diagnostic criteria were enrolled, 50 patients were available for analysis and an intention-to-treat methodology was applied. The primary endpoint considered was the number of patients with a decrease in headache frequency higher than 50%. The median dose was 100 mg, a reduction in frequency higher than 50% occurred in 33 patients (66%) and 14 (28%) presented a complete response, defined as a frequency reduction higher than 95%. The medication was well tolerated. The most common side effects found were weight loss, paraesthesias, nausea, cognitive dysfunction, fatigue, somnolence, insomnia and depression. Our findings suggest that topiramate is effective in CM prophylaxis.