Relevance of prostaglandins in migraine

12: Clinical Aspects of Prostaglandins and Leukotrienes in Migraine

Clinical, pathophysiological, pharmacological, and biochemical evidence support the concept that the prostanoid system may be involved in migraine. As a local defence system prostaglandins may best be linked with hyperalgesia and vascular events. The response to potent inhibitors of PG-synthesis like tolfenamic acid further supports the involvement of prostaglandins in the “inflammatory-like” aspects of migraine pain. The prostanoid system may be closely coupled with the monoaminergic mechanism; e.g. in stress reactions plasma thromboxane correlates with adrenaline levels. The possible participation of leukotrienes in migraine is only speculative. However, in cerebral hypoxia lipid peroxidation is increased and leukotrienes might participate in the cerebrovascular reactions. Prostaglandins may inhibit the formation of free radicals, antagonize some actions of leukotrienes and protect the tissues. The interplay between leukotrienes and prostaglandins may give new aspects to some cerebrovascular abnormalities in migraine.

Prostaglandins in migraine: update

PURPOSE OF REVIEW

This review presents recent findings on the role of prostaglandins in migraine pathophysiology.

RECENT FINDINGS

Experimental studies have shown that prostaglandins are distributed in the trigeminal-vascular system and its receptors are localized in the trigeminal ganglion and the trigeminal nucleus caudalis. Prostaglandins were found in smooth muscles of cranial arteries, and functional studies in vivo showed that prostaglandins induced dilatation of cranial vessels. Human studies showed that intravenous infusion of vasodilating prostaglandins such as prostaglandin E₂ (PGE₂), prostaglandin I₂ (PGI₂) and prostaglandin D₂ (PGD₂) induced headache and dilatation of intra-cranial and extra-cranial arteries in healthy volunteers. In contrast, infusion of non-dilating prostaglandin F₂α (PGF₂α) caused no headache or any vascular responses in cranial arteries. PGE₂ and PGI₂ triggered migraine-like attacks in migraine patients without aura, accompanied by dilatation of the intra-cerebral and extra-cerebral arteries. A novel EP4 receptor antagonist could not prevent PGE₂-induced headache in healthy volunteers.

SUMMARY

Recent in-vitro/in-vivo data demonstrated presence and action of prostaglandins within the trigeminal pain pathways. Migraine induction after intravenous administration of PGE₂ and PGI₂ suggests a specific blockade of their receptors, EP and IP respectively, as a new potential drug target for the acute treatment of migraine.

Evaluation of the use of sumatriptan-naproxen sodium for menstrual migraine and dysmenorrhea

Menstrual migraine (MM) is a form of headache that tends to occur with prolonged, intense and extremely disabling attacks in a short period around the menstrual cycle (usually 2 days before to 3 days after the onset of the menstrual flow). At least 50% of the female migraine population suffers from this subtype of migraine. The possible presence of other perimenstrual pain, such as dysmenorrhea, can make the attacks even more disabling. Since both of these conditions have a common pathological background consisting of a secretion of abnormally high levels of prostaglandins, it can be particularly useful to use a combination of sumatriptan, the progenitor of the triptans and the drug of choice in the treatment of migraine attack, and naproxen sodium, a potent inhibitor of prostaglandin biosynthesis. The combination of sumatriptan 85 mg and naproxen sodium 500 mg has been tested in women suffering from MM and dysmenorrhea, and this combination has been shown to achieve greater satisfaction when compared with placebo. Moreover, sumatriptan-naproxen was also better than placebo in reducing functional disability and improving productivity. The study is discussed in the context of the current state of knowledge about MM treatment.

A role for brain cyclooxygenase-2 and prostaglandin-E2 in migraine: effects of nitroglycerin

Cyclooxygenase-2 (COX-2) may increase prostaglandin E(2) (PGE(2)) production in central nervous system (CNS) and contribute to the severity of pain responses in inflammatory pain. In this chapter, we sought to evaluate the possible role of COX-2 induction and prostaglandins (PGs) synthesis within neuronal areas proposed to be involved in migraine genesis in the animal model of migraine based on the administration of systemic nitroglycerin (NTG). Male Sprague-Dawley rats were injected with NTG (10mg/kg, i.p.) or vehicle and sacrificed 2 and 4h later. The hypothalamus and the lower brain stem were dissected out and utilized for the evaluation of COX-2 expression by means of Western blotting and for the determination of PGE(2) levels by means of ELISA immunoassay. COX-2 expression increased in the hypothalamus at 2h and in the lower brain stem at 4h. PGE(2) levels showed an opposite pattern of change with a decrease in PGE(2) levels at 2h in the hypothalamus and an increase at 4h in the lower brain stem. These data support the hypothesis that NTG administration is capable of activating the COX-2 pathway within cerebral areas. This activity may explain the pronociceptive effect of NTG described in animal and human models of pain. Most importantly, these findings point to mediators and areas that may be relevant for migraine pathogenesis and treatment.

Pirprofen in the treatment of migraine and episodic headache attacks: a placebo-controlled crossover clinical trial

A double-blind, within patient, randomized study to compare the efficacy and tolerability of acute rectal administration of 600 mg pirprofen capsules with matched placebo was carried out in 40 out-patients. They were divided into two groups of 20 patients each according to diagnosis of episodic headache or common or classic migraine. Treatment was given once during each of two consecutive attacks according to a crossover design. None of the patients was withdrawn after randomization. There was a statistically significant difference in favour of pirprofen as regards the preferences expressed by patients at the end of the trial: 34 patients preferred pirprofen, two preferred placebo and four patients had no preference. Pirprofen significantly reduced the duration of headache attack and associated symptoms, but not the peak of pain intensity. Tolerability of the drug was good.

Migraine and the lupus anticoagulant. Case reports and review of the literature

Lupus anticoagulants (LA) are antiphospholipid serum immunoglobulins generally associated with autoimmune conditions, especially systemic lupus erythematosus (SLE). They have recently been linked to thrombotic events, including stroke. A possible association of migraine with LA is now forwarded with the presentation of two cases and a literature review. Our two patients, both in their forties, had migrainous phenomena without SLE or thrombotic events. Eight other cases were found in the literature, suggesting more than a chance association. Relevance to migraine pathophysiology is discussed and may come from the ability of the LA to alter prostaglandins and platelet activity and to interact with neuronal phospholipids. Further, larger studies are needed to support this association.