Phosphodiesterase 3 and 5 and cyclic nucleotide-gated ion channel expression in rat trigeminovascular system.
ABSTRACT Activation of the trigeminovascular pain signalling system appears involved in migraine pathophysiology. However, the molecular mechanisms are only partially known. Stimulation of cAMP and cGMP production as well as inhibition of their breakdown induce migraine-like headache. Additionally, migraine may be associated with mutations in ion channels. The aim of the present study was to describe the expression of phosphodiesterase 3 (PDE3) and 5 (PDE5) and cyclic nucleotide-gated ion channels (CNG) in cerebral arteries, meninges, and the trigeminal ganglion. mRNA for PDE and CNG was determined in the rat middle cerebral artery, basilar artery, trigeminal ganglion, and dura mater using real-time PCR. PDE and CNG proteins were identified using Western blot. For comparison, rat aorta and mesenteric artery were analysed. PDE3A, PDE3B, and PDE5A mRNA were detected in all tissues examined except for PDE3A mRNA in dura mater and the trigeminal ganglion. PDE5A and PDE3A protein expression was present in both cerebral and peripheral arteries, whereas PDE3B protein was present only in the cerebral arteries. The CNGA4 and B1 subunit mRNAs were detected in cerebral arteries and CNGA2 also in the mesenteric artery. CNGA2 and A3 proteins were found in cerebral arteries and dura and CNGA1, CNGA2 and CNGA3 in the trigeminal ganglion. In conclusion, PDE3A, PDE3B, PDE5A, and five CNG subunits were expressed in several components of the trigeminovascular system of the rat. This suggests that modulation of cAMP and cGMP levels by PDE and activation of CNG may play a role in trigeminovascular pain signalling leading to migraine headache.
- SourceAvailable from: Christina Kruuse[show abstract] [hide abstract]
ABSTRACT: Migraine is considered a neurovascular disease involving dilatation of cerebral arteries. Nitric oxide (NO) donors induce dilatation of cerebral and extracranial arteries and migraine, but NO has several mechanisms of action in addition to its cyclic guanosine monophosphate (cGMP)-mediated vasodilatation. We examined whether sildenafil (Viagra), a selective inhibitor of cGMP-hydrolysing phosphodiesterase 5 (PDE5), which acts exclusively by increasing cGMP, can induce migraine and dilatation of cerebral arteries. We included 12 patients with migraine without aura in this double-blind, placebo-controlled crossover study, in which placebo or sildenafil 100 mg was administered orally on two separate days. Blood flow velocity in the middle cerebral artery (V(mca)) was recorded by transcranial Doppler ultrasonography and regional cerebral blood flow in the territory of the middle cerebral artery (rCBF(mca)) was measured using SPECT (single photon emission computed tomography) and xenon 133 inhalation. Radial and temporal artery diameters were studied using high-frequency ultrasonography. Headache response, tenderness of pericranial muscles, blood pressure and heart rate were measured repeatedly. We found that migraine attack was induced by sildenafil in 10 of 12 migraine patients and by placebo in two of 12 patients (P = 0.01). V(mca) (P = 0.1) and rCBF(mca) (P = 0.93) remained unchanged after sildenafil. Temporal (P = 0.47) and radial (P = 0.87) artery diameter and pericranial tenderness (P = 0.16) were unaffected by sildenafil. Systolic and diastolic blood pressures were unchanged but heart rate increased from a mean of 62 +/- 2 to 74 +/- 3 beats/min (P = 0.01) after sildenafil. Our results demonstrate that migraine may be induced via a cGMP-dependent mechanism, and we show for the first time that this occurs without initial dilatation of the middle cerebral artery. We propose that triggering mechanisms may reside within the perivascular sensory nerve terminals or the brainstem. However, other sites of action may also be possible and future studies are needed to elucidate this. In the clinical use of sildenafil, patients who have migraine should be informed about the risk of migraine attacks.Brain 02/2003; 126(Pt 1):241-7. · 9.92 Impact Factor
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ABSTRACT: Despite evidence emerging from the experimental model of nitroglycerin-induced headache, the endogenous increase in nitric oxide (NO) production during migraine attacks is only speculative. It has been hypothesized that there is a close relationship between activation of the L-arginine/NO pathway and production of certain vasoactive and algogenic prostaglandins during spontaneous migraine attacks, but this suggestion also needs to be confirmed. In the present study the levels of nitrites, the stable metabolites of NO, were determined with high performance liquid chromatography (HPLC) in the internal jugular venous blood of five patients affected by migraine without aura examined ictally. These samples were taken within 30 min, 1, 2, and 4 h from the onset of the attack and at the end of the ictal period. At the same time, the plasma levels of calcitonin gene-related peptide (CGRP), neurokinin A (NKA), prostaglandin E2 (PGE2) and 6 keto PGF1alpha, the stable product of PGI2, were assessed with radioimmunoassay (RIA) kits in the same samples. The levels of the intracellular messengers, cGMP and cAMP, were also measured with the RIA method. Nitrite, cGMP, CGRP and NKA levels reached their highest values at the first hour, then they tended to decrease progressively and returned, after the end of attacks, to values similar or below those detected at the time of catheter insertion (ANOVA, statistical significance: P<0.001; P<0.002; P<0.002; P<0.003, respectively). PGE2 and 6 keto PGF1alpha, as well as cAMP levels also significantly increased at the first hour but reached a peak at the 2nd hour and remained in the same range until the 4th and 6th hours. Then their values tended to decrease after the end of attacks, becoming lower than those measured immediately after catheter positioning for internal jugular venous blood drawing (ANOVA: P<0.002, P<0.004, P<0.001, respectively). Our results support early activation of the L-arginine/NO pathway which accompanies the release of vasoactive peptides from trigeminal endings and a late rise in the synthesis of prostanoids with algogenic and vasoactive properties which may intervene in maintaining the headache phase.Cephalalgia 12/2000; 20(10):907-18. · 3.49 Impact Factor
Chapter: Cyclic Nucleotide‐gated Ion ChannelseLS, 04/2001; , ISBN: 9780470015902