Migraine has long been considered as a "vascular headache" but clearly neurological mechanisms are involved. The pathophysiology appears to somehow involve serotonin, both peripherally and centrally, but its involvement may be just epiphenomenal. Adding to the enigma it is apparent that many of the presently available drugs for the treatment of migraine interact in one way or another with serotonin receptors. However, they tend to have a number of other unrelated actions and they are only of limited clinical value. Interestingly a promising new drug for the treatment of the acute attack, sumatriptan, has a very selective action as an agonist at a specific 5-HT1-like receptor sub-type, mediating vasoconstriction, which is localized on cranial blood vessels. Its action may, or may not, be independent of any involvement of serotonin in the genesis of migraine. Hopefully though, current attempts to determine sumatriptan's mechanism of action will shed further light on the pathology of migraine itself and the putative involvement of serotonin.

1 The 5-hydroxytryptamine (5-HT) receptor mediating contraction of endothelium denuded human basilar artery has been characterized in vitro. 2 5-HT and a variety of 5-HT agonists contracted human isolated basilar artery with a rank order of agonist potency, 5-carboxamidotryptamine (5-CT) > 5-HT methysergide > GR43175 > 8-OHDPAT > 2-methyl-5-HT. The maximum response produced by these agonists differed. 3 None of the agonists relaxed human basilar artery when tone was elevated with prostaglandin F2U,, indeed further contraction was seen.4 The contractile responses of human basilar artery to 5-HT and the selective 5-HT1-like agonist GR43175 were highly reproducible whilst those to 5-CT were not. 5 The contractile response to both 5-HT and GR43175 was resistant to antagonism by ketanserin and GR38032, thus excluding activation of 5-HT2 and 5-HT3 receptors. The contractile action of 5-HT and GR43175 was also not antagonized by (±)-cyanopindolol, excluding the activation of receptors similar to 5-HTlA and 5-HTlB recognition sites identified in ligand binding studies. 6 In marked contrast, methiothepin was a potent antagonist of the contractile actions of both 5-HT and GR43175, with a pA2 value of 8.8 against both agonists. Methiothepin (lOOnM) had no effect on the contractile response to the thromboxane A2-mimetic U46619. 7 We conclude that 5-HT and GR43175 contract the human isolated basilar artery by activating the same receptor type. This receptor appears identical to the 5-HT1-like receptor causing contraction of the dog isolated saphenous vein and cerebral blood vessels from the dog and primate.

Integrin ␣ 4 ␤ 1 plays an important role in inflammatory processes by regulating the migration of lymphocytes into inflamed tissues. Here we evaluated the biochemical, pharmacological, and pharmacodynamic properties and efficacy in experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis, of two types of ␣ 4 ␤ 1 inhibitors, the anti-rat ␣ 4 monoclonal antibody TA-2 and the small molecule inhibitor. TA-2 has been extensively studied in rats and provides a benchmark for assessing function. BIO5192 is a highly selective and potent (K D of Ͻ10 pM) inhibitor of ␣ 4 ␤ 1 . Dosing regimens were identified for both inhibitors, which provided full receptor occupancy during the duration of the study.Both inhibitors induced leukocytosis, an effect that was used as a pharmacodynamic marker of activity, and both were efficacious in the EAE model. Treatment with TA-2 caused a decrease in ␣ 4 integrin expression on the cell surface, which resulted from internalization of ␣ 4 integrin/TA-2 complexes. In contrast, BIO5192 did not modulate cell surface ␣ 4 ␤ 1 . Our results with BIO5192 indicate that ␣ 4 ␤ 7 does not play a role in this model and that blockade of ␣ 4 ␤ 1 /ligand interactions without down-modulation is sufficient for efficacy in rat EAE. BIO5192 is highly selective and binds with high affinity to ␣ 4 ␤ 1 from four of four species tested. These studies demonstrate that BIO5192, a novel, potent, and selective inhibitor of ␣ 4 ␤ 1 integrin, will be a valuable reagent for assessing ␣ 4 ␤ 1 biology and may provide a new therapeutic for treatment of human inflammatory diseases.Integrins are a large family of cell surface receptors that mediate cell/cell and cell/matrix interactions and signal transduction. They exist as noncovalent ␣␤ heterodimers of different combinations of ␣ and ␤ chains and share extensive structural homology. The leukocyte integrin ␣ 4 ␤ 1 regulates normal lymphocyte trafficking (Lobb and Hemler, 1994) and provides a key costimulatory signal supporting cell activation (Clark and Brugge, 1995). During inflammatory responses, it regulates lymphocyte migration into the damaged tissues and thus has been recognized as an attractive therapeutic target. In vivo studies using blocking monoclonal antibodies (Lobb and Hemler, 1994) and inhibitory peptides (Molossi et al., 1995) have verified the critical role of ␣ 4 ␤ 1 integrins in leukocyte-mediated inflammation. Numerous EAE models of multiple sclerosis have been designed to recapitulate important aspects of the disease and are responsive to ␣ 4 inhibitors (Yednock et al., 1992). Recent positive phase II data using the anti-␣ 4 antibody 1 Current address: Wyeth, Cambridge, MA.

Background and Purpose-The present study was performed to determine the role of ␣4 (CD49d), a member of the integrin family of adhesion molecules, in ischemic brain pathology. Methods-Male spontaneously hypertensive rats (SHR) or Sprague-Dawley rats underwent 60-minute middle cerebral artery occlusion (MCAO) followed by 23-hour reperfusion. Animals were injected intravenously with 2.5 mg/kg anti-rat ␣4 antibody (TA-2) or isotype control antibody (anti-human LFA-3 IgG 1 , 1E6) 24 hours before MCAO. Infarct volume was quantified by staining of fresh tissue with tetrazolium chloride and myeloperoxidase activity measured in SHR tissue homogenates 24 hours after MCAO. In SHR, mean arterial blood pressure was recorded before and after MCAO in animals treated with TA-2 and 1E6. Fluorescence-activated cell sorting analysis was performed on peripheral blood leukocytes before and after MCAO. Results-TA-2 treatment significantly reduced total infarct volume by 57.7% in normotensive rats (1E6, 84.2Ϯ11.5 mm 3 , nϭ17; TA-2, 35.7Ϯ5.9 mm 3 , nϭ16) and 35.5% in hypertensive rats (1E6, 146.6Ϯ15.5 mm 3 , nϭ15; TA-2, 94.4Ϯ25.8 mm 3 , nϭ11). In both strains, TA-2 treatment significantly reduced body weight loss and attenuated the hyperthermic response to MCAO. In SHR, treatment with TA-2 significantly reduced brain myeloperoxidase activity. Resting mean arterial blood pressure was unaffected by treatment. Leukocyte counts were elevated in TA-2-treated rats. Fluorescence-activated cell sorting analysis demonstrated the ability of TA-2 to bind to CD3ϩ, CD4ϩ, CD8ϩ, and CD11bϩ cells in both naive animals and after MCAO.Conclusions-These data demonstrate that inhibition of ␣4 integrin can protect the brain against ischemic brain injury and implicate endogenous ␣4 integrin in the pathogenesis of acute brain injury. The mechanism by which ␣4 integrin inhibition offers cerebroprotection is independent of blood pressure modulation and is likely due to inhibition of leukocyte function.

The Raman spectra of H2O and D2O ice VIII recovered at ∼100 K and zero pressure have been measured in the range 4000–50 cm−1. The three stretching, three rotational, and four translational bands expected from the symmetry of the crystal have been identified. Two bending bands are expected and have been tentatively identified among some weak bands. The relative intensity of the rotational and stretching bands is much smaller than in the vapor, and so if the intensity of the stretching bands is not greatly changed, the anisotropy of the polarizability is appreciably smaller in ice VIII than in the vapor.