Topical dura mater application of CFA induces enhanced expression of c-fos and glutamate in rat trigeminal nucleus caudalis: attenuated by KYNA derivate (SZR72).

BACKGROUND: Migraine is a debilitating neurological disorder where trigeminovascular activation plays a key role. We have previously reported that local application of Complete Freund's Adjuvant (CFA) onto the dura mater caused activation in rat trigeminal ganglion (TG) which was abolished by a systemic administration of kynurenic acid (KYNA) derivate (SZR72). Here, we hypothesize that this activation may extend to the trigeminal complex in the brainstem and is attenuated by treatment with SZR72. METHODS: Activation in the trigeminal nucleus caudalis (TNC) and the trigeminal tract (Sp5) was achieved by application of CFA onto the dural parietal surface. SZR72 was given intraperitoneally (i.p.), one dose prior CFA deposition and repeatedly daily for 7 days. Immunohistochemical studies were performed for mapping glutamate, c-fos, PACAP, substance P, IL-6, IL-1ß and TNFα in the TNC/Sp5 and other regions of the brainstem and at the C1-C2 regions of the spinal cord. RESULTS: We found that CFA increased c-fos and glutamate immunoreactivity in TNC and C1-C2 neurons. This effect was mitigated by SZR72. PACAP positive fibers were detected in the fasciculus cuneatus and gracilis. Substance P, TNFα, IL-6 and IL-1ß immunopositivity were detected in fibers of Sp5 and neither of these molecules showed any change in immunoreactivity following CFA administration. CONCLUSION: This is the first study demonstrating that dural application of CFA increases the expression of c-fos and glutamate in TNC neurons. Treatment with the KYNA analogue prevented this expression.

Brainstem and thalamic projections from a craniovascular sensory nervous centre in the rostral cervical spinal dorsal horn of rats.

To examine the ascending projections from the headache-related trigeminocervical complex in rats, biotinylated dextran amine (BDA) was injected into the ventrolateral dorsal horn of segments C1 and C2, a region previously demonstrated to receive input from sensory nerves in cranial blood vessels. Following injections into laminae I-II, BDA-labelled terminations were found bilaterally in several nuclei in the pons and the midbrain, including the pontine reticular nucleus, the parabrachial nuclei, the cuneiform nucleus and the periaqueductal grey. In the diencephalon, terminations were confined to the contralateral side and evident foremost in the posterior nuclear group, especially its triangular part, and in the ventral posteromedial nucleus. Following injections extending through laminae I-IV, anterograde labelling was more extensive. Some of the above regions are likely to be involved in the central processing of noxious signals of craniovascular origin and therefore putatively involved in mechanisms associated with primary headaches.

Sympathetic activation after two weeks of nifedipine treatment in primary Raynaud's patients and controls.

The effect of a standardized cold pressor test on circulating noradrenaline and neuropeptide-Y-like immunoreactivity was investigated in 12 women with primary Raynaud's phenomenon and 12 healthy female controls before and after 2 weeks of treatment with the calcium antagonist, nifedipine. Measurement before treatment showed significant increase during the cold pressor test on circulating noradrenaline in both the primary Raynaud's phenomenon group and in the control group (from 0.29 +/- 0.15 ng/ml to 0.33 +/- 0.16 ng/ml, p < 0.05, and from 0.21 +/- 0.14 ng/ml to 0.29 +/- 0.16 ng/ml, p < 0.005, respectively). However, treatment with nifedipine resulted in significantly increased levels of circulating noradrenaline during the cold pressor test only in the control group (from 0.43 +/- 0.21 ng/ml to 0.50 +/- 0.20 ng/ml, p < 0.01). Plasma concentrations of neuropeptide-Y-like immunoreactivity were unchanged by the standardized cold pressor test, whether performed before or during nifedipine treatment in both groups. Nifedipine treatment per se significantly increased circulating noradrenaline in both the primary Raynaud's phenomenon patient group and in the control group (from 0.29 +/- 0.15 to 0.49 +/- 0.13 and 0.21 +/- 0.14 to 0.43 +/- 0.21 ng/ml, respectively, p < 0.001). Similarly, the circulating neuropeptide-Y-like immunoreactivity significantly increased in both the primary Raynaud's phenomenon group and in the control group (from 105 +/- 21 to 137 +/- 19 pmol/l and 107 +/- 17 to 147 +/- 13 pmol/l, respectively, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of cold pressor test on circulating atrial natriuretic peptide 99-126 (ANP) in patients with Raynaud's phenomenon and influence of treatment with magnesium sulphate and nifedipine.

The effect of a standardized cold pressure test (CPT) on the venous concentration of immunoreactive atrial natriuretic peptide (irANP) was studied in 12 females with primary Raynaud's phenomenon (PRP) and 12 female age-matched controls. The test was performed at the end of three stages. During the first stage no medication was given. During the second stage a magnesium infusion was given. After fourteen days of medication with a calcium antagonist (Nifedipine) the third stage of the study was performed. The venous irANP increased significantly (P < 0.05) 10 min after the start of the CPT both in the PRP group and in the control group (136 +/- 39 to 159 +/- 54 and 153 +/- 45 to 179 +/- 40 pg ml-1, given as mean and SD). Baseline irANP did not change in the PRP group after treatment with magnesium or nifedipine. In the control group nifedipine treatment significantly (P < 0.01) lowered venous irANP compared to the no treatment or magnesium sulphate infusion stages (128 +/- 31 vs. 153 +/- 45 and 160 +/- 41 pg ml-1). After the CPT in both PRP group and control group the venous irANP did not increase either during magnesium sulphate infusion or nifedipine treatment. In conclusion the study has demonstrated that a standardized CPT results in a delayed increase in irANP in venous plasma and that magnesium sulphate infusion and nifedipine treatment prevent this increase. Furthermore, our data do not suggest a role for irANP in the symptomatology of primary Raynaud's phenomenon.

Effect of pregnancy and sex steroids on alpha 1-adrenoceptor mechanisms in the guinea-pig uterine vascular bed.

Adrenoceptor mechanisms in the extrinsic uterine arteries from late pregnant guinea-pigs were characterized pharmacologically and compared with contractile responses of uterine arteries from non-pregnant and oophorectomized control, progesterone and oestrogen treated animals. Pregnancy caused an increase in diameter of the arteries, more pronounced the more distal they were. There was no change in potassium-evoked maximum contractions during pregnancy. Noradrenaline (10 nM to 1 mM), in the presence of cocaine (1 microM) and propranolol (0.1 microM), induced concentration-dependent contractions of the arterial segments, with approximately similar pD2 values. The maximum responses (Emax) were significantly increased during pregnancy and hormone supplementation. Prazosin (10 nM to 1 microM), but not rauwolscine (10 nM to 1 microM), antagonized noradrenaline-evoked contractions of the arteries. Isoprenaline (10 nM to 1 microM), in the presence of prazosin (0.1 microM) and cocaine (1 microM), had no relaxant effect on arteries contracted submaximally by prostaglandin F2a (5 microM). Neither cocaine nor normetanephrine modified noradrenaline-evoked contractions of the uterine artery. The results indicate that guinea-pig uterine vasoconstriction is mediated by alpha 1-adrenoceptors while relaxant beta-adrenoceptor effects, neuronal and extraneuronal uptake mechanisms are of minor importance. The observed increase in Emax may be due either to an increase in the number of alpha 1-adrenoceptors or to an enhanced pharmaco-mechanical coupling, which conceivably is regulated by sex steroids since this response was reproduced in castrated animals by hormone supplementation.

Calcium antagonists: effects on cerebral blood flow and blood-brain barrier permeability in the rat.

1 Because they affect isolated cerebral arteries, some calcium antagonists have been studied on the intact cerebral circulation of the rat.2 Global cerebral blood flow ((133)Xe clearance technique) was measured in anaesthetized rats. Neither perhexiline (0.1 mug/kg to 1.0 mg/kg, i.v.) nor diltiazem (0.06-0.6 mg/kg, i.v.) had any significant effect on resting cerebral blood flow when measured 5 min after each dose. A high dose of nifedipine (1.0 mg/kg, i.v.) was administered during induced hypocapnia. Nifedipine failed to modify the hypocapnic vasoconstriction of the cerebral vasculature when compared to vehicle-treated rats.3 The possibility of discrete changes in regional cerebral blood flow was investigated. Local cerebral blood flow was measured in a number of brain regions by the [(14)C]-ethanol technique 15 min after the administration of nifedipine (20 or 100 mug/kg, i.v.). Nifedipine had no apparent effect on regional blood flow in the rat brain.4 Acute arterial hypertension increases protein leakage into the brain, a phenomenon susceptible to drugs that act on endothelial pinocytosis which is known to be calcium-dependent. The increase in protein extravasation, induced by the intravenous administration of either angiotensin II or adrenaline, was unchanged in rats previously treated with either nimodipine (20 mug/kg, i.v.) or nifedipine (50 mug/kg, i.v.) when dissolved in ethanol alone. However, nifedipine (20 mug/kg, i.v.) when dissolved in a solution of polyethylene glycol and ethanol further enhanced the hypertension-induced increase in brain albumin permeability.5 In conclusion, we have been unable to demonstrate any apparent effects of various calcium antagonists on the intact cerebral circulation of the rat, despite the number of different experimental models used.

Regional distribution of mast cells containing histamine, dopamine, or 5-hydroxytryptamine in the mammalian brain.

Brain mast cells were studied in mice, rats, rabbits, hamsters, guinea pigs, cats, cows, monkeys, and humans with use of a variety of techniques. They were localized by staining with Astrablau or by toluidine blue-induced metachromasia and characterized by their ultrastructural appearance and by the presence of histochemically demonstrable histamine (o-phthaldiadehyde fluorescence method). The identity of the fluorophore was secured by microspectrofluorometry. Mast cells in brain usually had a perivascular localization but were also found scattered in the parenchyma. The regional variations in the number of mast cells agreed with the histamine concentration as measured fluorometrically. The variation was in the order leptomeninges greater than hypothalamus greater than cerebral cortex = mesencephalon greater than cerebellum = brain stem. In addition to histamine, murine mast cells stored serotonin, whereas bovine mast cells contained dopamine, visualized histochemically by the formaldehyde technique.