Mitsuhisa Nishiguchi

Antivasospastic and antiinflammatory effects of caspase inhibitor in experimental subarachnoid hemorrhage

OBJECT Inflammation in the subarachnoid space and apoptosis of arterial endothelial cells have been implicated in the development of delayed cerebral vasospasm after subarachnoid hemorrhage (SAH). The authors investigated mechanisms of possible antivasospastic effects of N-benzyl-oxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), a caspase inhibitor that can inhibit both inflammatory and apoptotic systems, in animal models of SAH. METHODS Rabbits were assigned to three groups of eight animals each and were subjected to SAH by injection of blood into the cisterna magna. The experiments were performed in the following groups: SA only, SAH + vehicle, and SAH + Z-VAD-FMK. The Z-VAD-FMK (1 mg) or vehicle (5% dimethyl sulfoxide) was intrathecally administered before SAH induction. Diameters of the basilar artery (BA) were measured on angiograms obtained before and 2 days after SAH. The BA diameter on Day 2 was expressed as a percentage of that before SAH. Interleukin (IL)-1 in the cerebrospinal fluid (CSF) was examined using Western blotting, and brains were immunohistochemically examined for caspase-1 and IL-1beta. In a separate experiment, 20 rats were subjected to SAH and their brains were immunohistochemically assessed for caspase-1, IL-1beta, and macrophages. RESULTS. In rabbits, Z-VAD-FMK significantly attenuated cerebral vasospasm (the BA diameter on Day 2 in SAH-only, SAH + vehicle, and SAH + Z-VAD-FMK groups was 66.6 +/- 3.2%, 66.3 +/- 3.7%, and 82.6 +/- 4.9% of baseline, respectively), and suppressed IL-1beta release into the CSF and also suppressed immunoreactivities of caspase-1 and IL-1P in macrophages infiltrating into the subarachnoid space. Immunoreactivities for caspase-1 and IL-1P were observed in immunohistochemically proven infiltrating macrophages in rats. CONCLUSIONS These results indicate that caspase activation may be involved in the development of SAH-induced vasospasm through inflammatory reaction.

Effect of vasodilation by milrinone, a phosphodiesterase III inhibitor, on vasospastic arteries after a subarachnoid hemorrhage in vitro and in vivo: effectiveness of cisternal injection of milrinone.

OBJECTIVECerebral vasospasm remains a major cause of morbidity and mortality. Milrinone, a bipyridine phosphodiesterase III inhibitor, is a potent member of the inodilator class of cardiac agents for vasospasm and is injected intra-arterially or intracisternally. There have been no studies investigating the duration of action (context-sensitive half-life) of milrinone for vasospasm or the most effective route of administration (intra-arterial versus intracisternal). We examined the effects of intracisternal and intra-arterial injection of milrinone on chronic cerebral vasospasm in dogs. METHODSA double-hemorrhage canine model was used. In a preliminary isometric tension study of canine vasospastic basilar arteries, the vasodilatory effects of milrinone were examined 7 days after an initial injection of blood. Milrinone was injected intracisternally (0.1 mg, 0.47 mmol/L) or intra-arterially (0.3 mg/kg, 1.2 mmol/L), and angiograms were performed 30, 60, 120, 180, 240, 300, and 360 minutes later on day 7. RESULTSMilrinone produced concentration-dependent vasodilation and was effective intracisternally, resulting in significant dilation until 180 minutes after injection and a tendency for dilation until 240 minutes. The effect of intra-arterial injection was not as significant compared with an intracisternal injection, resulting in significant dilation only at 180 minutes after intra-arterial injection. CONCLUSIONIntracisternal injection of milrinone was more effective than intra-arterial injection for chronic cerebral vasospasm in dogs because intracisternal injection produced a higher concentration in vasospastic arteries (0.034–0.068 mmol/L intracisternally versus 0.016 mmol/L intra-arterially).

Effect of deferoxamine-activated hypoxia inducible factor-1 on the brainstem following subarachnoid haemorrhage

Background Hypoxia inducible factor-1 (HIF-1) is a transcription factor that regulates the expression of various neuroprotective genes. The goal of this study was to clarify the relationship between HIF-1α expression and subarachnoid haemorrhage (SAH) and to determine the effects of the deferoxamine (DFO)-induced increase in HIF-1α protein levels on the brainstem and the basilar artery (BA) following experimental SAH.