Effect of Progesterone on Cerebral Vasospasm and Neurobehavioral Outcomes in a Rodent Model of Subarachnoid Hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) induces widespread inflammation leading to cellular injury, vasospasm, and ischemia. Evidence suggests that progesterone (PROG) can improve functional recovery in acute brain injury owing to its anti-inflammatory and neuroprotective properties, which could also be beneficial in SAH. We hypothesized that PROG treatment attenuates inflammation-mediated cerebral vasospasm and microglial activation, improves synaptic connectivity, and ameliorates functional recovery after SAH. METHODS: We investigated the effect of PROG in a cisternal SAH model in adult male C57BL/6 mice. Neurobehavioral outcomes were evaluated using rotarod latency and grip strength tests. Basilar artery perimeter, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptor 1 (GluR1)/synaptophysin colocalization, and Iba-1 immunoreactivity were quantified histologically. RESULTS: PROG (8 mg/kg) significantly improved rotarod latency at day 6 and grip strength at day 9. PROG-treated mice had significantly reduced basilar artery vasospasm at 24 hours. GluR1/synaptophysin colocalization, indicative of synaptic GluR1, was significantly reduced in the SAH+Vehicle group at 24 hours, and PROG treatment significantly attenuated this reduction. PROG treatment significantly reduced microglial cell activation and proliferation in cerebellum and cortex but not in the brainstem at 10 days. CONCLUSIONS: PROG treatment ameliorated cerebral vasospasm, reduced microglial activation, restored synaptic GluR1 localization, and improved neurobehavioral performance in a murine model of SAH. These results provide a rationale for further translational testing of PROG therapy in SAH.

Intranasal administration of E-selectin to induce immunological tolerization can suppress subarachnoid hemorrhage-induced vasospasm implicating immune and inflammatory mechanisms in its genesis.

Evidence that inflammatory and immune mechanisms may have a critical role in the development of vasospasm after subarachnoid hemorrhage is accumulating. We examined, therefore, whether induction of immunological tolerance to the adhesion molecule that is uniquely expressed on activated endothelium, E-selectin, could inhibit the vasospasm provoked by subarachnoid blood in a rat subarachnoid hemorrhage model. We found that intranasal instillation of E-selectin every other day for 10 days on a mucosal tolerization schedule suppressed delayed type hypersensitivity to E-selectin confirming tolerance to that molecule and markedly suppressed basilar artery spasm after subarachnoid hemorrhage. The results of this proof-of-concept study suggest that agents that can mimic the local effects of the mediators of mucosal tolerance could have therapeutic potential for the management of post-subarachnoid hemorrhage vasospasm.

Quantitative analysis of gene expressions related to inflammation in canine spastic artery after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: The possible role of inflammatory reaction of the cerebral artery in the pathogenesis of cerebral vasospasm has been noted in recent studies. We quantitatively measured the levels of expression of genes related to inflammation in the spastic artery in a canine double-hemorrhage model. METHODS: Twenty dogs were assigned to 4 groups: group D0, control; group D2, dogs killed 2 days after cisternal injection of blood; group D7, dogs given double cisternal injections of blood and killed 7 days after the first injection; and group D14. Angiography was performed twice: on the first day and before the animals were killed. Total RNA was extracted from the basilar artery. The expressions of interleukin (IL)-1alpha, IL-6, IL-8, IL-10, tumor necrosis factor-alpha, E-secretin, fibronectin, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule-1, transforming growth factor-ss, basic fibroblast growth factor, and collagen types I, III, and IV were examined with TaqMan real-time quantitative reverse transcription-polymerase chain reaction. RESULTS: Prolonged arterial narrowing peaking on 7 day was observed. There was a significant difference in vessel caliber between D0, D2, D7, and D14 groups (P:<0.0001). There were significant differences in mRNA expression in the basilar artery for IL-1alpha, IL-6, IL-8, ICAM-1, and collagen type I between D0, D2, D7, and D14 groups (P:=0.0079, 0. 0196, 0.0040, 0.0017, and <0.0001, respectively). The average level of mRNA was highest in D7 for IL-1alpha, IL-6, IL-8, and ICAM-1 (17-, 16-, 131-, and 1.7-fold compared with those of D0, respectively) and in D14 for collagen type I (10.9-fold). CONCLUSIONS: Increased expression of genes related to inflammation in the spastic artery suggests that inflammatory reaction of the cerebral artery is associated with sustained contraction.

Inflammation and intracranial aneurysms.

OBJECTIVE: An intracranial aneurysm is an important acquired cerebrovascular disease that can cause a catastrophic subarachnoid hemorrhage. Despite modern therapy, most patients die or are left disabled as a direct result of a severe initial hemorrhage. The development of more effective treatment strategies depends on understanding the fundamental biology of cerebral aneurysms. The purpose of the present study is to determine whether inflammation or immunological reaction occurs in cerebral aneurysms. METHODS: Aneurysm tissue was collected at the time of microsurgical repair from 23 unruptured and 2 ruptured aneurysms (25 patients) and compared with 11 control basilar arteries harvested at autopsy. Immunohistochemistry was used to localize complement (C3c, C9), immunoglobulins (IgG, IgM), vascular cell adhesion molecule-1, macrophages and monocytes (CD68), T lymphocytes (CD3), and B lymphocytes (CD20). RESULTS: Complement (C3c, P < 0.0001; C9, P = 0.0017), immunoglobulin (IgG, P = 0.0013; IgM, P = 0.031), vascular cell adhesion molecule-1 (P = 0.0022), macrophages (CD68, P = 0.004), and T lymphocytes (CD3, P = 0.0004) were all frequently present in the wall of aneurysm tissue but were rarely identified in control basilar arteries. A few B lymphocytes (CD20, P = 0.41) were found in aneurysm tissue, but none were found in the basilar arteries. CONCLUSION: Extensive inflammatory and immunological reactions are common in unruptured intracranial aneurysms and may be related to aneurysm formation and rupture.

Systemic complement depletion inhibits experimental cerebral vasospasm.

OBJECTIVE: Cerebral vasospasm is the leading cause of morbidity and mortality in patients who are hospitalized because of aneurysmal subarachnoid hemorrhage (SAH). Recent work has suggested that activation of the complement cascade contributes to the development of cerebral vasospasm. To further examine this hypothesis, a rabbit model of SAH was employed. METHODS: Two milliliters of autologous arterial blood was injected into the region of the perimesencephalic cistern. Forty-eight hours after SAH was induced, intravital perfusion-fixation was performed. Morphometric analysis of the basilar artery was used to assess the extent of cerebral vasospasm after pretreatment with the complement depleting agent, cobra venom factor (CVF), or vehicle. Rabbits were randomized to one of four groups: 1) sham (n = 5); 2) sham + CVF (n = 4); 3) SAH (n = 10); or 4) SAH + CVF (n = 7). Twenty-four hours before induction of SAH, the animals received either 100 units/kg CVF or vehicle. The total hemolytic potential of the serum confirmed a significant (P < 0.05) reduction in serum complement activity 24 hours after the administration of CVF. RESULTS: Pretreatment with CVF significantly (P < 0.0083) reduced the extent of vasospasm, as assessed by lumen diameter from 393.9 +/- 100.1 microns (mean +/- standard deviation) in the SAH group to 510.7 +/- 72.8 microns in the SAH + CVF group, when compared with the sham (594.5 +/- 27.9 microns) and sham + CVF (587.7 +/- 47.3 microns) groups. CONCLUSION: The results suggest a role for complement activation in SAH.

Expression of intercellular adhesion molecule 1 (ICAM-1) on the cerebral artery following subarachnoid haemorrhage in rats.

In order to study how immune-inflammatory responses are involved in the pathogenesis of cerebral vasospasm after subarachnoid haemorrhage (SAH), the kinetics of expression of the intercellular adhesion molecule 1 (ICAM-1), a ligand for the leucocyte adhesion receptor, were studied on the cerebral arteries following SAH in rats. The SAH was induced by intracisternal injection of arterial blood. The rats were sacrificed at specified times: immediately after induction of SAH to seven days after SAH. Cryostat sections of the basilar artery (BA) were prepared and incubated with anti-rat ICAM-1 antibody. Morphometric analysis of the BA revealed a significant narrowing of the luminal diameter on Day 2 following SAH. While in the non-treated normal animals, no nor only weak expression of ICAM-1 was observed on the endothelial layer of the BA, there was greater expression of ICAM-1 on the endothelial layer of the BA in SAH rats, and the expression was observed also in the medial layer of the artery from Day 2 to Day 5 following SAH. The present results indicate that SAH really causes responses in the cellular immunity not only in the endothelial layer, but also in the medial layer of the artery as a target of immune damage, which is presumed to be one of the important steps in the development of cerebral vasospasm.

Changes of neuropeptide immunoreactivity in cerebrovascular nerve fibers after experimentally produced SAH. Immunohistochemical study in the dog.

The immunoreactivity of vasoactive intestinal polypeptide (VIP)-, substance P (SP)-, and neuropeptide Y (NPY)-containing nerve fibers in the basilar artery (BA) and proximal portion of the middle cerebral artery (M1) was immunohistochemically examined in the dog after experimentally produced subarachnoid hemorrhage (SAH). The SAH was produced by a single injection of fresh autologous arterial blood (1 ml/kg body weight) into the cisterna magna. The density (the averaged number of nerve fibers in a unit area) of VIP-, SP-, and NPY-immunoreactive perivascular nerve fibers in the M1 segment and the BA was markedly decreased (5% to 40% of the normal value) immediately after the injection. The density of VIP- and SP-immunoreactive perivascular fibers increased 2 or 3 weeks after SAH and became normal by the 63rd day after injection. On the other hand, no substantial recovery was observed in the density of NPY-immunoreactive perivascular fibers by 63 days after injection.