Protein kinase C-inhibition reduces critical weight loss and improves functional outcome after experimental subarachnoid haemorrhage

OBJECTIVES

Subarachnoid haemorrhage (SAH) carries a high burden of morbidity and mortality. One in three patients develop vasospasm, which is associated with Delayed Cerebral Ischemia. The pathophysiology includes vasoconstrictor receptor upregulation in cerebral arteries. The protein kinase C - inhibitor RO-31-7549 reduces the expression of several vasoconstrictor receptors and normalizes cerebral blood flow in experimental SAH but functional and behavioural effects are unknown. This study was undertaken to analyse functional outcomes up to 14 days after experimental SAH.

MATERIALS AND METHODS

54 male rats were randomised to experimental SAH or sham, using the pre-chiasmatic, single injection model, and subsequent treatment or vehicle. 42 remained for final analysis. The animals were euthanized on day 14 or when reaching a humane endpoint. The primary endpoint was overall survival, defined as either spontaneous mortality or when reaching a predefined humane endpoint. The secondary outcomes were differences in the rotating pole test, weight, open field test, novel object recognition and qPCR of selected inflammatory markers.

RESULTS

In the vehicle group 6/15 rats reached the humane endpoint of >20% weight loss compared to 1/14 in the treatment group. This resulted in a significant reduced risk of early euthanasia due to >20% weight loss of HR 0.15 (0.03-0.66, p = 0.04). Furthermore, the treatment group did significantly better on the rotating pole test, RR 0.64 (0.47-0.91, p = 0.02).

CONCLUSION

RO-31-7549 improved outcomes in terms >20% weight loss and rotating pole performance after experimental SAH and could be investigated.

Abstract TP235: Temporal Change Of Brain Mitochondrial Function In A Rodent Model Of Subarachnoid Hemorrhage

Introduction: Subarachnoid hemorrhage (SAH) is a devastating disease. A third of the patients die and a large percentage of the survivors require support in daily living and suffers from reduced quality of life. As part of clinical practice for these patients, a cerebral microdialysis catheter may be placed to monitor cerebral metabolic function. Using this monitoring technique, the patients often demonstrate an increase in the lactate-pyruvate ratio, despite adequate supply of glucose and oxygen, which may be an indirect marker of mitochondrial dysfunction. We wanted to identify a possible mitochondrial dysfunction in a rat SAH model at different time points by directly measuring mitochondrial function in brain tissue ex vivo .

Method: The pre-chiasmatic single injection model of SAH was used. Oroboros Oxygraph high resolution respirometry was used to evaluate the electron transport chain of the mitochondria. We also analyzed ROS generation simultaneously at the same time points using the Oroboros LED2 module. We measured tissue from the cortex and the hippocampus.

Results: 45 rats at four different timepoints, 6-, 24-, 48- and 96 hours after surgery, were included. We identified a significant reduction in respiration through complexes I and II of the electron transport chain in hippocampal tissue at 96 hours after SAH compared to sham. The respiration of cortical tissue at the same time point was reduced compared to sham but did not reach significance. No differences were identified at other time points and no differences in ROS generation were identified.

Conclusion: We conclude that the SAH model can be used as a suitable model to identify mitochondrial dysfunction and that the respiratory capacity of the electron transport chain is reduced in the hippocampus at 96 h post insult in this rat model of SAH.

Rodent behavior following a dural inflammation model with anti-CGRP migraine medication treatment

Background

Migraine is a widespread and prevalent disease with a complex pathophysiology, of which neuroinflammation and increased pain sensitivity have been suggested to be involved. Various studies have investigated the presence of different inflammatory markers in migraineurs and investigated the role of inflammation in inflammatory models with complete Freund's adjuvant (CFA) or inflammatory soup added to the dura mater.

Objective

The aim of the current study was to examine whether application of CFA to the dura mater would cause behavioral alterations that are migraine relevant. In addition, we investigated the potential mitigating effects of fremanezumab, a CGRP (calcitonin gene-related peptide) specific antibody, following CFA application.

Methods

Male Sprague-Dawley rats were randomly divided into six groups: fresh (n = 7), fresh + carprofen (n = 6), fresh + anti-CGRP (n = 6), sham (n = 7), CFA (n = 16), CFA + anti-CGRP (n = 8). CFA was applied for 15 min on a 3 × 3 mm clearing of the skull exposing the dura mater of male Sprague-Dawley rats. We applied the Light/Dark box and Open Field test, combined with the electronic von Frey test to evaluate outcomes. Finally, we observed CGRP immunoreactivity in the trigeminal ganglion.

Results

No differences were observed in the Light/Dark box test. The Open Field test detected behavior differences, notably that sham rats spend less time in the central zone, reared less and groomed more than fresh + carprofen rats. The other groups were not significantly different compared to sham rats, indicating that activation of the TGVS is present in sham surgery and cannot be exacerbated by CFA. However, for the allodynia, we observed specific periorbital sensitization, not observed in the sham animals. This could not be mitigated by fremanezumab, although it clearly reduced the amount of CGRP positive fibers.

Conclusion

CFA surgically administered to the dura causes periorbital allodynia and increases CGRP positive fibers in the trigeminal ganglion. Fremanezumab does not reduce periorbital allodynia even though it reduces CGRP positive fibers in the TG. Further work is needed to investigate whether CFA administered to the dura could be used as a non-CGRP inflammatory migraine model.