gms | German Medical Science

Objective: Relaxin is a peptide hormone of the insulin superfamily which has recently been shown to stimulate expression of VEGF in vitro. Once thought to be strictly a reproductive hormone, relaxin has been found to be a potent vasodilatator via NO-mediated mechanisms in many other organs. However, relaxin expression in cerebral vessels has not been studied to date in humans and a deeper understanding of its role in the brain is still lacking. We recently published our data on relaxin expression in pediatric and adult cavernoma and now focus on relaxin expression in adult cerebral cortex arterioles. As clinical trials for the treatment of acute heart failure with relaxin have been promising, we hypothesize that relaxin may even be a new target for treatment of vasospasm and/or ICP therapy.

Methods: Temporal lobe tissue obtained during epilepsy surgery served as controls in a previously published study on pediatric and adult cavernoma. Immunohistochemical staining for Relaxin 1/2/3 and VEGF-R1/R2 were performed. Relaxin 1, 2, and 3 staining was deemed "positive" or "negative" within the endothelium of the veins and arterioles in controls.

Results: A total of n= 5 patients, mean age: 43y; range: 23 – 67y were analyzed. The control specimens were found to have positive relaxin 1 and 3 expression in intraparenchymal arterioles and leptomeningeal arterioles in all 5 cases, respectively. For veins, staining was as follows: relaxin 1: 4/5 positive, relaxin 2: 0/5 positive, relaxin 3: 5/5 positive. In veins, 4/5 cases stained positively for VEGF-R1. In veins, 2/5 cases stained positive for VEGF-R2.

Conclusion: Relaxin 1 and 3 expression in normal human cerebral arterial vasculature is a novel finding and needs further exploration, in particular regarding its binding site, as it may represent a potential target for vasospasm and increased intracranial pressure.