Cerebral Taurine Levels are Associated with Brain Edema and Delayed Cerebral Infarction in Patients with Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Cerebral edema and delayed cerebral infarction (DCI) are common complications after aneurysmal subarachnoid hemorrhage (aSAH) and associated with poor functional outcome. Experimental data suggest that the amino acid taurine is released into the brain extracellular space secondary to cytotoxic edema and brain tissue hypoxia, and therefore may serve as a biomarker for secondary brain injury after aSAH. On the other hand, neuroprotective mechanisms of taurine treatment have been described in the experimental setting. METHODS: We analyzed cerebral taurine levels using high-performance liquid chromatography in the brain extracellular fluid of 25 consecutive aSAH patients with multimodal neuromonitoring including cerebral microdialysis (CMD). Patient characteristics and clinical course were prospectively recorded. Associations with CMD-taurine levels were analyzed using generalized estimating equations with an autoregressive process to handle repeated observations within subjects. RESULTS: CMD-taurine levels were highest in the first days after aSAH (11.2 ± 3.2 µM/l) and significantly decreased over time (p < 0.001). Patients with brain edema on admission or during hospitalization (N = 20; 80 %) and patients developing DCI (N = 5; 20 %) had higher brain extracellular taurine levels compared to those without (Wald = 7.3, df = 1, p < 0.01; Wald = 10.1, df = 1, p = 0.001, respectively) even after adjusting for disease severity and CMD-probe location. There was no correlation between parenteral taurine supplementation and brain extracellular taurine (p = 0.6). Moreover, a significant correlation with brain extracellular glutamate (r = 0.82, p < 0.001), lactate (r = 0.56, p < 0.02), pyruvate (r = 0.39, p < 0.01), potassium (r = 0.37, p = 0.01), and lactate-to-pyruvate ratio (r = 0.24, p = 0.02) was found. CONCLUSIONS: Significantly higher CMD-taurine levels were found in patients with brain edema or DCI after aneurysmal subarachnoid hemorrhage. Its value as a potential biomarker deserves further investigation.

Acoustic startle response, prepulse inhibition, and spontaneous locomotor activity in MPTP-treated mice.

Parkinson's disease (PD) is marked by characterised motor deficits and is accompanied by a severe degeneration of the nigrostriatal dopamine (DA) pathway. It has also been reported that PD patients exhibited additional behavioural deficits, including a deficiency in sensorimotor gating mechanisms. We therefore examined whether the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD in mice could lead to a sensorimotor gating deficit in the prepulse inhibition (PPI) of the acoustic startle response (ASR) paradigm. Two MPTP treatment schedules were separately examined here in male C57BL/6 mice. Post-mortem HPLC analysis confirmed that they were effective in depleting DA in the dorsal striatum (75-88%). PPI was evaluated on days 2, 9 and 16 after the last MPTP treatment; spontaneous locomotor activity was assessed 24 h before each PPI test. No significant change in the expression of PPI was detected across the three time points. On the other hand, the MPTP treatment reduced activity on post-treatment day 1. This effect subsided on post-treatment day 8, and was reversed on day 15. The possibility remains therefore that the reported sensorimotor gating deficits in PD patients might stem from structural or neurochemical aberrations beyond those induced by MPTP treatment.