Alteration of cerebral taurine biosynthesis in spontaneously hypertensive rats

Cerebral taurine biosynthesis in a spontaneously hypertensive rat (SHR) has been studied. Cysteine sulfinic acid (CSA) and cysteic acid (CA), possible key intermediates in taurine biosynthesis, were found in the rat brain, whereas no cysteamine-cystamine was detected. In the brain of SHR, a statistically significant decrease in the contents of CSA, CA, and taurine was noted in the cerebellum, hypothalamus, and striatum as compared with normotensive Wistar Kyoto rats. Similarly, it was demonstrated that the activity of cysteine dioxygenase, the enzyme catalyzing cysteine to CSA, was attenuated significantly in the same brain areas of SHR. In contrast, no alteration in the activity of CSA decarboxylase, the enzyme converting CSA to hypotaurine or CA to taurine, was observed. A decline in the percent conversion of [14C]cysteine to [14C]taurine was found also in tissue homogenates from the cerebellum, hypothalamus, and striatum of SHR, indicating that the declines in taurine content may be due to an attenuation of taurine biosynthesis, possibly at the step involving cysteine dioxygenase.