Nat. Med. 10, 524–529 (2004).

Three sentences in this article appeared incorrectly. On p. 524, in the second paragraph after the abstract, the fifth sentence should read “ADP circulates in serum as low-molecular-weight dimers of trimers and high-molecular weight complexes5.” On p. 525, in the first paragraph in the right column, the second sentence should read “We also injected ADP (2 μg/g) or PBS i.v. and measured serum and CSF ADP.” In the second paragraph in the same column, several words were repeated in the second and third sentences; the second sentence should read “ADP (0.1 μg/g, i.c.v.) induced Fos-positive cells in the paraventricular nucleus (PVN; Fig. 2d).”

We regret the errors.