Insulin increases central apolipoprotein E levels as revealed by an improved technique for collection of cerebrospinal fluid from rats.

Publication Type:

Journal Article

Source:

Journal of neuroscience methods, Volume 209, Issue 1, p.106-12 (2012)

Abstract:

Cerebrospinal fluid (CSF) provides an invaluable analytical window to the central nervous system (CNS) because it reflects the dynamically changing complement of CNS constituents. We describe an improved method for sampling CSF in rats that is easy to perform. It has a 96% success rate of CSF collection and consistently yields large volumes (150-200μl) of CSF. The blood contamination rate is also low (6%) as determined by both visual inspection and the lack of molecular detection of apolipoprotein B, a plasma-derived protein, which is absent in the CNS. This improved method of CSF sampling can have broad applicability in physiological and pharmacological evaluation for diverse CNS targets. We used this technique to provide proof of principle by examining the effect of intraperitoneal insulin on the level of apolipoprotein E (apoE) in the CSF. Insulin (0.5 and 1U/kg) led to a significant increase of insulin in both plasma and CSF at 2h after intraperitoneal administration and decreased blood glucose for at least 2h. ApoE concentrations in CSF, but not in plasma, were also significantly increased, and its time-course was inversely correlated with the alterations in blood glucose over 2h. These results provide a pharmacological validation of the novel CSF sampling and validation procedure for sampling rat CSF.