FIGURE 5.

CTRP4 is produced and secreted by neurons. A, the Ctrp4 transcript is highly expressed in primary rodent neurons, and the entire coding region of the cDNA can be readily amplified by PCR. B, real-time PCR analysis of Ctrp4 expression in isolated primary rat neurons versus astrocytes. The expression level was normalized to rat β-actin. C, detection of CTRP4 protein in the cell lysate of isolated primary neurons by immunoblot analysis using a CTRP4-specific antibody. D, detection of secreted CTRP4 in the conditioned medium of primary cortical and hippocampal neurons by immunoblot analysis. Medium was harvested on days 2, 7, 10, and 14. DIV, days in vitro. Molecular weight markers are indicated on the left of each immunoblot analysis.