The pineal does not concentrate arginine vasotocin from biological fluids in vivo

The ability of the pineal gland to concentrate circulating arginine vasotocin (AVT) from biological fluids in vivo was examined in rats. Intraventricular and intracisternal injections of AVT failed to elevate net pineal AVT content, even though CSF AVT levels were greatly increased by these treatments. Intravenous injection of AVT did elicit a light increase in pineal AVT, but plasma peptide levels wee elevated enormously. Thus, it seems unlikely that an active uptake process for AVT functions in this gland.