Periventricular hypothalamic cells in the rat brain contain insulin mRNA.

In situ hybridization histochemistry with a 35S-labeled oligodeoxyribonucleotide probe for insulin was performed in the rat. Labeled cells were observed in the pancreas and in the periventricular nucleus of the hypothalamus. No labeling was seen elsewhere in the brain, including the olfactory bulb, the choroid plexus, and the tissue adjacent to the lateral ventricles. This finding suggests that insulin may be released from cells in the periventricular nucleus for transport via cerebrospinal fluid to other brain regions.