Abstract
Oxytocin- and vasopressin-producing magnocellular
neurons (MCNs) of the hypothalamo-neurohypophysial system are the
only neuronal phenotypes present in the rat supraoptic nucleus
(SON). Laser microdissection of the SON, extraction and T7-based
amplification of its RNAs, and analysis of the resulting cDNAs by
hybridization on a 35, 319 element DNA microarray have provided a
detailed composite view of the gene expression profile of the
MCNs. The genes expressed in the SON were compared with those
expressed in a reference tissue consisting of total hypothalamus,
and this "expression ratio" indicated which genes were
preferentially expressed in the SON. Of the 26,000 unique genes
on the array, 1385 were found to be expressed in the SON at
levels more than two times greater than in the hypothalamus as a
whole. Of these, 123 were expressed
3.4-fold higher in the SON versus
hypothalamus. Most of these preferentially expressed genes were
not previously known to be expressed in the MCNs. Quantitative
and double-label in situ hybridization histochemistry was
used selectively to confirm a number of these microarray
observations and to evaluate the osmotic regulation and
cell-specific expression of these genes, respectively.
Key words: oxytocin; vasopressin; hypothalamus; gene expression; microarray; laser microdissection