Distribution and Regulation of Corticotropinreleasing Factor mRNA in Brain Using in Situ Hybridization Histochemistry

The amino acid sequence of corticotropin-releasing factor (CRF) was established in 1981. A wealth of information has accumulated since on the distribution, pharmacology, and physiology of CRF in the central nervous system and pituitary. The supraoptic nucleus of the rat contains CRF immunoreactivity in oxytocin-containing magnocellular neurons. CRF that is synthesized in the parvocellular neurons of the paraventricular nuclei is transported to the median eminence where it is released into the portal circulation. The function of CRF synthesized by the oxytocin magnocellular neurons is unclear. The chapter describes approach to hybridization histochemistry (ISHH) in detail, and suggests areas for future exploration. The most widely used application of ISHH is for the localization of mRNA species in tissue sections. The chapter focuses on the biosynthesis of CRF by localizing and quantifying the levels of its messenger ribonucleic acid (mRNA) in brain tissues of various species, including man, and after various physiological, pharmacological, and surgical manipulations.