Sensitive and Nonradioactive

In situ hybridization, a unique method for evaluating gene expression, allows nucleic acid sequences to be detected in morphologically preserved chromosomes, intact cells, and tissue sections. The localized sequences within the cells can be viewed in relation to the morphological features of tissue sections, thus permitting anatomically meaningful interpretations of gene activity. In neurobiology, in situ hybridization is a commonly used sensitive technique to identify, localize, and study regulation of mRNA expression for neurotrophins or neural growth factors in tissue sections. Neurotrophins, such as nerve growth factor (NGF), neurotrophin-3 (NT-3), and brain-derived neurotrophic factor (BDNF), are neurotrophic factors produced by effector tissues, neurons, and glial cells, and regulate differentiation, survival, and functions of neurons in the central and peripheral nervous systems. Functional roles of neurotrophins are often closely related to their gene expression during development. Detection of their mRNA expression in developing and in experimental animals has accumulated considerable data revealing many biological functions of these molecules in the normal development and in pathological conditions of the nervous system (1 ,2 ).