Transient expression of somatostatin mRNA in the auditory system of neonatal rat.

Postnatal changes of preprosomatostatin mRNA expression in the rat auditory system were examined using in situ hybridization histochemical techniques. It was found that during postnatal days 1 and 2 most of the neurons in the dorsal and ventral cochlear nuclei, and large numbers of neurons in the inferior colliculus, paralemniscal nucleus, and lateral lemniscal nucleus, expressed somatostatin mRNA with a strong intensity. During postnatal development a marked decrease in the number and intensity of neurons expressing somatostatin mRNA was seen. These findings suggested that somatostatin was actively produced in the cochlear nuclei at a very early stage but that production later became reduced or ceased during postnatal ontogeny.