Somatostatin gene expression in the developing monkey frontal and cerebellar cortices

Somatostatin (SRIF) mRNA was determined in the developing monkey frontal and cerebellar cortices by the dot blot and the northern blot analyses at embryonic day 120 (E120), embryonic day 140 (E140), newborn stage (Nb), postnatal day 60 (P60) and adult stage (Ad.) At E120, at which time the migration of the cortical neurons had already been completed, SRIF mRNA was detectable with 50% of the maximal value at E140 in the cerebral frontal cortex (von Bonin and Bailey's area FD). After E140, the level of mRNA gradually declined to the adult level by P60 with 25% of the maximal value. In the cerebellum, SRIF mRNA was highly expressed at E120. The level decreased to 18% of the maximum at E140. Between the newborn and adult stages, there existed no positive signal of the mRNA. In contrast, both fetal and adult liver tissues contained no amounts of SRIF mRNA. We discussed the physiological meanings of the enhanced SRIF gene expression in the developing monkey cerebral and cerebellar cortices.