Ontogeny of dopamine D 2 receptor mRNA in rat brain

Abstract

The postnatal development of rat brain dopamine D 2 receptor gene expression was investigated in animals 1 day to 1 year old. The level of expression of the striatal D 2 mRNA was appreciable at birth (day 1), steadily increased to a maximum at day 28, and showed declines at ages 6 months and one year. The mRNA development profile was similar to that of [ 3H]spiroperidol binding in striatal membranes except that there was a lack of correlation between mRNA levels and [ 3H]spiroperidol binding during the early developmental periods. For example, although the mRNA expression at day 1 is about 75% of the 28-day value, the corresponding level of [ 3H]spiroperidol binding is only 15% of the value observed at day 28. Polymerase chain reaction (PCR) analysis of alternatively spliced forms of D 2 receptor mRNA showed that the developmental expression of the two isoforms proceeded in parallel as the ratio of D 21 and D 25 mRNAs remained more or less constant in different age group of rats. In situ hybridization revealed a differential developmental profile of D 2 mRNA for major dopaminergic regions of rat brain such as caudate putamen, nucleus accumbens, olfactory tubercle and substantia nigra.