Postmortem stability of dopamine D₁ receptor mRNA and D₁ receptors

The effects of postmortem interval on dopamine D₁ mRNA and D₁ receptors were assessed in rat striatum under conditions simulating the handling of human brain tissue at 0, 6, 12, and 24 h postmortem. The amount of D₁ mRNA was measured by both in situ hybridization film and emulsion autoradiography with [³⁵S]dATP-labeled oligonucleotide probes. D₁ receptor density was determined by autoradiography with [¹²⁵I]SCH 23982. Neither the total amount of D₁ mRNA in the striatum nor the frequency distribution of striatal cells expressing D₁ mRNA varied with the postmortem interval. There was a modest but significant decrease (ca. 10%) in D₁ receptors over the 24 h postmortem interval; this decrease occurred within the first 6 h postmortem, with no further decreases up to 24 h postmortem. These findings suggest that the effects of postmortem interval on D₁ mRNA and receptors are minimal and should not limit an examination of possible alterations in dopamine D₁ receptor mRNA and D₁ receptors in the postmortem brains of humans with neuropsychiatric disease.