AH RECEPTOR IN DIFFERENT TISSUES OF C57BL 6J AND DBA/2J MICE - USE OFCOMPETITIVE POLYMERASE CHAIN-REACTION TO MEASURE AH-RECEPTOR MESSENGER-RNA EXPRESSION/

A competitive polymerase chain reaction (PCR) method was used to deter mine the Ah-receptor mRNA content in several tissues of 2,3,7,8-tetrac hlorodibenzo-p-dioxin (TCDD)-sensitive C57BL/6J and less susceptible D BA/2J mice. Total RNA from liver, lung, thymus, spleen, heart, kidney, brain, muscle, and placenta was isolated and reverse-transcribed. Eac h cDNA was coamplified with a known amount of homologous competitor fr agment, and PCR products were quantified by extrapolating against a st andard curve. The Ah-receptor mRNA was expressed in all tissues examin ed. The highest mRNA level was found in lung, yielding concentrations of 31.7 +/- 11.0 X 10(3) molelcules/100 ng RNA and 20.3 +/- 8.9 X 10(3 ) molecules/100 ng RNA in C57BL/6J and DBA/2J mice, respectively. In h eart, liver, thymus, brain, and placenta the Ah-receptor mRNA content was about 5-10 times lower than in lung. Low levels were found in sple en, kidney, and muscle. Statistical analysis of the data revealed no s ignificant differences regarding the Ah-receptor mRNA expression betwe en C57BL/6J and DBA/2J mice. From these results it is suggested that f actors other than differences in Ah-receptor mRNA content may be respo nsible for different susceptibility of C57BL/6J and DBA/2J mice toward TCDD. (C) 1994 Academic Press, Inc.