Identification of alpha 2 adrenergic receptor gene expression in sympathetic neurones using polymerase chain reaction and in situ hybridization.

alpha 2 Adrenergic receptors are involved in mediating pre- and postsynaptic responses in the sympathetic nervous system. In this study, the expression of alpha 2 genes was examined by the amplification of mRNA, extracted from adult rat superior cervical ganglion through reverse transcription and subsequent amplification of appropriate target sequence using polymerase chain reaction and sequence specific oligonucleotide primers for the three alpha 2 receptor genes. Results from these studies have shown that the major alpha 2 adrenergic mRNA transcript was the one that encodes the alpha 2A receptor. Nucleotide sequence of the 312 base-pair (bp) alpha 2A cDNA was homologous to the RG20 adrenergic receptor, the rat homologue of the human alpha 2A receptor. The 312 bp alpha 2A cDNA was used as a probe in Northern blot analysis of the mRNA from superior cervical ganglion and brain. A 3.9 kb mRNA transcript was present in these extracts. To confirm that the alpha 2A gene expression was in the sympathetic neurones we have used the 312 bp alpha 2A cDNA, biotinylated, as a probe for in situ hybridization studies and have demonstrated that the alpha 2A mRNA was found only in the cell bodies of sympathetic neurones.