| Abstract: |
Our previous studies revealed at least sixteen variants in the mouse Oprm gene with four additional new variants reported in this meeting. One of the variants, mMOR-1B4, contained the same exons 1, 2 and 3 as the original MOR-1, but with a different fourth exon resulting from alternative splicing of exon 5, which predicted a unique 39 amino acid sequence. mMOR-1B4 displays interesting opioid binding profiles when expressed in CHO cells. It bound mu antagonists like CTAP and CTOP, diprenorphine and naloxone quite potently. However, it has very low affinities toward mu agonists such as DAMGO and morphine. The present study examined mMOR-1B4-like immunoreactivity in the mouse central nervous system using a rabbit antisera generated against a unique predicted peptide sequence of mMOR-1B4. In addition, the regional distribution of mMOR-1B4-like immunoreactivity in the mouse central nervous system was mapped and compared with those of the original MOR-1 and mMOR-1C. These studies provide insight to the functional significance of mMOR-1B4 and the mechanisms responsible for the specific processing of the Oprm gene in the central nervous system. |
