Identification of endogenous morphine and a mu3-like opiate alkaloid receptor in human brain tissue taken from a patient with intractable complex partial epilepsy
Gregory Fricchione, Wei Zhu, Patrick Cadet, Kirk J. Mantione, Edward Bromfield, Joseph Madsen, Umberto DeGirolami, Barbara Dworetzky, Bernardino Vaccaro, Peter Black, George B. Stefano
Med Sci Monit 2008; 14(6): CS45-49
We set out to detect whether morphine is present in tissue taken from a patient with intractable temporal lobe epilepsy and to characterize the presence and nature of mu opiate receptor subtypes in this tissue.
Material and Method: In temporal lobe tissue, resected during anteromedial temporal lobectomy for intractable focal epilepsy, morphine was identified by quantitative radioimmunoassay (RIA) coupled to electrochemical detection via high-pressure liquid chromatography (HPLC). In addition, RNA isolated from the medial and lateral temporal lobe specimens was analyzed by conventional and real time reverse transcriptase-polymerase chain reaction (RT-PCR) for the expression of different human receptor gene transcripts. RIA revealed the presence of morphine at 3.4 nanograms per gram of tissue wet weight. Using RT-PCR and a primer specifically set for the mu3 (550 base pair fragment) and mu4 (880 base pair fragment) MOR splice variants, a mu4 splice variant was identified in both brain sections.
Conclusions: This human brain tissue study of a subject with temporal lobe epilepsy documents the presence of endogenous morphine and of a mu4 splice variant. These findings may have implications for our understanding of the mechanism of temporal lobe epilepsy.
Keywords: Polymerase Chain Reaction, Morphine - metabolism, Male, Molecular Sequence Data, Humans, Epilepsy, Complex Partial - metabolism, Electrophoresis, Agar Gel, Receptors, Opioid, mu - metabolism, Brain - metabolism, Base Sequence, Adult