Assessment of excitability at the brainstem and cortex in primary headaches with allodynia.

PURPOSE: The aims were to assess the excitability of motor cortex and trigeminal structures in patients with primary headaches experiencing allodynia and to investigate the alterations in interictal allodynia and blink reflex excitability after repetitive transcranial magnetic stimulation (rTMS). METHODS: Patients with strictly lateralized primary headaches were included, and Allodynia Symptom Checklist was used to detect allodynia. Paired transcranial magnetic stimulation and blink reflex recovery studies were performed on both sides. Ten Hertz or sham rTMS was applied on the motor cortex in patients with interictal allodynia. Allodynic symptoms were registered quantitatively, and blink reflex study was repeated after these trials. RESULTS: Seventeen of 34 patients with headache described allodynia. Our findings showed bilateral hyperexcitability of cortical and trigeminal structures in the allodynic group. Interictal allodynia, detected in 13 allodynic patients, improved after rTMS as compared with sham stimulation, and this effect appeared to be more evident in the late period. CONCLUSIONS: Bilateral increases in the cortical and trigeminal excitability were shown in patients with allodynia, and rTMS was effective for reducing clinical allodynia. The authors suggest that allodynic condition of the patients should be taken into account in the planning and evaluation of electrophysiological studies, and rTMS may be considered as a treatment alternative for troublesome allodynia.

Detection of the human GPR50 orphan seven transmembrane protein by polyclonal antibodies mapping different epitopes.

GPR50 is an orphan seven transmembrane protein related to the melatonin receptor subfamily comprising MT(1) and MT(2) receptors. In the absence of any known ligand for GPR50, other tools are critical for the characterization of this protein. Here, we describe the generation, purification and characterization of the first rabbit polyclonal antibodies generated against peptides corresponding to the N-terminus, C-terminus and two additional regions within the intracellular tail of GPR50. Immune sera were purified on peptide-antigen affinity columns. Antibodies specifically recognized a GPR50-YFP fusion protein on the plasma membrane of HEK 293 cells in immunofluorescence experiments. In Western blot experiments, the monomeric and dimeric forms of GPR50 were detected as proteins of 66 and 130 kDa, respectively. In addition, these new antibodies were sufficiently sensitive to detect GPR50 in brain slices of the rat pituitary and human hippocampus. In conclusion, we successfully produced antibodies against the orphan GPR50 protein that will become valuable tools for functional studies of this protein.