Disturbed neuronal ER-Golgi sorting of unassembled glycine receptors suggests altered subcellular processing is a cause of human hyperekplexia.

Recent studies on the pathogenic mechanisms of recessive hyperekplexia indicate disturbances in glycine receptor (GlyR) α1 biogenesis. Here, we examine the properties of a range of novel glycine receptor mutants identified in human hyperekplexia patients using expression in transfected cell lines and primary neurons. All of the novel mutants localized in the large extracellular domain of the GlyR α1 have reduced cell surface expression with a high proportion of receptors being retained in the ER, although there is forward trafficking of glycosylated subpopulations into the ER-Golgi intermediate compartment and cis-Golgi compartment. CD spectroscopy revealed that the mutant receptors have proportions of secondary structural elements similar to wild-type receptors. Two mutants in loop B (G160R, T162M) were functional, but none of those in loop D/ß2-3 were. One nonfunctional truncated mutant (R316X) could be rescued by coexpression with the lacking C-terminal domain. We conclude that a proportion of GlyR α1 mutants can be transported to the plasma membrane but do not necessarily form functional ion channels. We suggest that loop D/ß2-3 is an important determinant for GlyR trafficking and functionality, whereas alterations to loop B alter agonist potencies, indicating that residues here are critical elements in ligand binding.

Effects of rehabilitative training and anti-inflammatory treatment on functional recovery and cellular reorganization following stroke.

Post-ischemic inflammation plays a critical role in cellular reorganization and functional recovery after stroke. We therefore address the hypothesis whether anti-inflammatory treatment with either indometacin or minocycline combined with rehabilitative training improve functional recovery and influence perilesional cellular response following focal cortical infarcts. Using the photothrombosis model in adult rats, focal cortical infarcts were induced in the fore- and hindlimb sensorimotor cortex. Inflammatory processes were blocked by intraperitoneal application of indometacin or minocycline twice daily during the first 2 weeks of the experiment. Immediately after the infarct, the animals received a daily session of skilled reaching training of the impaired forelimb. In addition, Bromodeoxyuridine (BrdU) was administrated for 5 sequential days post infarct. Proliferation and differentiation of astrocytes, microglia, immature and mature neurons in the perilesional zone were immunocytochemically quantified at days 14 and 42. Functional recovery was assessed in a sensorimotor walking task preoperatively and 4, 14 and 28 days post surgery. Combined rehabilitative training and indometacin or minocycline strongly improved sensorimotor performance and significantly reduced the number of proliferating microglia compared to reaching training alone. Furthermore, the combination increased the survival of proliferating astrocytes and, moreover, minocycline increased the doublecortin-positive cells in the perilesional zone. Anti-inflammatory drug application combined with rehabilitative training demonstrates improved functional recovery and significantly modifies proliferation and survival of distinct glial and neuronal subpopulations in the direct vicinity of cortical infarcts compared to reaching training alone.