ABSTRACT
Alteration in the expression level of peripheral myelin protein 22 (PMP22) is the most frequent cause for demyelinating neuropathies of Charcot-Marie-Tooth type. Here, we demonstrate a loss of motoneurons (MNs) in the spinal cords from transgenic mice over-expressing Pmp22 (Pmp22(tg)) while mice lacking Pmp22 [Pmp22(ko); knockout (ko)] exhibited normal MN numbers at the symptomatic age of 60 days. In order to describe the molecular changes in affected MNs, these cells were isolated from lumbar spinal cords by laser-capture microdissection. Remarkably, the MNs of the Pmp22(ko) and Pmp22(tg) mice showed different expression profiles because of the altered Pmp22 expression. The changes in the expression profile of MNs from Pmp22(ko) mice resemble those described in MNs from mice after nerve injury and included genes that had been described in neuronal growth and regeneration like Gap43 and Sprr11a. The changes detected in the expression pattern of MNs from Pmp22(tg) mice exhibited fewer similarities to other expression patterns. The specific expression pattern in the MNs of the Pmp22(ko) mice might contribute to the better survival of the MNs. Our study also revealed induction of genes like brain-expressed X-linked 1 (Bex1) and desmoplakin (Dsp) that had recently been found up-regulated in MNs of human amyotrophic lateral sclerosis patients.
Subject(s)
Gene Dosage/physiology , Motor Neurons/pathology , Motor Neurons/physiology , Myelin Proteins/deficiency , Myelin Proteins/genetics , Animals , Cell Survival/genetics , Charcot-Marie-Tooth Disease/genetics , Charcot-Marie-Tooth Disease/metabolism , Charcot-Marie-Tooth Disease/pathology , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Motor Neurons/metabolism , Myelin Proteins/physiology , Nerve Fibers, Myelinated/metabolism , Nerve Fibers, Myelinated/pathology , Nerve Fibers, Myelinated/physiology , Spinal Cord/chemistry , Spinal Cord/metabolism , Spinal Cord/pathologyABSTRACT
This study evaluated the disposition of the two atypical antipsychotics, amisulpride (AMS) and clozapine (CLZ), and its main metabolite N-desmethylclozapine (DCLZ), to their target structures in the central nervous system by applying an in vitro blood-brain barrier and blood-cerebrospinal fluid (CSF) barrier based on monolayers of porcine brain microvessel endothelial cells (PMEC) or porcine choroid plexus epithelial cells (PCEC). Permeation studies through PMEC- and PCEC-monolayers were conducted for 60 min at drug concentrations of 1, 5, 10, and 30 muM applied to the donor compartment. PMEC were almost impermeable for AMS (permeation coefficient, P<1 x 10(-7) cm/s) in the resorptive direction, whereas transport in the secretory direction was observed with a P (+/-SD) of 5.2+/-3.6 x 10(-6) cm/s. The resorptive P of CLZ and DCLZ were 2.3+/-1.2 x 10(-4) and 9.6+/-5.0 x 10(-5) cm/s, respectively. For the permeation across PCEC in the resorptive direction, a P of 1.7+/-2.5 x 10(-6) cm/s was found for AMS and a P of 1.6+/-0.9 x 10(-4) and 2.3+/-1.3 x 10(-5) cm/s was calculated for CLZ and DCLZ, respectively. Both, CLZ and DCLZ, could easily pass both barriers with about a five-fold higher permeation rate of CLZ at the PCEC. The permeation of AMS across the BBB was restricted partly due to an efflux transport. It is thus suggested that AMS reaches its target structures via transport across the blood-CSF barrier.