Journal of neural transplantation最新文献

In the mouse whiskerpad there is a group of vibrissal follicles arranged in five rows, which are topologically represented in the contralateral somatosensory cortex by the barrelfield. Each vibrissal follicle is a specialized sensory organ containing a large number of receptors, mostly Merkel cells. In these experiments, the parts of the vibrissal follicles containing most of the receptors were transplanted to different regions of the whiskerpad of newborn mice, to know whether "new", supranumerary barrels could develop. The results confirm this hypothesis. However, the "new" barrels are not topologically represented in the barrelfield, as normal barrels do.

We have utilized the carbocyanine dye, DiI, to label suspensions of dissociated ciliary ganglion cells removed from 6 to 12 day old quail embryos. Some of the cells were injected into the trunk somites of 2.5-3 day old chick embryos along pathways where neural crest cells migrate to form sensory and sympathetic ganglia, aortic plexuses and the adrenal medulla; the remainder of the cells were cultured to check their viability and the persistence of the DiI label. Embryos were incubated for 1-8 days post-injection, fixed in 4% paraformaldehyde/0.25% glutaraldehyde and processed for cryostat sectioning. DiI-labelled cells were readily identifiable in culture and in sections of embryos at all stages examined. Several cell types were identified, based on their morphology and soma size. These included cells with large cell bodies and bright DiI-labelling that appeared to be neurons and smaller, more weakly labelled cells that appeared non-neuronal. The latter presumably had divided several times, accounting for their reduced levels of dye. Many of the DiI-labelled cells were found in and around neural crest-derived sympathetic ganglia, aortic plexuses and adrenomedullary cords, but were rarely observed in dorsal root ganglia. The aldehyde fixative (Faglu mixture) used in this study reacts with catecholamines to form a bright reaction product in adrenergic cells including those in the sympathetic ganglia and the adrenal medulla. The catecholamine biproduct and the DiI in the same cell can easily be viewed with different fluorescent filter sets. A variable number of the DiI-labelled cells in these adrenergic sites contained catecholamines. Cells derived from younger 6 day ciliary ganglion dissociates exhibited detectable catecholamine neurotransmitters earlier and more frequently than those derived from 8 day embryos. The presence of cells exhibiting both bright DiI and catecholamine fluorescence is consistent with previous indications that post-mitotic ciliary ganglion neurons can undergo phenotypic conversion from cholinergic to adrenergic when transplanted to the trunk environment.

The effects of donor age and site of placement on the survival of fetal medial habenula (MH) transplants into adult rats hosts were examined. The innervation of the interpeduncular nucleus (IPN) in such cases was also examined. Explants of MH consisting of the medial-dorsal lip of the third ventricle were held in vitro for 1-2 days. Colloidal gold conjugated to wheat germ agglutinin was added for the last 18 hours to label the cells. Four of 16 cases with E19 derived transplants contained donor neurons. Markedly larger transplants were present in 95% of 20 cases with E16 derived transplants. Sites in the ventral midbrain were successful, while limited or no survival occurred at sites more remote from IPN. Retrograde labeling of transplant neurons was present in each case studied with HRP injection into host IPN. Colloidal gold-labeled macrophages, some oriented capillaries and GFAP-positive processes marked the donor-host interface. In EM the interface was evident only by the difference in tissue elements in the transplant versus host. Numerous synapses of Gray types I and II were present in the transplant. Excellent survival of MH neurons, donor/host interfaces, innervation of IPN by the transplant and fine structure in and around the transplants, all suggest that such preparations are suitable for further experimental analysis of the habenulo-interpeduncular system.

We have previously shown that sera from patients with Alzheimer's disease (AD) contain a significantly high level of antibodies to the cell bodies (Perikarya; PK) but not to the nerve terminals (synaptosomes) of purely cholinergic neurons from the electric fish Torpedo. In the present study we examined the effect of repeated immunization of rats with either of these antigens for one year. Immunoblot studies revealed that sera of cholinergic PK immunized rats contained a high level of antibodies to cholinergic PK proteins, in particular to a 200 kilodalton protein, to which there are specifically high levels of antibodies in AD. Sera from rats immunized with cholinergic synaptosomes and from control rats contained very low levels of these antibodies. Behavioral studies performed one year after the initial immunization revealed that the cholinergic PK immunized rats were impaired in spatial learning and memory tasks (Morris swim test and T-maze alternation) when compared to control rats and that the synaptosome-immunized rats showed no such deficit. In contrast, the three groups performed similarly in general activity, active avoidance and conditioned emotional response tests. Further experiments revealed that the cholinergic PK immunized rats displayed a significant deficit in short term memory. The association of antibodies to cholinergic neurons with cognitive deficits in this rat model suggests that such antibodies may be involved in the pathogenesis of AD.