NT-3 Levels Research Articles

1407 Age-related changes in levels of NGF, BDNF and NT-3 in the mouse brain

Inter-strain differences in bone mass and density during growth were followed in three strains of mice: SAM-P/2, SAM-R/1 and SAM-P/6 (a murine model of senile osteoporosis, Matsushita et al., Am J Pathol 1986;125:276–283). Photometrically, the inter-strain disparities first appeared in mice at about age 28 days and increased until age 60 days. During this period, tetracycline labelling revealed significant strain differences regarding rate of the appositional formation at the endosteal surface but not at the periosteal surface. The order coincided with sesults of the photometrical assay, that is, highest in SAM-P/2, followed by SAM-R/1 and SAM-P/6, respectively. Therefore, strain differences, especially the osteopenic state of SAM-P/6, occur, at least in part, by disparities in endosteal formation rates during cortical bone modelling.

Expression of mRNAs for neurotrophins and their receptors in the rat choroid plexus and dura mater.

The presence of the neurotrophin, nerve growth factor, brain derived neurotrophic factor, neurotrophin-3 and neurotrophin-4 (NGF, BDNF, NT-3 and NT-4) and their receptors of the tyrosine kinase family (trkA, trkB and trkC) have been investigated in the choroid plexus and dura mater of the adult rat by ribonuclease protection assay. The choroid plexus contained high levels of mRNAs for NGF and NT-4, and low levels of NT-3 and BDNF mRNA; and high levels of trkB mRNA, and undetectable levels of trkA and trkC mRNA. In the dura mater there were high levels of NT-3 and NGF, and low levels of BDNF and NT-4 mRNAs; and high levels of trkC mRNA, and relatively high amount of trkB mRNA, while levels of trkA mRNA was undetectable. The present analysis revealed a different distribution of neurotrophins and their related receptors in the choroid plexus and dura mater.

The levels of neurotrophin-3 protein in the rat brain determined by enzyme immunoassay show a pattern distinct from nerve growth factor

Using the monoclonal antibody 3W3 a two-site enzyme immunoassay (EIA) for neurotrophin-3 (NT 3) was established. The assay was sensitive to levels of NT-3 below 10 pg/ml and does not recognize nerve growth factor (NGF) or brain-derived neurotrophic factor (BDNF). In the adult rat brain, highest levels of NT-3 (1-1.5 ng/g tissue) were found in hippocampus and piriform cortex. Also the cerebellum contained detectable NT-3 protein. In the postnatal (P1 and P5) rat brain very high levels of NT-3 (7–9 ng/g) were found in the cingulate cortex consistent with previous observations of a local, transient NT-3 mRNA expression. NT-3 was also found prenatally in hippocampus, telencephalon and cerebellum. The EIA shows that the pattern of NT-3 protein in brain tissues is distinct from that of NGF.

Neurotrophin-3 prevents the death of adult central noradrenergic neurons in vivo.

Neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4), together with nerve growth factor and brain-derived neurotrophic factor, are members of the neurotrophin family of proteins, which supports the survival of vertebrate neurons. However, no function in vivo has been described for NT-4 and limited information is available on the role of the other neurotrophins in the central nervous system in vivo. Nerve growth factor prevents the degeneration of lesioned septal cholinergic neurons in the adult brain, whereas brain-derived neurotrophic factor prevents the death of developing motor neurons and a subpopulation of adult septal cholinergic neurons. Finally, NT-3 partially prevents the death of facial motor neurons in newborn rats. To assess the role of NT-3 and NT-4 in the adult brain in vivo, we implanted genetically modified fibroblasts that constitutively express high levels of NT-3 or NT-4. The results show that NT-3, but no other neurotrophin, prevents the degeneration of noradrenergic neurons of the locus coeruleus in a 6-hydroxydopamine lesion model that resembles the pattern of cell loss found in Alzheimer's disease. These results imply that NT-3 may have therapeutic potential for preventing the death of noradrenergic neurons in the locus coeruleus.