Tamoxifen and Src kinase inhibitors as neuroprotective/neuroregenerative drugs after spinal cord injury

Spinal cord injury(SCI) is a devastating condition that produces significant changes in the lifestyle of patients. Many molecular and cellular events are triggered after the initial physical impact to the cord. Two major phases have been described in the field of SCI: an acute phase and late phase. Most of the therapeutic strategies are focused on the late phase because this provides an opportunity to target cellular events like apoptosis, demyelination, scar formation and axonal outgrowth. In this mini-review, we will focus on two agents(tamoxifen and a Src kinase family inhibitor known as PP2) that have been shown in our laboratory to produce neuroprotective(increase cell survival) and/or regenerative(axonal outgrowth) actions. The animal model used in our laboratory is adult female rat(~250 g) with a moderate contusion(12.5 mm) to the spinal cord at the T10 level, using the MASCIS impactor device. Tamoxifen or PP2 was administered by implantation of a 15 mg pellet(Innovative Research of America, Sarasota, FL, USA) or by intraperitoneal injections(1.5 mg/kg, every 3 days), respectively, to produce a long-term effect(28 days). Tamoxifen and the Src kinase inhibitor, PP2, are drugs that in rats with a moderate spinal cord injury promote functional locomotor recovery, increase spared white matter tissue, and stimulate axonal outgrowth. Moreover, tamoxifen reduces the formation of reactive oxygen species. Therefore, these drugs are possible therapeutic agents that have a neuroprotective/regenerative activity in vertebrates with SCI.     

Modified Western blot assay for confirmation and differentiation of human T cell lymphotropic virus types I and II

Disease association studies of human T cell lymphotropic virus (HTLV) types I and II are hindered by the need for multiple assays to confirm and differentiate between the viruses. A modified Western blot assay has been developed using HTLV-I viral lysate and unique (MTA-4) and shared (p21E) HTLV recombinant proteins. By defining confirmation of infection as the presence of antibodies to p24 gag protein and to p21E, all 56 HTLV-I and 49 HTLV-II antisera were confirmed by this modified Western blot alone. Differentiation was determined by reactivity to MTA-4. All HTLV-I antisera reacted with MTA-4 and all HTLV-II antisera did not react with MTA-4. These findings indicate the utility of selected HTLV-I recombinant proteins in a single assay format to confirm and differentiate infections with HTLV-I and HTLV-II.     

Exposure of Rats to Ethanol from Postnatal Days 4 to 8: Alterations of Cholinergic Neurochemistry in the Hippocampus and Cerebellum at Day 20

Brief neonatal ethanol exposure (3.0 g/kg/dose, twice daily; postnatal day (PN) 4 to PN8) resulted in cholinergic neurochemical alterations in the cerebellum, but not the hippocampus of rats assayed on PN20. Analysis revealed that the binding affinity of cerebellar muscarinic receptors for [3H]quinuclidinyl benzilate was decreased by ethanol, but only in female pups. Other gender-specific but treatment-independent cerebellar differences were identified as well, including lower levels of choline acetyltransferase activity and S1-level (1,000 x g) crude protein in males and females, respectively. No evidence of ethanol-induced cholinergic change was noted in the hippocampus of the same pups on PN20. However, collapsed across treatment, male hippocampi were found to contain less S1-level protein than their female counterparts. Neither muscarinic receptor density nor acetyl cholinesterase activity were found to differ between treatments or genders, in either brain region. Consistent with the developmental timetables for regional cholinergic synaptogenesis in the rat, observations on PN20 confirm a hypothesis of cerebellar cholinergic vulnerability and hippocampal cholinergic resilience to neonatal ethanol insult.