Neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS), Alzheimer’s disease, and Parkinson’s disease, are characterized by the progressive loss of neurons in specific regions of the brain and/or spinal cord. Neuronal cell loss typically occurs by either apoptotic or necrotic mechanisms. Oxidative stress and nitrosative stress, along with excitotoxicity and caspase activation, have all been implicated as major underlying causes of neuronal cell death. Diverse nutraceuticals (bioactive compounds found in common foods) have been shown to have neuroprotective effects in a variety of in vitro and in vivo disease models. In the current study, we compared the neuroprotective effects of two polyphenolic compounds, rosmarinic acid and carnosic acid, which are both found at substantial concentrations in the herb rosemary. The capacity of these compounds to rescue primary cultures of rat cerebellar granule neurons (CGNs) from a variety of stressors was investigated. Both polyphenols significantly reduced CGN death induced by the nitric oxide donor, sodium nitroprusside (nitrosative stress). Rosmarinic acid uniquely protected CGNs from glutamate-induced excitotoxicity, while only carnosic acid rescued CGNs from caspase-dependent apoptosis induced by removal of depolarizing extracellular potassium (5K apoptotic condition). Finally, we found that carnosic acid protects CGNs from 5K-induced apoptosis by activating a phosphatidylinositol 3-kinase (PI3K) pro-survival pathway. The shared and unique neuroprotective effects of these two compounds against diverse modes of neuronal cell death suggest that future preclinical studies should explore the potential complementary effects of these rosemary polyphenols on neurodegenerative disease progression.

Traumatic brain injury (TBI) is a major public health problem estimated to affect nearly 1.7 million people in the United States annually. Due to the often debilitating effects of TBI, novel preventative agents are highly desirable for at risk populations. Here, we tested a whey protein supplement, Immunocal®, for its potential to enhance resilience to TBI. Immunocal® is a non-denatured whey protein preparation which has been shown to act as a cysteine delivery system to increase levels of the essential antioxidant glutathione (GSH). Twice daily oral supplementation of CD1 mice with Immunocal for 28 days prior to receiving a moderate TBI prevented an ~ 25% reduction in brain GSH/GSSG observed in untreated TBI mice. Immunocal® had no significant effect on the primary mechanical injury induced by TBI, as assessed by MRI, changes in Tau phosphorylation, and righting reflex time or apnea. However, pre-injury supplementation with Immunocal® resulted in statistically significant improvements in motor function (beam walk and rotarod) and cognitive function (Barnes maze). We also observed a significant preservation of corpus callosum width (axonal myelination), a significant decrease in degenerating neurons, a reduction in Iba1 (microglial marker), decreased lipid peroxidation, and preservation of brain-derived neurotrophic factor (BDNF) in the brains of Immunocal®-pretreated mice compared to untreated TBI mice. Taken together, these data indicate that pre-injury supplementation with Immunocal® significantly enhances the resilience to TBI induced by a moderate closed head injury in mice. We conclude that Immunocal® may hold significant promise as a preventative agent for TBI, particularly in certain high risk populations such as athletes and military personnel.

Alzheimer's disease is characterized by progressive memory loss, death of hippocampal, cortical pyramidal and basal forebrain cholinergic neurons, and formation of amyloid-beta (Aβ) plaques and neurofibrillary tangles. Neurotoxic fragments of amyloid-beta protein precursor (AβPP), such as Aβ1-42, are generated by amyloidogenic processing via β-and γ-secretases. However, recent findings suggest that full length AβPP is also toxic to neurons, although the mechanism by which the non-cleaved protein induces cell death is presently unclear. Here, we utilize a transient transfection strategy to show that overexpression of wild type (WT) AβPP in mouse hippocampal HT22 cells induces caspase-dependent apoptosis. Cell death induced by AβPP is independent of the mitochondrial permeability transition but requires the activation of Bax. Incubation with β-or γ-secretase inhibitors has no effect on AβPP content or apoptosis and the mechanism of AβPP-induced cell death in HT22 cells is distinct from that of Aβ1-42 overexpression. Importantly, a mutant of AβPP that does not localize to mitochondria fails to induce apoptosis in HT22 cells. Finally, ρ0 SH-SY5Y neuroblastoma cells lacking functional mitochondria are resistant to AβPP-induced apoptosis. These findings demonstrate that the localization of full length AβPP to functional mitochondria is a prerequisite for this molecule to induce Bax-dependent apoptosis of hippocampal neuronal cells.