BACKGROUND AND PURPOSE - Humanin (HN) is a 24-amino acid peptide best known for its ability to protect neurons from damage caused by Alzheimer disease-related proteins. This study examines the neuroprotective effects of HNG (a potent form of HN) on focal cerebral ischemia/reperfusion injury in mice. METHODS - Mice underwent middle cerebral artery occlusion for 75 minutes followed by 24-hour reperfusion. Mice were pretreated with 0.1 μg HNG (intracerebroventricularly) 30 minutes before ischemia; posttreated at 0, 2, 4, and 6 hours after ischemia; or pretreated with 1 μg HNG (intraperitoneally) 1 hour before ischemia. Neurological deficits and cerebral infarct volume were evaluated. Neuronal apoptosis and activated poly(ADP-ribose) polymerase expression were measured by TUNEL and Western blot analysis, respectively. Activated ERKs were examined by Western blot analysis. RESULTS - Pretreatment with 0.1 μg HNG (intracerebroventricularly) 30 minutes before ischemia reduced cerebral infarct volume from 56.2±3.0% to 26.1±1.4% (P<0.01). HNG posttreatment after 4 hours of reperfusion reduced cerebral infarct volume to 45.6±2.6% (P<0.05). Pretreatment with 1 μg HNG (intraperitoneally) 1 hour before ischemia or posttreatment after 2 hours of reperfusion reduced cerebral infarct volume significantly. HNG also significantly improved neurological function and inhibited both neuronal apoptosis as well as poly(ADP-ribose) polymerase activation. A significant decrease of phospho-ERK was observed in mice treated with HNG, whereas phospho-JNK and phospho-p38 levels were not altered. CONCLUSIONS - Our results demonstrate that HNG protects against cerebral ischemia/reperfusion injury in mice. HNG offers neuroprotection in vivo at least in part by inhibiting ERK activation. These findings suggest a potential therapeutic role for HNG in the treatment of stroke.

It is now well accepted that there is a close relationship between noradrenergic and dopaminergic neurons in the brain, especially referring to the modulation of the locus coeruleus–norepinephrine (LC-NE) system on dopamine transmission. The disturbance of this modulation may contribute to neurodegeneration of dopaminergic neurons in Parkinson’s disease. In this article, we briefly review evidence related to such modulation. Firstly, we illustrated the noradrenergic innervation and functional implication for the LC-NE system and nigra–striatum dopaminergic system. Furthermore, we depicted neuroprotective effects of the LC-NE on dopaminergic neurons in vivo and in vitro. Moreover, we present data implicating the potential mechanisms underlying the modulation of the LC-NE system on dopaminergic neurons, in particular the effects of NE as a neurotrophic factor and through its ability to stimulate the expression of other neurotrophic factors, such as the brain-derived neurotrophic factor. Finally, we discussed other mechanisms intrinsic to NE’s effects. A better understanding of the noradrenergic modulation on dopaminergic neurons may be rewarding by significant advances in etiologic study and promising treatment of Parkinson’s disease.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Parkinson's disease (PD), the second most common neurodegenerative disorder after Alzheimer's disease, is one of the leading disability disorders with about 10 million people affected worldwide. The pathological hallmarks of PD are defined by the loss of dopaminergic neurons in the substantia nigra pars compacta of the midbrain with its characteristic clinical motor and non-motor symptoms. However, the loss in dopaminergic neurons causes characteristic clinical manifestations, which include non-motor and motor symptoms. Damage to cholinergic neurotransmitter systems causes non-motor symptoms like sleeping disorders, depression, and a variety of other psychiatric issues, while a malfunctioning nigrostriatal dopaminergic pathway causes such motor symptoms as tremors, stiffness, and postural instability. PD symptoms usually mirror the degree of alteration to neuronal integrity in the affected parts of the brain, but the severity of progression varies with each patient.

Indiana University-Purdue University Indianapolis (IUPUI) / The adaptive arm of the immune system is necessary for facial motoneuron (FMN) survival after facial nerve axotomy (FNA). CD4+ T cells mediate FMN survival after FNA in an interleukin-10 (IL-10) dependent manner, but are not themselves the cellular source of neuroprotective IL-10. The aims of this study are to elucidate the neuroprotective capacity of cell-specific IL-10 expression, and to investigate the manner in which CD4+ T cells participate in IL-10 signaling after FNA. Immunohistochemistry revealed that FMN themselves were constitutive producers of IL-10, and astrocytes were induced to make IL-10 after FNA. Il10 mRNA co-localized with microglia before and after axotomy, but microglial production of IL-10 protein was not detected. To determine whether any single source of IL-10 is critical for FMN survival, Cre/Lox mouse strains were utilized to selectively knock out IL-10 in neurons, astrocytes, and microglia. In agreement with the localization data reflecting concerted IL-10 production by multiple cell types, no single cellular source of IL-10 was necessary for FMN survival. Gene expression analysis of wild-type, immunodeficient, and immune cell-reconstituted animals was performed to determine the role of the immune system in modulating the central IL-10 signaling cascade. This revealed that CD4+ T cells were necessary for full upregulation of central IL-10 receptor (IL-10R) expression after FNA, regardless of their own IL-10R beta (IL-10RB) expression or IL-10R signaling capability. Surprisingly, the ability of CD4+ T cells to respond to IL-10 was critical for their ability to mediate neuroprotection. Adoptive transfer of IL-10RB-deficient T cells resulted in increased central expression of genes associated with microglial activation, antigen presentation, T cell co-stimulation, and complement deposition in response to injury. These data suggest that IL-10RB functions on the T cell to prevent non-neuroprotective immune activation after axotomy. The conclusions drawn from this study support a revised hypothesis for the mechanisms of IL-10-mediated neuroprotection, in which IL-10 serves both trophic and immune-modulating roles after axotomy. This research has implications for the development of immune-modifying therapies for peripheral nerve injury and motoneuron diseases. / 2 years (2021-05-24)

Indiana University-Purdue University Indianapolis (IUPUI) / The vascular network highly coordinates with the central nervous system (CNS) on exchanging oxygen, nutrients and information transfer. The resemblance of the two systems at anatomical, cellular, and molecular levels also demonstrates their interdependence. The spinal cord is an integrated part of the CNS. Traumatic spinal cord injury (SCI) causes rapid systemic vascular responses and local neural tissue damage at the initial phase. The early disruption of the spinal vasculature breaks the supply-and-demand balance and facilitates the deterioration of the spinal cord tissue and functional deficits. Therefore, it is important to dissect the mechanism underlying vascular injury-mediated histological and functional consequences in order to develop potential therapeutic strategies. To visualize dynamic vascular changes after an acute SCI, a novel duo-color in vivo imaging technique was successfully developed in adult rats at the cervical level. This technique overcomes previous technical hurdles allowing real-time observation of vascular changes in live animals. Correlated with histological measures, in vivo vascular outcomes revealed a temporospatial relationship with neuronal and axonal loss, myelin disruption, inflammation, and glial responses. For the first time, we defined a “transitional zone” where significant blood vessel dilation and vascular leakage were observed simultaneously with vascular changes occurred at the injury epicenter acutely after SCI. These vascular changes at the transitional zone happened before any other cellular damage after SCI, suggesting a time window to prevent further neuronal damage in this region. Targeting the observed vascular leakage can work as a proof of concept that early vascular dysfunction contributes to the secondary neural tissue damage. Indeed, intravenous delivery of ferulic acid conjugated with glycol chitosan (FA-GC) to the injured sites immediate after SCI resulted in reduced vascular leakage, ventral horn neuronal loss, and partial recovery of forelimb function following a clinically-relevant contusive SCI at the 7th cervical spinal cord level. In conclusion, this work elucidated a novel role and mechanism of early vascular damage in the “transitional zone” prior to the secondary damage of neural tissue in this region and provided a novel treatment strategy for early neuroprotection and functional recovery. / 2021-11-04

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<p> Schizophrenia is treated with haloperidol, an antipsychotic drug. Although highly effective in treating the positive symptoms of this disease, extrapyramidal side effects also accompany haloperidol treatment, including parkinsonism. Previous investigations revealed that dopamine receptor blockade by haloperidol was not temporally correlated with the appearance of parkinsonian side effects, which begin approximately 3 weeks after haloperidol treatment. In fact, by using tyrosine hydroxylase as a marker for dopamine, TH-immunoreactivity was significantly decreased 5 minutes after haloperidol administration and further downregulation was seen after 10 minutes. Microglial activation has also been implicated in Parkinson's disease models. Haloperidol also induces maximal microglial activation at 5 minutes after administration, with activation increasing by 2 minutes. In this respect, microglial activation may precede TH downregulation, thereby mediating the downregulation. In order to test this possibility, minocycline, a microglial inhibitor, was administered to Sprague-Dawley rats. Minocycline successfully inhibited microglial activation and showed partial protection over TH levels. Caffeine and nicotine have also been implicated as neuroprotective agents in Parkinson's disease. Epidemiological evidence has indicated that both caffeine and nicotine protect against Parkinson's disease. Therefore, caffeine and nicotine were independently tested and found to both prevent TH downregulation and inhibit microglial activation. Overall, microglial activation has been found to correlate with TH downregulation induced by haloperidol. Minocycline, nicotine and caffeine have all been found to inhibit microglial activation, preventing neurotoxicity associated with haloperidol administration. </p> / Thesis / Master of Science (MSc)