ERK/MAPK Is Essential for Endogenous Neuroprotection in SCN2.2 Cells

Glutamate (Glu) is essential to central nervous system function; however excessive Glu release leads to neurodegenerative disease. Strategies to protect neurons are underdeveloped, in part due to a limited understanding of natural neuroprotective mechanisms, such as those present in the suprachiasmatic nucleus (SCN). This study tests the hypothesis that activation of ERK/MAPK provides essential protection to the SCN after exposure to excessive Glu using the SCN2.2 cells as a model.Immortalized SCN2.2 cells (derived from SCN) and GT1-7 cells (neurons from the neighboring hypothalamus) were treated with 10 mM Glu in the presence or absence of the ERK/MAPK inhibitor PD98059. Cell death was assessed by Live/Dead assay, MTS assay and TUNEL. Caspase 3 activity was also measured. Activation of MAPK family members was determined by immunoblot. Bcl2, neuritin and Bid mRNA (by quantitative-PCR) and protein levels (by immunoblot) were also measured.As expected Glu treatment increased caspase 3 activity and cell death in the GT1-7 cells, but Glu alone did not induce cell death or affect caspase 3 activity in the SCN2.2 cells. However, pretreatment with PD98059 increased caspase 3 activity and resulted in cell death after Glu treatment in SCN2.2 cells. This effect was dependent on NMDA receptor activation. Glu treatment in the SCN2.2 cells resulted in sustained activation of the anti-apoptotic pERK/MAPK, without affecting the pro-apoptotic p-p38/MAPK. In contrast, Glu exposure in GT1-7 cells caused an increase in p-p38/MAPK and a decrease in pERK/MAPK. Bcl2-protein increased in SCN2.2 cells following Glu treatment, but not in GT1-7 cells; bid mRNA and cleaved-Bid protein increased in GT1-7, but not SCN2.2 cells.Facilitation of ERK activation and inhibition of caspase activation promotes resistance to Glu excitotoxicity in SCN2.2 cells.Further research will explore ERK/MAPK as a key molecule in the prevention of neurodegenerative processes

Assessing Sex-Specific Circadian, Metabolic, and Cognitive Phenotypes in the AβPP/PS1 and APPNL-F/NL-F Models of Alzheimer\u27s Disease.

BACKGROUND: Circadian disruption has long been recognized as a symptom of Alzheimer\u27s disease (AD); however, emerging data suggests that circadian dysfunction occurs early on in disease development, potentially preceding any noticeable cognitive deficits. OBJECTIVE: This study compares the onset of AD in male and female wild type (C57BL6/J), transgenic (AβPP/PS1), and knock-in (APPNL-F/NL-F) AD mouse models from the period of plaque initiation (6 months) through 12 months. METHODS: Rhythmic daily activity patterns, glucose sensitivity, cognitive function (Morris water maze, MWM), and AD pathology (plaques formation) were assessed. A comparison was made across sexes. RESULTS: Sex-dependent hyperactivity in AβPP/PS1 mice was observed. In comparison to C57BL/6J animals, 6-month-old male AβPP/PS1 demonstrated nighttime hyperactivity, as did 12-month-old females. Female AβPP/PS1 animals performed significantly worse on a MWM task than AβPP/PS1 males at 12 months and trended toward increased plaque pathology. APPNL-F/NL-F 12-month-old males performed significantly worse on the MWM task compared to 12-month-old females. Significantly greater plaque pathology occurred in AβPP/PS1 animals as compared to APPNL-F/NL-F animals. Female AβPP/PS1 animals performed significantly worse than APPNL-F/NL-F animals in spatial learning and memory tasks, though this was reversed in males. CONCLUSION: Taken together, this study provides novel insights into baseline sex differences, as well as characterizes baseline diurnal activity variations, in the AβPP/PS1 and APPNL-F/NL-F AD mouse models

Riluzole attenuates glutamatergic tone and cognitive decline in AβPP/PS1 mice.

We have previously demonstrated hippocampal hyperglutamatergic signaling occurs prior to plaque accumulation in AβPP/PS1 mice. Here, we evaluate 2-Amino-6-(trifluoromethoxy) benzothiazole (riluzole) as an early intervention strategy for Alzheimer\u27s disease (AD), aimed at restoring glutamate neurotransmission prior to substantial Beta amyloid (Aβ) plaque accumulation and cognitive decline. Male AβPP/PS1 mice, a model of progressive cerebral amyloidosis, were treated with riluzole from 2-6 months of age. Morris water maze, in vivo electrochemistry, and immunofluorescence were performed to assess cognition, glutamatergic neurotransmission, and pathology, respectively, at 12 months. Four months of prodromal riluzole treatment in AβPP/PS1 mice resulted in long-lasting procognitive effects and attenuated glutamatergic tone that was observed six months after discontinuing riluzole treatment. Riluzole-treated AβPP/PS1 mice had significant improvement in long-term memory compared to vehicle-treated AβPP/PS1 mice that was similar to normal aging C57BL/6J control mice. Furthermore, basal glutamate concentration and evoked-glutamate release levels, which were elevated in vehicle-treated AβPP/PS1 mice, were restored to levels observed in age-matched C57BL/6J mice in AβPP/PS1 mice receiving prodromal riluzole treatment. Aβ plaque accumulation was not altered with riluzole treatment. This study supports that interventions targeting the glutamatergic system during the early stages of AD progression have long-term effects on disease outcome, and importantly may prevent cognitive decline. Our observations provide preclinical support for targeting glutamate neurotransmission in patients at risk for developing AD

Physiology of the germinal disc region in preovulatory follicles of the chicken ovary

The germinal disc region (GDR) has been hypothesized to be growth center of the avian preovulatory follicle. This investigation was undertaken to examine critical aspects of the physiology of the GDR with respect to its role in the proliferation and differentiation of the granulosa layer. Specifically, the objectives were: (1) to determine if proliferation and differentiation of granulosa cells overlying the germinal disc was different throughout the final stages of follicular development than granulosa cells located as far from the germinal disc as possible (distal granulosa cells); (2) to examine the effects of LH on proliferation and differentiation of granulosa cells overlying the germinal disc and distal granulosa cells; (3) to determine if plasminogen activator production by the GDR is associated with proliferation; (4) to determine if gradients of proliferation and differentiation are present within an individual preovulatory follicle; and (5) to investigate the production of proliferation-stimulating and steroidogenesis-inhibiting factors by the GDR. The major findings were: (1) granulosa cells overlying the germinal disc proliferate faster and are less differentiated than distal granulosa cells; (2) LH inhibits proliferation of the GDR but has no effect on differentiation of the GDR; (3) GDRs produce high amounts of plasminogen activator through follicular development; (4) plasminogen activator production by the GDR in response to LH depends on the stage of maturation of the follicle; (5) diametrically opposed gradients of proliferation and differentiation present within an individual follicle are established and maintained by the secretion of one or more proliferation-stimulating and steroidogenesis-inhibiting factors by the GDR; and (6) epidermal growth factor, transforming growth factor $\alpha$, transforming growth factor $\beta$ and tumor necrosis factor $\alpha$ are secreted by the GDR. These data clearly illustrate that the GDR regulates follicular growth by secreting specific, paracrine-acting growth factors. The research presented in this thesis emphasize the unique role of the female gamete in follicle selection, development and maturation, culminating in ovulation.U of I OnlyETDs are only available to UIUC Users without author permissio

Role of Aryl Hydrocarbon Receptor in Circadian Clock Disruption and Metabolic Dysfunction

The prevalence of metabolic syndrome, a clustering of three or more risk factors that include abdominal obesity, increased blood pressure, and high levels of glucose, triglycerides, and high-density lipoproteins, has reached dangerous and costly levels worldwide. Increases in morbidity and mortality result from a combination of factors that promote altered glucose metabolism, insulin resistance, and metabolic dysfunction. Although diet and exercise are commonly touted as important determinants in the development of metabolic dysfunction, other environmental factors, including circadian clock disruption and activation of the aryl hydrocarbon receptor (AhR) by dietary or other environmental sources, must also be considered. AhR binds a range of ligands, which prompts protein–protein interactions with other Per-Arnt-Sim (PAS)-domain-containing proteins and subsequent transcriptional activity. This review focuses on the reciprocal crosstalk between the activated AhR and the molecular circadian clock. AhR exhibits a rhythmic expression and time-dependent sensitivity to activation by AhR agonists. Conversely, AhR activation influences the amplitude and phase of expression of circadian clock genes, hormones, and the behavioral responses of the clock system to changes in environmental illumination. Both the clock and AhR status and activation play significant and underappreciated roles in metabolic homeostasis. This review highlights the state of knowledge regarding how AhR may act together with the circadian clock to influence energy metabolism. Understanding the variety of AhR-dependent mechanisms, including its interactions with the circadian timing system that promote metabolic dysfunction, reveals new targets of interest for maintenance of healthy metabolism