The pattern of neurodegeneration in Alzheimer's disease (AD) is very distinctive: neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau selectively affect pyramidal neurons of the aging association cortex that interconnect extensively through glutamate synapses on dendritic spines. In contrast, primary sensory cortices have few NFTs, even in late-stage disease. Understanding this selective vulnerability, and why advancing age is such a high risk factor for the degenerative process, may help to reveal disease etiology and provide targets for intervention. Our study has revealed age-related increase in cAMP-dependent protein kinase (PKA) phosphorylation of tau at serine 214 (pS214-tau) in monkey dorsolateral prefrontal association cortex (dlPFC), which specifically targets spine synapses and the Ca 2+ -storing spine apparatus. This increase is mirrored by loss of phosphodiesterase 4A from the spine apparatus, consistent with increase in cAMP-Ca 2+ signaling in aging spines. Phosphorylated tau was not detected in primary visual cortex, similar to the pattern observed in AD. We also report electron microscopic evidence of previously unidentified vesicular trafficking of phosphorylated tau in normal association cortex-in axons in young dlPFC vs. in spines in aged dlPFC-consistent with the transneuronal lesion spread reported in genetic rodent models. pS214-Tau was not observed in normal aged mice, suggesting that it arises with the evolutionary expansion of corticocortical connections in primates, crossing the threshold into NFTs and degeneration in humans. Thus, the cAMP-Ca 2+ signaling mechanisms, needed for flexibly modulating network strength in young association cortex, confer vulnerability to degeneration when dysregulated with advancing age.

As the average lifespan continues to climb because of advances in medical care, there is a greater need to understand the factors that contribute to quality of life in the elderly. The capacity to live independently is highly significant in this regard, but is compromised by cognitive dysfunction. Aging is associated with decreases in cognitive function, including impairments in episodic memory and executive functioning. The prefrontal cortex appears to be particularly vulnerable to the effects of advancing age. Although the mechanism of age-related cognitive decline is not yet known, age-related inflammatory changes are likely to play a role. New insights from preclinical and clinical research may give rise to novel therapeutics which may have efficacy in slowing or preventing cognitive decline with advancing age.

BackgroundChildhood adversity is associated with increased risk for mood, anxiety, impulse control, and substance disorders. Although genetic and environmental factors contribute to the development of such disorders, the neurobiological mechanisms involved are poorly understood. A reliable mouse model of early life adversity leading to lasting behavioral changes would facilitate progress in elucidating the molecular mechanisms underlying these adverse effects. Maternal separation is a commonly used model of early life neglect, but has led to inconsistent results in the mouse.ResultsIn an effort to develop a mouse model of early life neglect with long-lasting behavioral effects in C57BL/6 mice, we designed a new maternal separation paradigm that we call Maternal Separation with Early Weaning (MSEW). We tested the effects of MSEW on C57BL/6 mice as well as the genetically distinct DBA/2 strain and found significant MSEW effects on several behavioral tasks (i.e., the open field, elevated plus maze, and forced swim test) when assessed more than two months following the MSEW procedure. Our findings are consistent with MSEW causing effects within multiple behavioral domains in both strains, and suggest increased anxiety, hyperactivity, and behavioral despair in the MSEW offspring. Analysis of pup weights and metabolic parameters showed no evidence for malnutrition in the MSEW pups. Additionally, strain differences in many of the behavioral tests suggest a role for genetic factors in the response to early life neglect.ConclusionsThese results suggest that MSEW may serve as a useful model to examine the complex behavioral abnormalities often apparent in individuals with histories of early life neglect, and may lead to greater understanding of these later life outcomes and offer insight into novel therapeutic strategies.

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Background Evidence has emerged demonstrating that ethanol influences cytokine expression within the CNS, although most studies have examined long-term exposure. Thus, the cytokine response to an acute ethanol challenge was investigated, in order to characterize profiles of cytokine changes following acute exposure. Methods Rats pups were injected intraperitoneally (i.p.) with 2-g/kg ethanol and IL-1 mRNA and protein assessed 0, 60, 120, 180, and 240 min post-injection (Exp. 1). In Exps. 2-5, the expression of several cytokines was examined in adult male rats during acute intoxication (3 hr after 4-g/kg ethanol), as well as withdrawal (18 hr post-injection), after i.p. and intragastric (i.g.) ethanol administration. Results Early in ontogeny, acute ethanol significantly decreased brain IL-1 mRNA and protein. Subsequently, when adult rats were examined, significant and temporally dynamic alterations in central and peripheral cytokines were observed following acute i.p. ethanol exposure (4-g/kg). Although cytokine- and region-dependent, central IL-6 expression was generally increased and TNFα decreased during intoxication, whereas IL-1 expression exhibited increases during withdrawal. In the periphery, acute i.p. ethanol elevated expression of all cytokines, with the response growing in magnitude as the time post-injection increased. Following acute i.g. ethanol (4-g/kg), intoxication-related increases in IL-6 expression were again observed in the PVN, although to a lesser extent. Long-term, voluntary, intermittent ethanol consumption resulted in tolerance to the effects of an i.g. ethanol challenge (4-g/kg) on PVN IL-6 expression, whereas these same elevations in IL-6 expression were still seen in the amygdala in rats with a history of moderate ethanol intake. Treatment with minocycline did not significantly attenuate i.p. or i.g. ethanol-induced changes in central cytokine expression. Conclusions Together, these studies provide a foundation for understanding fluctuations in central and peripheral cytokines following acute ethanol as potential contributors to the constellation of neural and behavioral alterations observed during ethanol intoxication and withdrawal.