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Abstract
Dysregulation of neuropeptides may play an important role in aging-induced impairments. In the long list of neuropeptides, pituitary adenylate cyclase-activating polypeptide (PACAP) represents a highly effective cytoprotective peptide that provides an endogenous control against a variety of tissue-damaging stimuli. PACAP has neuro- and general cytoprotective effects due to anti-apoptotic, anti-inflammatory, and antioxidant actions. As PACAP is also a part of the endogenous protective machinery, it can be hypothesized that the decreased protective effects in lack of endogenous PACAP would accelerate age-related degeneration and PACAP knockout mice would display age-related degenerative signs earlier. Recent results support this hypothesis showing that PACAP deficiency mimics aspects of age-related pathophysiological changes including increased neuronal vulnerability and systemic degeneration accompanied by increased apoptosis, oxidative stress, and inflammation. Decrease in PACAP expression has been shown in different species from invertebrates to humans. PACAP-deficient mice display numerous pathological alterations mimicking early aging, such as retinal changes, corneal keratinization and blurring, and systemic amyloidosis. In the present review, we summarize these findings and propose that PACAP deficiency could be a good model of premature aging.
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Han P, Nielsen M, Song M, Yin J, Permenter MR, Vogt JA, Engle JR, Dugger BN, Beach TG, Barnes CA, Shi J. The Impact of Aging on Brain Pituitary Adenylate Cyclase Activating Polypeptide, Pathology and Cognition in Mice and Rhesus Macaques. Front Aging Neurosci 2017; 9:180. [PMID: 28659785 PMCID: PMC5467357 DOI: 10.3389/fnagi.2017.00180] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 05/23/2017] [Indexed: 01/30/2023] Open
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is associated with Alzheimer's disease (AD), but its age-related effects are unknown. We chose the rhesus macaque due to its closeness to human anatomy and physiology. We examined four variables: aging, cognitive performance, amyloid plaques and PACAP. Delayed nonmatching-to-sample recognition memory scores declined with age and correlated with PACAP levels in the striatum, parietal and temporal lobes. Because amyloid plaques were the only AD pathology in the old rhesus macaque, we further studied human amyloid precursor protein (hAPP) transgenic mice. Aging was associated with decreased performance in the Morris Water Maze (MWM). In wild type (WT) C57BL/6 mice, the performance was decreased at age 24-26 month whereas in hAPP transgenic mice, it was decreased as early as 9-12 month. Neuritic plaques in adult hAPP mice clustered in hippocampus and adjacent cortical regions, but did not propagate further into the frontal cortex. Cerebral PACAP protein levels were reduced in hAPP mice compared to age-matched WT mice, but the genetic predisposition dominated cognitive decline. Taken together, these data suggest an association among PACAP levels, aging, cognitive function and amyloid load in nonhuman primates, with both similarities and differences from human AD brains. Our results suggest caution in choosing animal models and in extrapolating data to human AD studies.
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Affiliation(s)
- Pengcheng Han
- Department of Neurology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical CenterPhoenix, AZ, United States
- Department of Pathology and Laboratory Medicine Resident Program, Medical University of South CarolinaCharleston, SC, United States
| | - Megan Nielsen
- Department of Neurology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical CenterPhoenix, AZ, United States
| | - Melissa Song
- Department of Neurology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical CenterPhoenix, AZ, United States
| | - Junxiang Yin
- Department of Neurology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical CenterPhoenix, AZ, United States
| | - Michele R. Permenter
- California National Primate Research Center, University of California, DavisDavis, CA, United States
| | - Julie A. Vogt
- California National Primate Research Center, University of California, DavisDavis, CA, United States
| | - James R. Engle
- California National Primate Research Center, University of California, DavisDavis, CA, United States
- Evely F. McKnight Brain Institute, University of ArizonaTucson, AZ, United States
| | - Brittany N. Dugger
- Institute for Neurodegenerative Diseases, University of California, San FranciscoSan Francisco, CA, United States
- Civin Laboratory for Neuropathology, Banner Sun Health Research InstituteSun City, AZ, United States
| | - Thomas G. Beach
- Civin Laboratory for Neuropathology, Banner Sun Health Research InstituteSun City, AZ, United States
| | - Carol A. Barnes
- California National Primate Research Center, University of California, DavisDavis, CA, United States
- Evely F. McKnight Brain Institute, University of ArizonaTucson, AZ, United States
- Division of Neural Systems, Memory and Aging, University of ArizonaTucson, AZ, United States
- Departments of Psychology, Neurology, and Neuroscience, University of ArizonaTucson, AZ, United States
| | - Jiong Shi
- Department of Neurology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical CenterPhoenix, AZ, United States
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General HospitalTianjin, China
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Pirger Z, Naskar S, László Z, Kemenes G, Reglődi D, Kemenes I. Reversal of age-related learning deficiency by the vertebrate PACAP and IGF-1 in a novel invertebrate model of aging: the pond snail (Lymnaea stagnalis). J Gerontol A Biol Sci Med Sci 2014; 69:1331-8. [PMID: 24846768 PMCID: PMC4197904 DOI: 10.1093/gerona/glu068] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
With the increase of life span, nonpathological age-related memory decline is affecting an increasing number of people. However, there is evidence that age-associated memory impairment only suspends, rather than irreversibly extinguishes, the intrinsic capacity of the aging nervous system for plasticity (1). Here, using a molluscan model system, we show that the age-related decline in memory performance can be reversed by administration of the pituitary adenylate cyclase activating polypeptide (PACAP). Our earlier findings showed that a homolog of the vertebrate PACAP38 and its receptors exist in the pond snail (Lymnaea stagnalis) brain (2), and it is both necessary and instructive for memory formation after reward conditioning in young animals (3). Here we show that exogenous PACAP38 boosts memory formation in aged Lymnaea, where endogenous PACAP38 levels are low in the brain. Treatment with insulin-like growth factor-1, which in vertebrates was shown to transactivate PACAP type I (PAC1) receptors (4) also boosts memory formation in aged pond snails. Due to the evolutionarily conserved nature of these polypeptides and their established role in memory and synaptic plasticity, there is a very high probability that they could also act as “memory rejuvenating” agents in humans.
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Affiliation(s)
- Zsolt Pirger
- Balaton Limnological Institute, Centre for Ecological Research, Hungarian Academy of Sciences, Tihany, Hungary. Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton. Department of Anatomy MTA-PTE, "Momentum" PACAP Team, University of Pécs, Hungary
| | - Souvik Naskar
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton
| | - Zita László
- Balaton Limnological Institute, Centre for Ecological Research, Hungarian Academy of Sciences, Tihany, Hungary. Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton
| | - György Kemenes
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton
| | - Dóra Reglődi
- Department of Anatomy MTA-PTE, "Momentum" PACAP Team, University of Pécs, Hungary
| | - Ildikó Kemenes
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton.
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