Alzheimer Disease: Perez SE

Mufson EJ, Counts SE, Perez SE, Ginsberg SD. · Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612, USA. · Expert Rev Neurother. · Pubmed #18986241 No free full text.

Abstract: Alzheimer's disease (AD) is characterized by a progressive phenotypic downregulation of markers within cholinergic basal forebrain (CBF) neurons, frank CBF cell loss and reduced cortical choline acetyltransferase activity associated with cognitive decline. Delaying CBF neurodegeneration or minimizing its consequences is the mechanism of action for most currently available drug treatments for cognitive dysfunction in AD. Growing evidence suggests that imbalances in the expression of NGF, its precursor proNGF and the high (TrkA) and low (p75(NTR)) affinity NGF receptors are crucial factors underlying CBF dysfunction in AD. Drugs that maintain a homeostatic balance between TrkA and p75(NTR) may slow the onset of AD. A NGF gene therapy trial reduced cognitive decline and stimulated cholinergic fiber growth in humans with mild AD. Drugs treating the multiple pathologies and clinical symptoms in AD (e.g., M1 cholinoceptor and/or galaninergic drugs) should be considered for a more comprehensive treatment approach for cholinergic dysfunction.

Counts SE, Perez SE, Mufson EJ. · Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street Suite 300, Chicago, Ilinois 60612, USA. · Cell Mol Life Sci. · Pubmed #18500641 No free full text.

Abstract: Galanin (GAL) and GAL receptors (GALRs) are overexpressed in degenerating brain regions associated with cognitive decline in Alzheimer's disease (AD). The functional consequences of GAL plasticity in AD are unclear. GAL inhibits cholinergic transmission in the hippocampus and impairs spatial memory in rodent models, suggesting GAL overexpression exacerbates cognitive impairment in AD. By contrast, gene expression profiling of individual cholinergic basal forebrain (CBF) neurons aspirated from AD tissue revealed that GAL hyperinnervation positively regulates mRNAs that promote CBF neuronal function and survival. GAL also exerts neuroprotective effects in rodent models of neurotoxicity. These data support the growing concept that GAL overexpression preserves CBF neuron function which in turn may slow the onset of AD symptoms. Further elucidation of GAL activity in selectively vulnerable brain regions will help gauge the therapeutic potential of GALR ligands for the treatment of AD.

Mufson EJ, Counts SE, Perez SE, Binder L. · Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street, Suite 300, Chicago, IL 60612, USA. · Neuropeptides. · Pubmed #15893372 No free full text.

Abstract: Galanin (GAL) is a biologically active 29 amino acid (30 in humans) which participates in the modulation of several ascending neurotransmitter systems including cholinergic basal forebrain (CBF) neurons, which undergo extensive degeneration in Alzheimer's disease (AD). GAL immunoreactive fibers within the CBF display hypertrophy and hyperinnervate surviving CBF neurons in late AD. Over the years, this unique neuronal plasticity response has been an active area of research for our group. We have examined tissue from a clinically well characterized cohort of retired elderly clergy to determine whether people with mild cognitive impairment display GAL hyperinnervation upon CBF neurons. We found that GAL hyperinnervation is a late stage event and that CBF neuron reduction is not correlated with GAL over expression during prodromal AD. Interestingly, findings from our laboratory using tau immunohistochemistry and single cell gene array technologies suggest that GAL remodeling may influence neurofibrillary tangle formation by altering tau phosphorylation events in CBF neurons in AD. Studies using GAL-tg mice suggest that GAL over expression reduces the cholinergic phenotype but does not produce a frank loss of CBF cells. This phenotypic down regulation of ChAT is reminiscent of the lack of a frank CBF neuron loss in prodromal AD. Moreover, studies using mice transgenic for both the amyloid precursor protein (APP) and presenilin-1 (PS1) bearing AD-related mutations (APPswe/PS1delta9) displayed increased GAL immunoreactive fibers, neurities and plaques in cortex and hippocampus. These fin'dings provide evidence for a mechanistic relationship between amyloidosis and GAL over expression in AD. Understanding GALs role in the clinical and pathological features of AD, may lead to novel drug treatments for this disease.

Counts SE, Perez SE, Ginsberg SD, De Lacalle S, Mufson EJ. · Department of Neurological Sciences, Rush-Presbyterian-St. Luke's Medical Center, 2242 West Harrison Street, Chicago, IL 60612, USA. · Mol Interv. · Pubmed #14993421 links to  free full text

Abstract: Galanin (GAL) and GAL receptors (GALR) are overexpressed in limbic brain regions associated with cognition in Alzheimer disease (AD). The functional consequences of this overexpression are unclear. Because GAL inhibits cholinergic transmission and restricts long-term potentiation in the hippocampus, GAL overexpression may exacerbate clinical features of AD. In contrast, GAL expression increases in response to neuronal injury, and galaninergic hyperinnervation prevents the decreased production of protein phosphatase 1 subtype mRNAs in cholinergic basal forebrain neurons in AD. Thus, GAL may also be neuroprotective for AD. Further elucidation of GAL activity in selectively vulnerable brain regions will help gauge the therapeutic potential of GALR ligands for the treatment of AD.

Counts SE, Perez SE, Kahl U, Bartfai T, Bowser RP, Deecher DC, Mash DC, Crawley JN, Mufson EJ. · Department of Neurological Sciences, Rush-Presbyterian-St. Luke's Medical Center, 2242 West Harrison Street, Chicago, IL 60612, USA. · CNS Drug Rev. · Pubmed #11830760 No free full text.

Abstract: The neuropeptide galanin (GAL) is widely distributed in the mammalian CNS. Several lines of evidence suggest that GAL may play a critical role in cognitive processes such as memory and attention through an inhibitory modulation of cholinergic basal forebrain activity. Furthermore, GAL fibers hyperinnervate remaining cholinergic basal forebrain neurons in Alzheimer's disease (AD). This suggests that GAL activity impacts cholinergic dysfunction in advanced AD. Pharmacological and in vitro autoradiographic studies indicate the presence of heterogeneous populations of GAL receptor (GALR) sites in the basal forebrain which bind GAL with both high and low affinity. Interestingly, we have recently observed that GALR binding sites increase in the anterior basal forebrain in late-stage AD. Three G protein-coupled GALRs have been identified to date that signal through a diverse array of effector pathways in vitro, including adenylyl cyclase inhibition and phospholipase C activation. The repertoire and distribution of GALR expression in the basal forebrain remains unknown, as does the nature of GAL and GALR plasticity in the AD basal forebrain. Recently, GAL knockout and overexpressing transgenic mice have been generated to facilitate our understanding of GAL activity in basal forebrain function. GAL knockout mice result in fewer cholinergic basal forebrain neurons and memory deficits. On the other hand, mice overexpressing GAL display hyperinnervation of basal forebrain and memory deficits. These data highlight the need to explore further the putative mechanisms by which GAL signaling might be beneficial or deleterious for cholinergic cell survival and activity within basal forebrain. This information will be critical to understanding whether pharmacological manipulation of GALRs would be effective for the amelioration of cognitive deficits in AD.

Perez SE, Lumayag S, Kovacs B, Mufson EJ, Xu S. · Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA. · Invest Ophthalmol Vis Sci. · Pubmed #18791173 No free full text.

Abstract: PURPOSE: To determine whether beta-amyloid (Abeta) deposition affects the structure and function of the retina of the APPswe/PS1DeltaE9 transgenic (tg) mouse model of Alzheimer's disease. METHODS: Retinas from 12- to 19-month old APPswe/PS1DeltaE9 tg and age-matched non-transgenic (ntg) littermates were single or double stained with thioflavine-S and antibodies against Abeta, glial fibrillar acidic protein (GFAP), microglial marker F4/80, choline acetyltransferase (ChAT), and syntaxin 1. Quantification of thioflavine-S positive plaques and retinal layer thickness was analyzed semi-quantitatively, whereas microglial cell size and levels of F4/80 immunoreactivity were evaluated using a densitometry program. Scotopic electroretinogram (ERG) recording was used to investigate retinal physiology in these mice. RESULTS: Thioflavine-S positive plaques appeared at 12 months in the retinas of APPswe/PS1DeltaE9 tg mice with the majority of plaques in the outer and inner plexiform layers. Plaques were embedded in the inner plexiform layer strata displaying syntaxin 1 and ChAT. The number and size of the plaques in the retina increased with age. Plaques appeared earlier and in greater numbers in females than in male tg littermate mice. Microglial activity was significantly increased in the retinas of APPswe/PS1DeltaE9 tg mice. Although we did not detect neuronal degeneration in the retina, ERG recordings revealed a significant reduction in the amplitudes of a- and b-waves in aged APPswe/PS1DeltaE9 tg compared to ntg littermates. CONCLUSIONS: The present findings suggest that Abeta deposition disrupts retinal structure and may contribute to the visual deficits seen in aged APPswe/PS1DeltaE9 tg mice. Whether Abeta is involved in other forms of age-related retinal dysfunction is unclear.

Perez SE, Dar S, Ikonomovic MD, DeKosky ST, Mufson EJ. · Department of Neurological Sciences, Alla V. and Solomon Jesmer Chair in Aging, Rush University Medical Center, 1735 W. Harrison Street, Suite 300, Chicago, IL 60612, USA. · Neurobiol Dis. · Pubmed #17662610 links to  free full text

Abstract: The impact of Abeta deposition upon cholinergic intrinsic cortical and striatal, as well as basal forebrain long projection neuronal systems was qualitatively and quantitatively evaluated in young (2-6 months) and middle-aged (10-16 months) APPswe/PS1DeltaE9 transgenic (tg) mice. Cholinergic neuritic swellings occurred as early as 2-3 months of age in the cortex and hippocampus and 5-6 months in the striatum of tg mice. However, cholinergic neuron number or choline acetyltransferase (ChAT) optical density measurements remained unchanged in the forebrain structures with age in APPswe/PS1DeltaE9 tg mice. ChAT enzyme activity decreased significantly in the cortex and hippocampus of middle-aged tg mice. These results suggest that Abeta deposition has age-dependent effects on cortical and hippocampal ChAT fiber networks and enzyme activity, but does not impact the survival of cholinergic intrinsic or long projection forebrain neurons in APPswe/PS1DeltaE9 tg mice.

Perez SE, Lazarov O, Koprich JB, Chen EY, Rodriguez-Menendez V, Lipton JW, Sisodia SS, Mufson EJ. · Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois 60612, USA. · J Neurosci. · Pubmed #16267229 links to  free full text

Abstract: Alzheimer's disease (AD) is often accompanied by extrapyramidal signs attributed to nigrostriatal dysfunction. The association between amyloid deposition and nigrostriatal degeneration is essentially unknown. We showed previously that the striatum and the substantia nigra of transgenic mice harboring familial AD (FAD)-linked APPswe/PS1DeltaE9 mutants exhibit morphological alterations accompanied by amyloid-beta (Abeta) deposition (Perez et al., 2004). In the present study, we further investigated the interaction between Abeta deposition and dopaminergic nigrostriatal dysfunction, by correlating morphological and biochemical changes in the nigrostriatal pathway with amyloid deposition pathology in the brains of 3- to 17-month-old APPswe/PS1DeltaE9 transgenic mice and age-matched wild-type controls. We show that Abeta deposition is pronounced in the striatum of APPswe/PS1DeltaE9 mice at 6 months of age, and the extent of deposition increases in an age-dependent manner. Tyrosine hydroxylase (TH)-positive dystrophic neurites with rosette or grape-like cluster disposition are observed adjacent to Abeta plaques and display multilaminar, multivesicular, and dense-core bodies as well as mitochondria. In addition, an age-dependent increase of TH protein levels are shown in nigral cells in these mutant mice. Using HPLC analysis, we found a reduction in the dopamine metabolite DOPAC in the striatum of these mice. These findings show a close association between amyloid deposition and nigrostriatal pathology and suggest that altered FAD-linked amyloid metabolism impairs, at least in part, the function of dopaminergic neurons.