alzheimers-disease

Pedersen AF, Kostova V, Christensen E, Veng LM, Lohals R, Knudsen GM, Aznar S (2005) Intraventricular IgG192-saporin lesions lead to altered 5-HT2A receptor levels in the hippocampus. Neuroscience 2005 Abstracts 559.17. Society for Neuroscience, Washington, DC.

Summary: Background: Alzheimer’s disease (AD) is the most frequent neurodegenerative disorder in humans. One of the traits of the disease is the presence in the brain of beta-Amyloid plaques and loss of cholinergic neurons in the basal forebrain. Other transmittersystems especially serotonin may be involved in the patophysiology of AD. Clinical studies have observed a higher incidence of depression among AD patients and a higher risk of developing dementia when diagnosed with major depression. It is known that serotonin and serotonin receptors, among them 5-HT2A receptors (5-HT2AR), are involved in depression. Interestingly, recent PET-studies have shown lower 5-HT2AR levels in entorhinal cortex and hippocampus in early stages of AD. Objectives: Our aim was to investigate whether 5-HT2AR levels were affected in the hippocampus after lesioning the cholinergic neurons in the basal forebrain, thereby highlighting a possible interaction between the serotonergic and the cholinergic transmitter systems. Methods: Intraventricular injection of 5ug IgG192-Saporin or saline in adult Wistar male rats. After 20 weeks the rats were sacrificed and the hippocampus were isolated. After homogenisation the levels of 5-HT2AR were determined by western blot. Results: Downregulation of the 5-HT2AR levels were observed after 20 weeks. 5-HT2AR levels for animals receiving IgG192-Saporin for 1, 2 and 4 weeks will also be investigated. Conclusion: Our results show a direct effect of cholinergic lesions on hippocampal 5-HT2AR. This may be explained by a compensatory effect of the serotonergic system for the loss of cholinergic input as there may be a balance between these two systems in the hippocampus.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Yamazaki Y, Jia Y, Hamaue N, Sumikawa K (2005) Nicotine-induced switch in the nicotinic cholinergic mechanisms of facilitation of long-term potentiation induction. Eur J Neurosci 22(4):845-860. doi: 10.1111/j.1460-9568.2005.04259.x

Summary: The authors investigated cellular mechanisms underlying improved cognitive function in Alzheimer’s disease patients upon the administration of nicotine. To model Alzheimer’s disease in rats, 2 µg of 192-IgG-SAP (Cat. #IT-01) was injected into the lateral cerebral ventricle. Examination of the lesioned animals suggests that nicotine promotes the induction of long-term potentiation by enhancing N-methyl-D-aspartate responses, and suppressing acetylcholine-mediated mechanisms in pyramidal cells.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Guillemin GJ, Brew BJ, Noonan CE, Takikawa O, Cullen KM (2005) Indoleamine 2,3 dioxygenase and quinolinic acid immunoreactivity in Alzheimer’s disease hippocampus. Neuropathol Appl Neurobiol 31(4):395-404. doi: 10.1111/j.1365-2990.2005.00655.x PMID: 16008823

Related Products: Quinolinic Acid Rabbit Polyclonal, Conjugated (Cat. #AB-T095)

Dudkin KN, Chueva V, Makarov FN, Bich TG, Roer AE (2005) Impairments in working memory and decision-taking processes in monkeys in a model of Alzheimer’s disease. Neurosci Behav Physiol 35(3):281-289. PMID: 15875490

Related Products: ME20.4-SAP (Cat. #IT-15), Anti-DBH-SAP (Cat. #IT-03)

Gil-Bea FJ, Garcia-Alloza M, Dominguez J, Marcos B, Ramirez MJ (2005) Evaluation of cholinergic markers in Alzheimer’s disease and in a model of cholinergic deficit. Neurosci Lett 375(1):37-41. doi: 10.1016/j.neulet.2004.10.062

Summary: Several markers of cholinergic function may be able to predict cognitive deficits due to disorders such as Alzheimer’s disease. The authors compared baseline measurements of acetylcholine, cholinacetyltransferase, and acetylcholinesterase (AChE) of rats against animals treated with 0.067 µg injections of 192-Saporin (Cat. #IT-01) into both hemispheres of the nucleus basalis magnocellularis. The results indicate that measurement of AChE activity is an inexpensive and reliable method to evaluate cholinergic function in rats as well as in humans.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Leung LS, Petropoulos S, Ma J, Shen B (2004) Cholinergic neurons in the basal forebrain participate in consciousness and general anesthesia. Neuroscience 2004 Abstracts 565.4. Society for Neuroscience, San Diego, CA.

Summary: Acetylcholine (Ach) in the brain has long been associated with consciousness. In this study, we assessed consciousness in rats by their EEG and behavioral responses to a general anesthetic. Cholinergic neurons in the nucleus basalis of Meynert (NbM) were lesioned by bilateral injection of toxin IgG192-saporin (0.15 μg at P1.4, L2.7, 7.7 mm below dura) in 10 adult male rats. Control (5 rats) had saline injected into the NbM. EEGs were recorded by electrodes placed in layer V of the frontal cortex (FC) and visual cortex (VC). Spectral analysis of the spontaneous EEGs in FC and VC during awake-immobility indicated that lesioned animals showed higher delta (0.8 to 4 Hz) and lower gamma (30- 58 Hz) power as compared to controls. Subsequent acetylcholinesterase staining (optical density) confirmed significant Ach depletion in both FC and VC, in the lesion as compared to the control group (P<0.002, Wilcoxon). When challenged with a normally subanesthetic dose of general anesthetic, the lesioned rats showed, as compared to controls, significantly longer durations of loss of righting and tail-pinch response after 5 mg/kg i.v. propofol (P<0.001), but not after 20 mg/kg i.p. pentobarbital or 2% halothane. In correspondence with the deep behavioral anesthesia, delta power at FC after propofol was significantly larger in lesioned than control rats. Lesioned rats, as compared to controls, also showed decreased locomotion (behavioral excitation) when given 2% halothane in a large chamber. In summary, a loss of Ach in the neocortex decreases the level of consciousness as indicated by increased delta and decreased gamma EEG, and by an increased sedative/ anesthetic response to propofol i.v. We suggest that patients with Alzheimer disease may show altered response to some general anesthetics.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Hawkes CA, Kar S (2004) Loss of basal forebrain cholinergic neurons by 192 igG-Saporin induces increased IGF-II/M6P receptor expression in select brain areas. Neuroscience 2004 Abstracts 92.1. Society for Neuroscience, San Diego, CA.

Summary: Alzheimer’s disease (AD) is characterized neuropathologically by the presence of extracellular amyloid plaques, intracellular neurofibrillary tangles and neuronal loss in selected brain areas, including basal forebrain cholinergic neurons, which project to the hippocampus and neocortex. Increasing evidence supports a role of the endosomal-lysosomal (EL) system in the pathophysiology of AD. A key component of the EL system is the insulin-like growth factor-II/mannose-6-phosphate (IGF-II/M6P) receptor, a single transmembrane domain glycoprotein which functions in the intracellular trafficking of lysosomal enzymes, and in the internalization of extracellular IGF-II and M6P-containing ligands. However, very little is known about the functional significance of this receptor in the brain. We examined expression of the IGF-II/M6P receptor and other markers of the EL system, at different time points following bilateral i.c.v. injection of 192 IgG-saporin. 192 IgG-saporin produced an almost complete loss of ChAT-positive neurons in the basal forebrain, as well as fibers in the hippocampus and frontal cortex, while striatal cholinergic neurons were unaffected. Western blotting and immunocytochemistry results indicate an upregulation of IGF-II/M6P receptor levels in the septum and frontal cortex. A modest increase was also observed in cathepsin D levels. The level of other EL markers, such as Rab5 and LAMP1, showed varied temporal and spatial changes. These results suggest that brain areas innervated by basal forebrain neurons, respond differently to the loss of cholinergic input and that elements of the EL system may be involved in cholinergic degeneration/compensatory responses of surviving neurons.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Kar S, Hawkes C, Jhamandas JH (2004) Selective loss of basal forebrain cholinergic neurons by 192 IgG-saporin induces activation of glycogen synthase kinase-3β activity. Neuroscience 2004 Abstracts 92.2. Society for Neuroscience, San Diego, CA.

Summary: Glycogen synthase kinase-3β (GSK-3β) is a multifunctional enzyme involved in a variety of biological events including development, glucose metabolism and cell death. Its activity is negatively regulated by phosphorylation of Ser9 and upregulated by Tyr216 phosphorylation. Activation of GSK-3β induces apoptosis in a variety of cultured neurons and the inhibitory control of its activity by Akt kinase is one of the best characterized cell survival signaling pathways. In the present study, the cholinergic immunotoxin 192-IgG saporin was used to address the potential role of GSK-3β in the degeneration of the basal forebrain cholinergic neurons which are preferentially vulnerable in Alzheimer’s disease (AD) brain. Our results show that GSK-3β colocalizes with a subset of the forebrain cholinergic neurons and that loss of these neurons is accompanied by a transient decrease in phospho-Akt and phospho-Ser9 GSK-3β levels in the basal forebrain, hippocampus and the cortex. Neither total Akt, GSK-3β, nor phospho-Tyr216 GSK-3β levels were significantly altered in the aforesaid brain regions of treated animals. These results provide the very first evidence that increased GSK-3β activity is associated with in vivo degeneration of the forebrain cholinergic neurons and thus may be involved in the loss of these neurons as observed in AD brains.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Kolasa K, Parsons D, Conger K, Harrell LE (2004) Neurotrophic modulation of cholinergic denervation and hippocampal sympathetic ingrowth following immunolesioning with 192 IgG-saporin. Neuroscience 2004 Abstracts 92.9. Society for Neuroscience, San Diego, CA.

Summary: Injection of specific cholinotoxin, 192 IgG-saporin into the medial septum (MS)of rat induces not only a selective cholinergic denervation of hippocampus (CD),but an ingrowth of peripheral sympathetic fibers, originating from the superior cervical ganglion,into the hippocampus (HSI).A similar process,in which sympathetic noradrenergic axons invade hippocampus,may also occur in Alzheimer’s disease(AD). The severity of cognitive decline in AD patients has been linked to multiple factors including cholinergic and neurotrophic factors and their receptors, which undergo selective alterations throughout the progression of AD.It is known that the sites of neurotrophin synthesis in the septo-hippocampal system are predominantly hippocampal neurons. By using 192 IgG-saporin we have been able to mimic some of the cardinal features of AD e.x.cholinergic denervation and hippocampal sympathetic ingrowth and study their effect on growth factors in dorsal hippocampus. Thus,12 weeks after injection of 192 IgG-saporin we measured neurotrophic protein and mRNA expression using Western blot and RT-PCR techniques,respectively. Choline acetyltransferase activity(ChAT)and norepinephrine(NE) concentration was also detected.There was no change in NGF,BDNF,NT3,GDNF mRNA expression,but we have found significant decrease in 240 bp and increase in 328 bp of persephin mRNA expression in CD, and “normalization” in HSI group. No significant alteration was found in NGF and persephin protein expression, but significant decrease in mature form of BDNF protein expression was found in CD, with “normalization”in HSI group.Results of the study suggest that growth factors are affected by cholinergic denervation and may play an important role in regulation and development of HSI,which might be a beneficial phenomenon for restoration of at least some cognitive function.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Ricceri L, Minghetti L, Moles A, Popoli P, Confaloni A, De Simone R, Piscopo P, Scattoni ML, di Luca M, Calamandrei G (2004) Cognitive and neurological deficits induced by early and prolonged basal forebrain cholinergic hypofunction in rats. Exp Neurol 189(1):162-172. doi: 10.1016/j.expneurol.2004.05.025

Summary: A distinctive feature of Alzheimer’s disease is the loss of cholinergic neurons in the basal forebrain (BF). The authors investigated long-term effects of BF cholinergic lesions on several parameters. Administration of 0.21 µg of 192-Saporin (Cat. #IT-01) to the third ventricle of 7 day-old rats was followed by an evaluation of protein levels and cortical EEG patterns at 6 months of age. The findings indicate that permanent neonatal BF cholinergic damage may provide a model for abnormal adult cholinergic function.

Related Products: 192-IgG-SAP (Cat. #IT-01)