Shaddock (Citrus maxima) peels extract restores cognitive function, cholinergic and purinergic enzyme systems in scopolamine-induced amnesic rats.

This study investigated the effect of shaddock peels extract on cognitive function in scopolamine-induced amnesic rats. Wistar rats were pretreated with shaddock peels extract (50 and 100 mg/kg) and donepezil (5 mg/kg) for fourteen days via oral administration. Memory impairment was induced at the end of the treatment period via a single intraperitoneal administration of scopolamine (3 mg/kg). Thereafter, the animals were subjected to behavioral studies (Morris water maze and Y-maze tests). Finally, the rats were sacrificed and the hippocampus of the rat's brain was isolated for biochemical analyses. The results showed a significant decrease in memory and cognitive function as revealed by Morris water maze and Y-maze tests in scopolamine-induced rats which were reversed by shaddock peels extract. Also, there was a significant decrease in the activity of adenosine monophosphohydrolase (AMPase) with a simultaneous increase in activities of adenosine deaminase (ADA), adenosine triphosphate diphosphohydrolase (ATPdase), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in scopolamine-induced rats when compared with the control. Besides, a significant increase in malondialdehyde (MDA) and reactive oxygen species (ROS) levels were observed in scopolamine-induced rats. However, donepezil or shaddock peels extract (50 and 100 mg/kg) caused a significant inhibitory effect on AChE, and ADA activities when compared to scopolamine-induced rats. Rats treated with shaddock peels extract also showed a significant reduction in MDA and ROS levels compared to scopolamine-induced rats. Therefore, our findings showed that the cognitive-enhancing effects of shaddock peels extract could be due to antioxidant activities and modulation of some enzymes linked with cognitive dysfunction.

Integrated transcriptomic and proteomic analysis indicated that neurotoxicity of rats with chronic fluorosis may be in mechanism involved in the changed cholinergic pathway and oxidative stress.

BACKGROUND: To reveal the underling molecular mechanism in brain damage induced by chronic fluorosis, the neurotoxicity and its correlation were investigated by transcriptomics and proteomics. METHODS: Sprague-Dawley rats were treated with fluoride at different concentrations (0, 5, 50 and 100 ppm, prepared by NaF) for 3 months. Spatial learning and memory were evaluated by Morris water maze test; neuronal morphological change in the hippocampus was observed using Nissl staining; and the level of oxidative stress including reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) were detected by biological methods. The high-throughput transcriptome sequencing (RNA-Seq) and tandem mass tag (TMT) proteomic sequencing were performed to detect the expression of differentially expressed genes and proteins, respectively. RESULTS: The results showed that compared with control group, rats exposed to high-dose fluoride exhibited declined abilities of learning and memory, decreased SOD activity and increased ROS and MDA levels, with lighter colored Nissl bodies. A total of 28 important differentially expressed genes (DEGs) were screened out by transcriptomics. Then, functional enrichment analyses showed that upregulated proteins enriched in cellular transport, while downregulated proteins enriched in synapse-related pathways. Thirteen corresponding DEGs and DAPs (cor-DEGs-DAPs) were identified by differential expressions selected with positively correlated genes/proteins, most of which were related to neurodegenerative changes and oxidative stress response. CONCLUSION: These results provide new omics evidence that rats chronically exposed to high-dose fluoride can induce neurotoxicity in the brains through changes in the cholinergic pathway and oxidative stress.

Toxicokinetics of the neonicotinoid insecticide imidacloprid in rainbow trout (Oncorhynchus mykiss).

Studies were conducted to determine the distribution and elimination of imidacloprid (IMI) in rainbow trout. Animals were injected with a low (47.6 µg/kg), medium (117.5 µg/kg) or high (232.7 µg/kg) dose directly into the bloodstream and allowed to depurate. The fish were then sampled to characterize the loss of IMI from plasma and its appearance in expired water (all dose groups) and urine (medium dose only). In vitro biotransformation of IMI was evaluated using trout liver S9 fractions. Mean total clearance (CLT) values determined by non-compartmental analysis of plasma time-course data were 21.8, 27.0 and 19.5 mL/h/kg for the low, medium and high dose groups, respectively. Estimated half-lives for the same groups were 67.0, 68.4 and 68.1 h, while fitted values for the steady-state volume of distribution (VSS) were 1.72, 2.23 and 1.81 L/kg. Branchial elimination rates were much lower than expected, suggesting that IMI is highly bound in blood. Renal clearance rates were greater than measured rates of branchial clearance (60% of CLT in the medium dose group), possibly indicating a role for renal membrane transporters. There was no evidence for hepatic biotransformation of IMI. Collectively, these findings suggest that IMI would accumulate in trout in continuous waterborne exposures.

Acrylamide toxicity and cholinergic nervous system.

Acrylamide (ACR) is a chemical compound, that forms in starchy food products during cooking at high-temperatures, including frying, baking, and roasting. ACR is a known lethal neurotoxin. The presented review suggests that the mechanism of ACR's neurotoxicity may be related to an impaired cholinergic transmission in the central and peripheral nervous system and redox imbalance. These may not only affect ongoing brain functions but also participate in etiology of neurodegeneration.

Sublethal doses of neonicotinoid imidacloprid can interact with honey bee chemosensory protein 1 (CSP1) and inhibit its function.

As a frequently used neonicotinoid insecticide, imidacloprid can impair the chemoreceptive behavior of honey bees even at sublethal doses, while the physiochemical mechanism has not been further revealed. Here, multiple fluorescence spectra, thermodynamic method, and molecular docking were used to study the interaction and the functional inhibition of imidacloprid to the recombinant CSP1 protein in Asian honey bee, Apis cerana. The results showed that the fluorescence intensity (λem = 332 nm) of CSP1 could be significantly quenched by imidacloprid in a dynamic mode. During the quenching process, ΔH > 0, ΔS > 0, indicating that the acting forces of imidacloprid with CSP1 are mainly hydrophobic interactions. Synchronous fluorescence showed that the fluorescence of CSP1 was mainly derived from tryptophan, and the hydrophobicity of tryptophan decreased with the increase of imidacloprid concentration. Molecular docking predicted the optimal pose and the amino acid composition of the binding process. Circular dichroism (CD) spectra showed that imidacloprid reduced the α-helix of CSP1 and caused the extension of the CSP1 peptide chain. In addition, the binding of CSP1 to floral scent ß-ionone was inhibited by nearly 50% of the apparent association constant (KA) in the presence of 0.28-2.53 ng/bee of imidacloprid, and the inhibition rate of nearly 95% at 3.75 ng/bee of imidacloprid at sublethal dose level. This study initially revealed the molecular physiochemical mechanism that sublethal doses of neonicotinoid still interact and inhibit the physiological function of the honey bees' chemoreceptive system.

Midazolam-ketamine dual therapy stops cholinergic status epilepticus and reduces Morris water maze deficits.

OBJECTIVE: Pharmacoresistance remains an unsolved therapeutic challenge in status epilepticus (SE) and in cholinergic SE induced by nerve agent intoxication. SE triggers a rapid internalization of synaptic γ-aminobutyric acid A (GABAA ) receptors and externalization of N-methyl-d-aspartate (NMDA) receptors that may explain the loss of potency of standard antiepileptic drugs (AEDs). We hypothesized that a drug combination aimed at correcting the consequences of receptor trafficking would reduce SE severity and its long-term consequences. METHODS: A severe model of SE was induced in adult Sprague-Dawley rats with a high dose of lithium and pilocarpine. The GABAA receptor agonist midazolam, the NMDA receptor antagonist ketamine, and/or the AED valproate were injected 40 min after SE onset in combination or as monotherapy. Measures of SE severity were the primary outcome. Secondary outcomes were acute neuronal injury, spontaneous recurrent seizures (SRS), and Morris water maze (MWM) deficits. RESULTS: Midazolam-ketamine dual therapy was more efficient than double-dose midazolam or ketamine monotherapy or than valproate-midazolam or valproate-ketamine dual therapy in reducing several parameters of SE severity, suggesting a synergistic mechanism. In addition, midazolam-ketamine dual therapy reduced SE-induced acute neuronal injury, epileptogenesis, and MWM deficits. SIGNIFICANCE: This study showed that a treatment aimed at correcting maladaptive GABAA receptor and NMDA receptor trafficking can stop SE and reduce its long-term consequences. Early midazolam-ketamine dual therapy may be superior to monotherapy in the treatment of benzodiazepine-refractory SE.

Pain sensitivity following loss of cholinergic basal forebrain (CBF) neurons in the rat.

Flexion/withdrawal reflexes are attenuated by spinal, intracerebroventricular (ICV) and systemic delivery of cholinergic agonists. In contrast, some affective reactions to pain are suppressed by systemic cholinergic antagonism. Attention to aversive stimulation can be impaired, as is classical conditioning of fear and anxiety to aversive stimuli and psychological activation of stress reactions that exacerbate pain. Thus, in contrast to the suppressive effects of cholinergic agonism on reflexes, pain sensitivity and affective reactions to pain could be attenuated by reduced cerebral cholinergic activation. This possibility was evaluated in the present study, using an operant test of escape from nociceptive thermal stimulation (10 °C and 44.5 °C) before and after destruction of basal forebrain cholinergic neurons. ICV injection of 192 IgG-saporin produced widespread loss of basal forebrain cholinergic innervation of the cerebral cortex and hippocampus. Post-injection, escape from thermal stimulation was decreased with no indication of recovery for upto 19 weeks. Also, the normal hyperalgesic effect of sound stress was absent after ICV 192-sap. Effects of cerebral cholinergic denervation or stress on nociceptive licking and guarding reflexes were not consistent with the effects on operant escape, highlighting the importance of evaluating pain sensitivity of laboratory animals with an operant behavioral test. These results reveal that basal forebrain cholinergic transmission participates in the cerebral processing of pain, which may be relevant to the pain sensitivity of patients with Alzheimer's disease who have prominent degeneration of basal forebrain cholinergic neurons.

Neurobehavioral impairments caused by developmental imidacloprid exposure in zebrafish.

BACKGROUND: Neonicotinoid insecticides are becoming more widely applied as organophosphate (OP) insecticides are decreasing in use. Because of their relative specificity to insect nicotinic receptors, they are thought to have reduced risk of neurotoxicity in vertebrates. However, there is scant published literature concerning the neurobehavioral effects of developmental exposure of vertebrates to neonicotinoids. METHODS: Using zebrafish, we investigated the neurobehavioral effects of developmental exposure to imidacloprid, a prototypic neonicotinoid pesticide. Nicotine was also administered for comparison. Zebrafish were exposed via immersion in aqueous solutions containing 45 µM or 60 µM of imidacloprid or nicotine (or vehicle control) from 4h to 5d post fertilization. The functional effects of developmental exposure to both imidacloprid and nicotine were assessed in larvae using an activity assay and during adolescence and adulthood using a battery of neurobehavioral assays, including assessment of sensorimotor response and habituation in a tactile startle test, novel tank swimming, and shoaling behavior. RESULTS: In larvae, developmental imidacloprid exposure at both doses significantly decreased swimming activity. The 5D strains of zebrafish were more sensitive to both nicotine and imidacloprid than the AB* strain. In adolescent and adult fish, developmental exposure to imidacloprid significantly decreased novel tank exploration and increased sensorimotor response to startle stimuli. While nicotine did not affect novel tank swimming, it increased sensorimotor response to startle stimuli at the low dose. No effects of either compound were found on shoaling behavior or habituation to a startling stimulus. DISCUSSION: Early developmental exposure to imidacloprid has both early-life and persisting effects on neurobehavioral function in zebrafish. Its developmental neurotoxicity should be further investigated.

Roundup® exposure promotes gills and liver impairments, DNA damage and inhibition of brain cholinergic activity in the Amazon teleost fish Colossoma macropomum.

Roundup Original® (RD) is a glyphosate-based herbicide used to control weeds in agriculture. Contamination of Amazon waters has increased as a consequence of anthropogenic pressure, including the use of herbicides as RD. The central goal of this study was to evaluate the toxic effects of RD on juveniles of tambaqui (Colossoma macropomum). Our findings show that biomarkers in tambaqui are organ specific and dependent on RD concentration. Alterations in gills structural and respiratory epithelium were followed by changes in hematological parameters such as concentration of hemoglobin, particularly in fish exposed to the higher concentration tested (75% of RD LC50 96 h). In addition, both RD concentrations affected the biotransformation process in gills of tambaqui negatively. Instead, liver responses suggest that a production of reactive oxygen species (ROS) occurred in fish exposed to RD, particularly in the animals exposed to 75% RD, as seen by imbalances in biotransformation and antioxidant systems. The increased DNA damage observed in red blood cells of tambaqui exposed to RD is in agreement with this hypothesis. Finally, both tested sub-lethal concentrations of RD markedly inhibited the cholinesterase activity in fish brain. Thus, we can suggest that RD is potentially toxic to tambaqui and possibly to other tropical fish species.

Enhanced consumption of salient solutions following pedunculopontine tegmental lesions.

Rats with lesions of the pedunculopontine tegmental nucleus (PPTg) reliably overconsume high concentration sucrose solution. This effect is thought to be indicative of response-perseveration or loss of behavioral control in conditions of high excitement. While these theories have anatomical and behavioral support, they have never been explicitly tested. Here, we used a contact lickometer to examine the microstructure of drinking behavior to gain insight into the behavioral changes during overconsumption. Rats received either excitotoxic (ibotenic acid) damage to all PPTg neuronal subpopulations or selective depletion of the cholinergic neuronal sub-population (diphtheria toxin-urotensin II (Dtx-UII) lesions). We offered rats a variety of pleasant, neutral and aversive tastants to assess the generalizability and specificity of the overconsumption effect. Ibotenic-lesioned rats consumed significantly more 20% sucrose than sham controls, and did so through licking significantly more times. However, the behavioral microstructure during overconsumption was unaffected by the lesion and showed no indications of response-perseveration. Furthermore, the overconsumption effect did not generalize to highly consumed saccharin. In contrast, while only consuming small amounts of quinine solution, ibotenic-lesioned rats had significantly more licks and bursts for this tastant. Selective depletion of cholinergic PPTg neurons had no effect on consumption of any tastant. We then assessed whether it is the salience of the solution which determines overconsumption by ibotenic-lesioned rats. While maintained on free-food, ibotenic-lesioned rats had normal consumption of sucrose and hypertonic saline. After mild food deprivation ibotenic PPTg-lesioned rats overconsumed 20% sucrose. Subsequently, after dietary-induced sodium deficiency, lesioned rats consumed significantly more saline than controls. These results establish that it is the salience of the solution which is the determining factor leading to overconsumption following excitotoxic PPTg lesion. They also find no support for response-perseveration contributing to this effect. Results are discussed in terms of altered dopamine (DA) and salience signaling.

Risks of neonicotinoid insecticides to honeybees.

The European honeybee, Apis mellifera, is an important pollinator of agricultural crops. Since 2006, when unexpectedly high colony losses were first reported, articles have proliferated in the popular press suggesting a range of possible causes and raising alarm over the general decline of bees. Suggested causes include pesticides, genetically modified crops, habitat fragmentation, and introduced diseases and parasites. Scientists have concluded that multiple factors in various combinations-including mites, fungi, viruses, and pesticides, as well as other factors such as reduction in forage, poor nutrition, and queen failure-are the most probable cause of elevated colony loss rates. Investigators and regulators continue to focus on the possible role that insecticides, particularly the neonicotinoids, may play in honeybee health. Neonicotinoid insecticides are insect neurotoxicants with desirable features such as broad-spectrum activity, low application rates, low mammalian toxicity, upward systemic movement in plants, and versatile application methods. Their distribution throughout the plant, including pollen, nectar, and guttation fluids, poses particular concern for exposure to pollinators. The authors describe how neonicotinoids interact with the nervous system of honeybees and affect individual honeybees in laboratory situations. Because honeybees are social insects, colony effects in semifield and field studies are discussed. The authors conclude with a review of current and proposed guidance in the United States and Europe for assessing the risks of pesticides to honeybees.

Selective immunotoxic lesions of basal forebrain cholinergic cells: effects on learning and memory in rats.

Male Long-Evans rats were given injections of either 192 IgG-saporin, an apparently selective toxin for basal forebrain cholinergic neurons (LES), or vehicle (CON) into either the medial septum and vertical limb of the diagonal band (MS/VDB) or bilaterally into the nucleus basalis magnocellularis and substantia innominata (nBM/SI). Place discrimination in the Morris water maze assessed spatial learning, and a trial-unique matching-to-place task in the water maze assessed memory for place information over varying delays. MS/VDB-LES and nBM/SI-LES rats were not impaired relative to CON rats in acquisition of the place discrimination, but were mildly impaired relative to CON rats in performance of the memory task even at the shortest delay, suggesting a nonmnemonic deficit. These results contrast with effects of less selective lesions, which have been taken to support a role for basal forebrain cholinergic neurons in learning and memory.

Neurotranmission systems as targets for toxicants: a review.

Neurotransmitters are chemicals that transmit impulses from one nerve to another or from nerves to effector organs. Numerous neurotransmitters have been described in mammals, amongst them acetylcholine, amino acids, amines, peptides and gases. Toxicants may interact with various parts of neurotransmission systems, including synthetic and degradative enzymes, presynaptic vesicles and the specialized receptors that characterize neurotransmission systems. Important toxicants acting on the cholinergic system include the anticholinesterases (organophosphates and carbamates) and substances that act on receptors such as nicotine and the neonicotinoid insecticides, including imidacloprid. An important substance acting on the glutamatergic system is domoic acid, responsible for amnesic shellfish poisoning. 4-Aminobutyric acid (GABA) and glycine are inhibitory neurotransmitters and their antagonists, fipronil (an insecticide) and strychnine respectively, are excitatory. Abnormalities of dopamine neurotransmission occur in Parkinson's disease, and a number of substances that interfere with this system produce Parkinsonian symptoms and clinical signs, including notably 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which is the precursor of 1-methyl-4-phenylpyridinium. Fewer substances are known that interfere with adrenergic, histaminergic or seroninergic neurotransmission, but there are some examples. Among peptide neurotransmission systems, agonists of opioids are the only well-known toxic compounds.

Suspected muscarinic mushroom intoxication in a cat.

A 3-year-old domestic shorthair cat was witnessed ingesting mushrooms and developed signs of muscarine intoxication. After stabilisation and treatment with atropine the cat recovered well and was discharged from hospital in 2 days. This report describes the features and successful management of this unusual toxicosis in cats.

Tramadol safety--cholinergic system of rat brain without nociception.

In the present investigation, changes in the levels of acetylcholinesterase (AChE) activity, acetylcholine (ACh) content, and the activity levels of plasma (PChE) and erythrocyte (EChE) cholinesterases as representatives of pseudocholinesterases were examined in different areas of the rat brain during the administration of the synthetic opioid analgesic drug tramadol (Ultram) without induction of pain. Male adult Wistar rats weighing 150 +/- 20 g were used. Tramadol was injected subcutaneously (s.c.) into the rats at 0, 24 and 48 h, and the changes in the above cholinergic parameters were recorded after the completion of 3, 6, 12, 24, 48 and 72 h. Following administration of single dose (for rats sacrificed at 24 h) and multiple doses (for rats sacrificed at 48 and 72 h) of tramadol, the ACh content showed an increase in all brain areas. Concurrently, the AChE activity was found to decrease in all the areas. PChE and EChE showed higher activity levels, with EChE showing a higher level of activity than PChE. The levels of all the parameters examined returned towards the control levels by about 24 h after the administration of single dose of tramadol. However, the ACh levels showed an elevation at 48 and 72 h (following double and triple doses, respectively). The AChE activity levels also showed a simultaneous increase at 48 and 72 h, presumably to balance the increase in ACh levels on longer treatment with tramadol. The observed changes in the cholinergic segment presumably do not cause any physiological lesion since they reverted to control levels after the time limit of change under tramadol influence. This observation indicates that tramadol can be administered safely both under nociceptive and non-nociceptive conditions.

Histamine release in the basal forebrain mediates cortical activation through cholinergic neurons.

The basal forebrain (BF) is a key structure in regulating both cortical activity and sleep homeostasis. It receives input from all ascending arousal systems and is particularly highly innervated by histaminergic neurons. Previous studies clearly point to a role for histamine as a wake-promoting substance in the BF. We used in vivo microdialysis and pharmacological treatments in rats to study which electroencephalogram (EEG) spectral properties are associated with histamine-induced wakefulness and whether this wakefulness is followed by increased sleep and increased EEG delta power during sleep. We also investigated which BF neurons mediate histamine-induced cortical activation. Extracellular BF histamine levels rose immediately and remained constant throughout a 6 h period of sleep deprivation, returning to baseline levels immediately afterward. During the spontaneous sleep-wake cycle, we observed a strong correlation between wakefulness and extracellular histamine concentrations in the BF, which was unaffected by the time of day. The perfusion of histamine into the BF increased wakefulness and cortical activity without inducing recovery sleep. The perfusion of a histamine receptor 1 antagonist into the BF decreased both wakefulness and cortical activity. Lesioning the BF cholinergic neurons abolished these effects. Together, these results show that activation of the cholinergic BF by histamine is important in sustaining a high level of cortical activation, and that a lack of activation of the cholinergic BF by histamine may be important in initiating and maintaining nonrapid eye movement sleep. The level of histamine release is tightly connected to behavioral state, but conveys no information about sleep pressure.

Oral tremor induced by galantamine in rats: a model of the parkinsonian side effects of cholinomimetics used to treat Alzheimer's disease.

Anticholinesterases are the most common treatment for Alzheimer's disease, and, in recent years, a new group of cholinesterase inhibitors (i.e. rivastigmine, galantamine, and donepezil) has become available. Although these drugs improve cognitive symptoms, they also can induce or exacerbate parkinsonian symptoms, including tremor. The present studies were conducted to determine if galantamine induces tremulous jaw movements, a rodent model of parkinsonian tremor, and to investigate whether these oral motor impairments can be reversed by co-administration of adenosine A(2A) antagonists. The first experiment demonstrated that systemic injections of galantamine (0.75-6.0 mg/kg I.P.) induced a dose-related increase in tremulous jaw movements in rats. In a second study, co-administration of the muscarinic antagonist scopolamine (0.0156-0.25 mg/kg I.P.) produced a dose dependent suppression of tremulous jaw movements induced by a 3.0 mg/kg dose of galantamine, indicating that galantamine induces these tremulous oral movements through actions on muscarinic acetylcholine receptors. In two additional studies, analyses of freeze-frame video and electromyographic activity recorded from the lateral temporalis muscle indicated that the local frequency of these galantamine-induced jaw movements occurs in the 3-7 Hz frequency range that is characteristic of parkinsonian tremor. In the final experiment, the adenosine A(2A) antagonist MSX-3 significantly attenuated the tremulous jaw movements induced by the 3.0mg/kg dose of galantamine, which is consistent with the hypothesis that co-administration of adenosine A(2A) antagonists may be beneficial in reducing parkinsonian motor impairments induced by anticholinesterase treatment.

Nicotine exposure during the third trimester equivalent of human gestation: time course of effects on the central cholinergic system of rats.

Up to 22% of pregnant women smoke, which constitutes a major health concern. Nicotine, a cholinergic agonist, causes deleterious effects on brain development. However, most studies investigate its effects during rodents' gestation, which corresponds, in terms of neural development, to the first two trimesters of human gestation. Here, we focused on effects of nicotine on the brain cholinergic system during the third trimester equivalent of human gestation. From the 2nd to the 19th day of lactation, dams were exposed either to nicotine (6 mg/kg/day) or to saline via sc osmotic minipumps. Offspring were sacrificed during exposure (PN15, PN, postnatal) or at 2 days (PN21), 11 days (PN30), or 10 weeks (PN90) of withdrawal. In the cerebral cortex, midbrain, and hippocampus, we assessed nicotinic acetylcholine receptor (nAChR) binding, [(3)H]hemicholinium-3 (HC-3) binding to the high-affinity choline transporter, choline acetyltransferase (ChAT), and acetylcholinesterase (AChE) activities. Nicotine-exposed offspring presented nAChR upregulation during exposure in all brain regions, reduced HC-3 binding during and 11 days postexposure, and increased HC-3 binding on PN90. Effects on ChAT and AChE were dependent on the brain region and restricted to the withdrawal period: There were increased activities in the midbrain on PN30. In the hippocampus, AChE as reduced on PN30, whereas, for ChAT, the decrease was followed by late-emergent increased activity. These data indicate that maternal nicotine exposure during the third trimester equivalent of human gestation promotes cholinergic system alterations in the offspring's brain. In addition, detrimental effects are observable even long after the exposure has been interrupted.

Molsidomine modulates the cNOS activity in an experimental model of cholinergic damage induced by 192-IgG saporin.

The aim of this work was to study the effect of molsidomine (MOLS), a nitric oxide (NO) donor, on the nitrergic system changes in an experimental model of cholinergic damage induced by 192 IgG saporin (SAP). Male rats were injured by intraseptal administration of SAP (0.22 µg), after seven days, rats were administered with MOLS (4 mg/kg, i.p.) 60 min before sacrifice. Prefrontal cortex (PC), striatum (S) and hippocampus (HC) were dissected out. Results showed significant recovery of the constitutive NOS activity (cNOS) in PC and S regions by MOLS but not in HC compared against controls. SAP reduced the cellular population in the lesion site and MOLS was able to avoid the progression of damage in this area. NO donor is able to modulate the nitrergic status in an experimental model induced by SAP.

The effects of neonatal forebrain cholinergic lesion on adult hippocampal neurogenesis.

Previous work in our laboratory indicated that cholinergic denervation by intraventricular infusion of 192-IgG-saporin on postnatal day 7 (N192S) reduced the number of cells in the dentate gyrus expressing doublecortin, a marker for immature neuroblasts. In addition, there was a suggestion that N192S impaired the neurogenic response to environmental enrichment (EE). The purpose of the present study was to further characterize the impact of N192S on the proliferation, differentiation and survival of newborn cells in the dentate gyrus. After 42 days in EE or standard housing, all rats received injections of 5-bromo-2-deoxyuridine (BrdU) to label dividing cells. They were sacrificed either one day (to assess cell proliferation) or 28 days later (to assess survival and differentiation of BrdU-labelled cells). EE failed to increase neurogenesis, thereby preventing determination of the effects of N192S on EE-induced neurogenesis. However, N192S by itself reduced the number of BrdU(+) cells 1 day after BrdU exposure, but did not alter the number of cells expressing the cell cycle marker Ki-67. The number of BrdU(+) cells 28 days after BrdU exposure was not affected by N192S. Confocal analysis of BrdU(+) cells double-immunofluorescently stained to detect NeuN or S100B indicated that N192S did not alter the proportion of new cells that adopted a neuronal or glial identity. The most plausible explanation for these results is that N192S accelerates the death of newborn cells, but does not change their overall survival rate or phenotypic differentiation.