4-aminopyrrolidine-2-4-dicarboxylic-acid and Disease-Models--Animal

This study aimed to study the protective effect of (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate (2R,4R-APDC), a selective metabotropic glutamate receptor agonist, against hippocampal neuronal apoptosis induced by seizures in a rat model of pilocarpine-induced epilepsy. The Morris water maze test was used to assess the spatial memory abilities of epileptic rats with or without 2R,4R-APDC treatment. TUNEL assay was performed to examine neuronal apoptosis in hippocampus. Western blot was conducted to evaluate changes in the levels of caspase-3 and caspase-9 in hippocampus. Real-time PCR was used to determine the levels of microRNA-128 (miR-128) in hippocampus. The results of the Morris water maze test showed that the 2R,4R-APDC treatment reduced the escape latencies and swimming lengths of rats after seizures. The TUNEL assay showed that 2R,4R-APDC significantly counteracted seizure-induced cell apoptosis. The western blot confirmed this finding, demonstrating that the levels of cleaved caspase-3 and cleaved caspase-9 were potently decreased by 2R,4R-APDC in rat hippocampus after seizures. In addition, 2R,4R-APDC upregulated miR-128 expression levels in the hippocampus. A miR-128 mimic or inhibitor decreased or increased the percentage of TUNEL-positive cells in rats after seizures and 2R,4R-APDC treatment, respectively. The levels of both cleaved caspase-3 and cleaved caspase-9 were decreased in hippocampus exposed to the miR-128 mimic, whereas they were markedly increased in miR-128 inhibitor-treated hippocampus. In conclusion, 2R,4R-APDC protected hippocampal cells from cell apoptosis after seizures, possibly by upregulating miR-128.

Topics: Animals; Animals, Newborn; Disease Models, Animal; Excitatory Amino Acid Agonists; Hippocampus; Male; Memory; MicroRNAs; Proline; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate; Seizures; Up-Regulation

To characterize an alcohol and high fat diet induced chronic pancreatitis rat model that mimics poor human dietary choices.. Experimental rats were fed a modified Lieber-DeCarli alcohol (6%) and high-fat (65%) diet (AHF) for 10 wk while control animals received a regular rodent chow diet. Weekly behavioral tests determined mechanical and heat sensitivity. In week 10 a fasting glucose tolerance test was performed, measuring blood glucose levels before and after a 2 g/kg bodyweight intraperitoneal (i.p.) injection of glucose. Post mortem histological analysis was performed by staining pancreas and liver tissue sections with hematoxylin and eosin. Pancreas sections were also stained with Sirius red and fast green to quantify collagen content. Insulin-expressing cells were identified immunohistochemically in separate sections. Tissue staining density was quantified using Image J software. After mechanical and heat sensitivity became stable (weeks 6-10) in the AHF-fed animals, three different drugs were tested for their efficacy in attenuating pancreatitis associated hypersensitivity: a Group II metabotropic glutamate receptor specific agonist (2R,4R)-4-Aminopyrrolidine-2,4-dicarboxylate (APDC, 3 mg/kg, ip; Tocris, Bristol, United Kingdom), nociceptin (20, 60, 200 nmol/kg, ip; Tocris), and morphine sulfate (3 mg/kg, μ-opioid receptor agonist; Baxter Healthcare, Deerfield, IL, United States).. Histological analysis of pancreas and liver determined that unlike control rats, AHF fed animals had pancreatic fibrosis, acinar and beta cell atrophy, with steatosis in both organs. Fat vacuolization was significantly increased in AHF fed rats (6.4% ± 1.1% in controls vs 23.8% ± 4.2%, P < 0.05). Rats fed the AHF diet had reduced fasting glucose tolerance in week 10 when peak blood glucose levels reached significantly higher concentrations than controls (127.4 ± 9.2 mg/dL in controls vs 161.0 ± 8.6 mg/dL, P < 0.05). This concurred with a 3.5 fold higher incidence of single and small 2-10 cell insulin-positive cell clusters (P < 0.05). Insulin expressing islet of Langerhans cells appeared hypertrophied while islet number and area measurements were not different from controls. Weekly behavioral tests determined that mechanical and heat sensitivities were significantly increased by 4 wk on AHF diet compared to controls. Hypersensitivity was attenuated with efficacy similar to morphine with single dose treatment of either metabotropic glutamate receptor 2/3 agonist APDC, or nociceptin, the endogenous ligand for opioid-receptor-like 1 receptor.. The AHF diet induces a chronic alcoholic pancreatitis in rats with measurable features resembling clinical patients with chronic pancreatitis and type 3c diabetes mellitus.

Topics: Analgesics; Analgesics, Opioid; Animals; Behavior, Animal; Blood Glucose; Diabetes Mellitus; Diet, High-Fat; Disease Models, Animal; Ethanol; Excitatory Amino Acid Agonists; Humans; Hyperalgesia; Liver; Male; Morphine; Nociceptin; Nociception; Opioid Peptides; Pain Threshold; Pancreas; Pancreatitis, Alcoholic; Proline; Rats, Inbred F344; Receptors, Metabotropic Glutamate; Time Factors; Visceral Pain

The widely-held assumption was that oxidative stress does not occur during seizures in the immature brain. The major finding of the present study concerns evidence of oxidative stress in the brain of immature rats during seizures induced by DL-homocysteic acid. Seizures were induced in 12-day-old rats by bilateral intracerebroventricular infusion of DL-homocysteic acid (DL-HCA, 600 nmol/side) and oxidative stress was evaluated by in situ detection of superoxide anion (O(2)·(-)). Using hydroethidine (Het) method, the fluorescent signal of the oxidized products of Het (reflecting O(2)·(-) production) significantly increased (by 50%-60%) following 60 min lasting seizures in all the studied structures, namely CA1, CA3 and dentate gyrus of the hippocampus, cerebral cortex and thalamus. The enhanced O(2)·(-) production was substantially attenuated or completely prevented by substances providing an anticonvulsant effect, namely by a competitive NMDA receptor antagonist AP7, a highly selective and potent group II metabotropic glutamate receptor (mGluR) agonist 2R,4R-APDC and highly selective group III mGluR, subtype 8 agonist (S)-3,4-DCPG. Complete protection was achieved by two SOD mimetics Tempol and MnTMPYP which strongly suggest that the increased fluorescent signal reflects O(2)·(-) formation. In addition, both scavengers provided a partial protection against brain damage associated with the present model of seizures. Signs of neuronal degeneration, as evaluated by Fluoro-Jade B staining, were detected at 4h following the onset of seizures. The present findings thus suggest that the increased superoxide generation precedes neuronal degeneration and may thus play a causative role in neuronal injury. Occurrence of oxidative stress in brain of immature rats during seizures, as demonstrated in the present study, can have a clinical relevance for a novel approach to the treatment of epilepsy in children, suggesting that substances with antioxidant properties combined with the conventional therapies might provide a beneficial effect.

Topics: 2-Amino-5-phosphonovalerate; Animals; Animals, Newborn; Anticonvulsants; Brain; Disease Models, Animal; Homocysteine; Infusions, Intraventricular; Male; Metalloporphyrins; Proline; Rats; Rats, Wistar; Seizures; Statistics, Nonparametric; Superoxides; Time Factors

Diffuse brain injury (DBI) has been shown to increase the proliferation of granule cell precursors in the adult dentate gyrus (DG). However, the mechanism by which DBI-induced cell proliferation in the DG may enhance seizure susceptibility remains largely unknown.. Using bromodeoxyuridine (BrdU) immunohistochemistry, we examined the effects of group II metabotropic glutamate receptor (mGluR) agonist, 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate (2R,4R-APDC), on cell proliferation in the DG after DBI.. It has been found that 2R,4R-APDC significantly blocked DBI-induced increase in the number of BrdU-positive cells in the DG, especially in hilus. In addition, double-label immunofluorescence staining showed that treatment with APDC did not affect the differentiation of newborn cells into neurons or astrocytes. Taken together, our findings indicate that the activation of mGluR system may inhibit the DBI-induced cell proliferation in the DG, but not the differentiation of newborn cells.. It is suggested that 2R,4R-APDC has potential neuroprotection via inhibiting the aberrant neurogenesis induced by DBI, which is an important pathological basis of seizure or other abnormalities following DBI.

Topics: Animals; Brain Injuries; Cell Proliferation; Dentate Gyrus; Disease Models, Animal; Excitatory Amino Acid Agonists; Male; Nerve Regeneration; Neural Stem Cells; Neurogenesis; Neuroprotective Agents; Proline; Rats; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate

Spinal cord injury (SCI) produces an increase in extracellular excitatory amino acid (EAA) concentrations that results in glutamate receptor-mediated excitotoxic events. An important class of these receptors is the metabotropic glutamate receptors (mGluRs). mGluRs can activate a number of intracellular pathways that increase neuronal excitability and modulate neurotransmission. Group I mGluRs are known to modulate EAA release and the development of chronic central pain (CCP) following SCI; however, the role of group II and III mGluRs remains unclear. To begin evaluating group II and III mGluRs in SCI, we administered the specific agonists for group II, APDC, or group III, L-AP4, by interspinal injection immediately following SCI. Contusion injury was produced at spinal segment T10 with a New York University impactor (12.5-mm drop, 10-g rod 2 mm in diameter) in 30 adult male Sprague-Dawley rats (175-200 g). Evoked and spontaneous behavioral measures of CCP, locomotor recovery, changes in mGluR expression, and amount of spared tissue were examined. Neither APDC nor L-AP4 affected locomotor recovery or the development of thermal hyperalgesia; however, L-AP4 and APDC attenuated changes in mechanical thresholds and changes in exploratory behavior indicative of CCP. APDC- and L-AP4-treated groups had higher expression levels of mGluR2/3 at the epicenter of injury on post contusion day 28; however, there was no difference in the amount of spared tissue between treatment groups. These results demonstrate that treatment with agonists to group II and III mGluRs following SCI affects mechanical responses, exploratory behavior, and mGluR2/3 expression without affecting the amount of tissue spared, suggesting that the level of mGluR expression after SCI may modulate nociceptive responses.

Topics: Aminobutyrates; Animals; Behavior, Animal; Chronic Disease; Disease Models, Animal; Excitatory Amino Acid Agonists; Exploratory Behavior; Hyperalgesia; Male; Motor Activity; Pain Measurement; Proline; Rats; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate; Recovery of Function; Spinal Cord; Spinal Cord Injuries; Wounds, Nonpenetrating