Involvement of nitric oxide in granisetron improving effect on scopolamine-induced memory impairment in mice

AbstractGranisetron, a serotonin 5-HT3 receptor antagonist, widely used as an antiemetic drug following chemotherapy, has been found to improve learning and memory. In this study, effects of granisetron on spatial recognition memory and fear memory and the involvement of nitric oxide (NO) have been determined in a Y-maze and passive avoidance test. Granisetron (3, 10mg/kg, intraperitoneally) was administered to scopolamine-induced memory-impaired mice prior to acquisition, consolidation and retrieval phases, either in the presence or in the absence of a non-specific NO synthase inhibitor, l-NAME (3, 10mg/kg, intraperitoneally); a specific inducible NO synthase (iNOS) inhibitor, aminoguanidine (100mg/kg); and a NO precursor, l-arginine (750mg/kg). It is demonstrated that granisetron improved memory acquisition in a dose-dependent manner, but it was ineffective on consolidation and retrieval phases of memory. The beneficial effect of granisetron (10mg/kg) on memory acquisition was significantly reversed by l-NAME (10mg/kg) and aminoguanidine (100mg/kg); however, l-arginine (750mg/kg) did not potentiate the effect of sub-effective dose of granisetron (3mg/kg) in memory acquisition phase. It is concluded that nitric oxide is probably involved in improvement of memory acquisition by granisetron in both spatial recognition memory and fear memory.This article is part of a Special Issue entitled The Cognitive Neuroscience

Effects of nicotine and THC vapor inhalation administered by an electronic nicotine delivery system (ENDS) in male rats

BackgroundElectronic nicotine delivery systems (ENDS, e-cigarettes) are increasingly used for the self-administration of nicotine by various human populations, including previously nonsmoking adolescents. Studies in preclinical models are necessary to evaluate health impacts of ENDS including the development of nicotine addiction, effects of ENDS vehicles, flavorants and co-administered psychoactive substances such as Δ9-tetrahydrocannabinol (THC). This study was conducted to validate a rat model useful for the study of nicotine effects delivered by inhalation of vapor created by ENDS.MethodsMale Sprague-Dawley rats (N = 8) were prepared with radio telemetry devices for the reporting of temperature and activity. Experiments subjected rats to inhalation of vapor generated by an electronic nicotine delivery system (ENDS) adapted for rodents. Inhalation conditions included vapor generated by the propylene glycol (PG) vehicle, Nicotine (1, 10, 30 mg/mL in the PG) and THC (12.5, 25 mg/mL).ResultsNicotine inhalation increased spontaneous locomotion and decreased body temperature of rats. Pretreatment with the nicotinic cholinergic receptor antagonist mecamylamine (2 mg/kg, i.p.) prevented stimulant effects of nicotine vapor inhalation and attenuated the hypothermic response. Combined inhalation of nicotine and THC resulted in apparently independent effects which were either additive (hypothermia) or opposed (activity).ConclusionsThese studies provide evidence that ENDS delivery of nicotine via inhalation results in nicotine-typical effects on spontaneous locomotion and thermoregulation in male rats. Effects were blocked by a nicotinic antagonist, demonstrating mechanistic specificity. This system will therefore support additional studies of the contribution of atomizer/wick design, vehicle constituents and/or flavorants to the effects of nicotine administered by ENDS

Nitric Oxide Mediates Effects of Acute, not Chronic Naltrexone on LPS-Induced Hepatic Encephalopathy in Cirrhotic Rats

Recent studies suggest endogenous opioids and nitric oxide (NO) are involved in the pathophysiology of hepatic encephalopathy (HE). In this study, the interaction between the opioid receptors antagonist, and NO was investigated on lipopolysaccharide (LPS)-induced HE in cirrhotic rats. Male rats were divided in the sham- and bile duct ligation (BDL)-operated groups. Animals treated with saline; naltrexone (10 mg/kg, i.p.); L-NAME (3 mg/kg, i.p.); alone or in combination by naltrexone. To induce HE, LPS (1 mg/kg, i.p.) was injected one hour after the final drug treatment. Hepatic encephalopathy scoring, hepatic histology and plasma NO metabolites levels and mortality rate were recorded. Deteriorated level of consciousness and mortality after LPS administration significantly ameliorated following both acute- and chronic treatment with naltrexone in cirrhotic rats. While, acute- and chronic administration of L-NAME did not change hepatic encephalopathy scores in cirrhotic rats. The effects of acute- but not chronic treatment of naltrexone on hepatic encephalopathy parameters were reversed by L-NAME. Plasma NOx concentrations elevated in BDL rats, which were decreased after acute- and chronic treatment by naltrexone or L-NAME, significantly. We suggest both acute, and chronic treatment with naltrexone improved LPS-induced HE. But, only acute treatment with naltrexone may affect through NO pathway.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

HIV-1 and cocaine disrupt dopamine reuptake and medium spiny neurons in female rat striatum.

HIV-1 and addictive drugs, such as cocaine (COC), may act in combination to produce serious neurological complications. In the present experiments, striatal brain slices from HIV-1 transgenic (Tg) and F344 control female rats were studied. First, we examined dopamine (DA) reuptake in control, HIV-1, COC-treated (5µM) and HIV-1+COC-treated, striatal slices using fast scan cyclic voltammetry. COC-treated striatal slices from F344 control animals significantly increased DA reuptake time (T80), relative to untreated control slices. In contrast, in HIV-1 Tg striatal slices, DA reuptake time was extended by HIV-1, which was not further altered by COC treatment. Second, analysis of medium spiny neuronal populations from striatal brain slices found that controls treated with cocaine displayed increases in spine length, whereas cocaine treated HIV-1 slices displayed decreased spine length. Taken together, the current study provides evidence for dysfunction of the dopamine transporter (DAT) in mediating DA reuptake in HIV-1 Tg rats and limited responses to acute COC exposure. Collectively, dysfunction of the DAT reuptake and altered dendritic spine morphology of the MSNs, suggest a functional disruption of the dopamine system within the HIV-1 Tg rat