Sex differences in regulatory changes following quinolinic acid-induced striatal lesions

Research Paper5,6,7 trihydroxy flavone armoured neurodegeneration caused by Quinolinic acid induced huntington's like disease in rat striatum - reinstating the level of brain neurotrophins with special reference to cognitive-socio behaviour, biochemical and histopathological aspects

Huntington Disease (HD), a predominant Neurodegenerative Disorder which might be induced by endogenous neurotoxin called Quinolinic Acid (QA), an N-methyl-D aspartate receptor (NMDAR) agonist, the bilaterally intrastriatal administration (200 nm/2 μL of saline) offers rise to the toxic events like neuronal death, neuroinflammation by inflicting excitotoxicity and oxidative stress in the striatum of male Wistar rats by exhibiting the behavioural changes which was accessed by rotarod, open field analysis. In this study, the neuropharmacological effect of Baicalein (BC) against QA induced HD was evaluated. Baicalein (BC), scientifically 5,6,7 trihydroxy flavone present naturally in the edible plants like Scutellaria baicalensis and Oroxylum indicum possess a better neuroprotective effect in the dosage of 10 mg/kg and 30 mg/kg intraperitoneally in the striatum of HD induced rats. This study proved that BC is efficient to revive the level of enzymatic & non-enzymatic antioxidants and mitochondrial complexes by decreasing the number of inflammatory mediators such as MDA, protein carbonyls and Nitric Oxide at the significance of P < 0.01 and restores the amount of BDNF and GDNF thereby preventing the neurophysiological changes which were analysed by haematoxylin & eosin staining. Thus finally, the protective effect of Baicalein displays the up-gradation of psychological and behavioural changes induced by QA.

Effects of the Novel IDO Inhibitor DWG-1036 on the Behavior of Male and Female 3xTg-AD Mice

The kynurenine pathway metabolizes tryptophan into nicotinamide adenine dinucleotide, producing a number of intermediary metabolites, including 3-hydroxy kynurenine and quinolinic acid, which are involved in the neurodegenerative mechanisms that underlie Alzheimer's disease (AD). Indolamine 2,3-dioxygenase (IDO), the first and rate-limiting enzyme of this pathway, is increased in AD, and it has been hypothesized that blocking this enzyme may slow the progression of AD. In this study, we treated male and female 3xTg-AD and wild-type mice with the novel IDO inhibitor DWG-1036 (80 mg/kg) or vehicle (distilled water) from 2 to 6 months of age and then tested them in a battery of behavioral tests that measured spatial learning and memory (Barnes maze), working memory (trace fear conditioning), motor coordination and learning (rotarod), anxiety (elevated plus maze), and depression (tail suspension test). The 3xTg-AD mice treated with DWG-1036 showed better memory in the trace fear conditioning task and significant improvements in learning but poorer spatial memory in the Barnes maze. DWG-1036 treatment also ameliorated the behaviors associated with increased anxiety in the elevated plus maze and depression-like behaviors in the tail suspension test in 3xTg-AD mice. However, the effects of DWG-1036 treatment on the behavioral tasks were variable, and sex differences were apparent. In addition, high doses of DWG-1036 resulted in reduced body weight, particularly in females. Taken together, our results suggest that the kynurenine pathway is a promising target for treating AD, but more work is needed to determine the effective compounds, examine sex differences, and understand the side effects of the compounds.

Sex differences and estrous cycle-variations in the AF64A-induced cholinergic deficit in the rat hippocampus

The influence of gender and stage of the estrous cycle on the levels of acetylcholine, serotonin, and noradrenaline in the hippocampus and on the susceptibility of the cholinergic septo-hippocampal pathway to the neurotoxic effect of ethylcholine aziridinium (AF64A) was investigated in the rat. Levels of acetylcholine and serotonin were consistently higher in female rats during the stage of diestrus and proestrus than in age-matched male rats (p < 0.05). Across the estrous cycle the highest levels of acetylcholine and serotonin, coinciding with the lowest levels of noradrenaline, were measured on proestrus. Eight to 10 days after the bilateral intracerebroventricular injection of a submaximal dose of AF64A (1 nmol/ventricle) the decrease of acetylcholine in hippocampus was larger in females than in male rats. The reduction of acetylcholine was most pronounced in female rats that had received submaximal doses of AF64A on proestrus (42.7 +/- 3.4%), whereas in male rats, the corresponding decrease was 25.9 +/- 5.1% (p < 0.05). At a maximal dose of AF64A (2 nmole/ventricle), the sex-specific or cycle-dependent difference in the cholinotoxicity of AF64A vanished. The dose-dependent loss of acetylcholine was associated with a secondary dose-dependent decrease in the levels of serotonin and noradrenaline, but significant differences between male and female rats or stages of estrous cycle were not apparent. The present data provide evidence that adult female rats in general, and particularly females on proestrus, are more susceptible to the neurotoxic action of submaximal doses of AF64A than age-matched male rats.

Female rats are more sensitive to the locomotor alterations following quinolinic acid-induced striatal lesions: effects of striatal transplants

The effects of sex differences and hormonal factors on the locomotor alterations following intrastriatal injections of quinolinic acid (QA) and the ability of fetal striatal transplants to reverse those effects were examined. Male, female, or ovariectomized female rats received bilateral injections of 150 nmol QA or vehicle into the striatum. Using a multidimensional analysis of spontaneous nocturnal locomotor behavior, a significant increase in locomotion was observed in female but not male or ovariectomized female rats. The increases in activity observed in the lesioned females were attenuated at 6 and 10 weeks following transplantation of rat fetal (E17) striatal tissue into the lesioned striata. Transplanted striatal tissue had no effect on locomotion in male or ovariectomized female rats. Cytochrome oxidase histochemistry revealed that QA produced a marked loss of metabolic activity in regions exhibiting cell loss. Within these areas there was a marked loss of striatal neurons including those reactive for NADPH diaphorase. Despite the sex-related differences in QA-induced locomotion, there were no apparent differences in the extent of striatal pathology or survival of the grafts in any of the groups receiving QA. These experiments demonstrate a sex-dependent dissociation between the behavioral and neurobiological consequences of QA and suggest that sex and hormonal variables play an important role in the locomotor changes following excitotoxic-induced striatal damage.