The role of calcium channel blockers and resveratrol in the prevention of paraquat-induced parkinsonism in Drosophila melanogaster: a locomotor analysis

Studies have suggested that neuronal loss in Parkinson's disease (PD) could be related to the pacemaker activity of the substantia nigra pars compacta generated by L-type Ca(v) 1.3 calcium channels, which progressively substitute voltage-dependent sodium channels in this region during aging. Besides this mechanism, which leads to increases in intracellular calcium, other factors are also known to play a role in dopaminergic cell death due to overproduction of reactive oxygen species. Thus, dihydropyridines, a class of calcium channel blockers, and resveratrol, a polyphenol that presents antioxidant properties, may represent therapeutic alternatives for the prevention of PD. In the present study, we tested the effects of the dihydropyridines, isradipine, nifedipine, and nimodipine and of resveratrol upon locomotor behavior in Drosophila melanogaster. As previously described, paraquat induced parkinsonian-like motor deficits. Moreover, none of the drugs tested were able to prevent the motor deficits produced by paraquat. Additionally, isradipine, nifedipine, resveratrol, and ethanol (vehicle), when used in isolation, induced motor deficits in flies. This study is the first demonstration that dyhidropyridines and resveratrol are unable to reverse the locomotor impairments induced by paraquat in Drosophila melanogaster.     

Experimental Post-traumatic Stress Disorder Decreases Astrocyte Density and Changes Astrocytic Polarity in the CA1 Hippocampus of Male Rats

Post-traumatic stress disorder (PTSD) is a psychiatric condition resulting from exposure to a traumatic event. It is characterized by several debilitating symptoms including re-experiencing the past trauma, avoidance behavior, increased fear, and hyperarousal. Key roles in the neuropathology of PTSD and its symptomatology have been attributed to the hippocampus and amygdala. These regions are involved in explicit memory processes and context encoding during fear conditioning. The aim of our study was to investigate whether PTSD is capable of altering the morphology, density and expression of glial fibrillary acidic protein (GFAP) in astrocytes from the CA1 region of the hippocampus and the medial amygdala and correlate the data obtained with the orientation index of the polarity of astrocytes. Thirty male rats were divided in two groups: control (n = 15) and PTSD (n = 15). The inescapable shock protocol, in which the animals are exposed to a single episode of footshock, was used to induce PTSD. Our results show that, in the hippocampus, PTSD is capable of decreasing the density of GFAP+ astrocytes as well as altering astrocytic morphology, as shown by the reductions observed in the total number of primary processes, in the number of primary processes in the lateral quadrants, and the degree of branching in the lateral quadrants. The analysis of the orientation index indicates that PTSD alters the polarity of hippocampal astrocytes. No alterations were observed in the amygdala astrocytes. Therefore, this study demonstrates notable changes in hippocampal astrocytes, supporting the concept that these cells play an important role in PTSD symptomatology.

     

NADPH-diaphorase activity in the nociceptive pathways of land snail Megalobulimus abbreviatus: the involvement of pedal ganglia

NADPH-diaphorase (NADPH-d) is a histochemical marker for nitric oxide synthase (NOS), widely used to identify nitric oxide (NO) producing cells in the nervous system of both vertebrates and invertebrates. Using NADPH-d histochemistry and semi-quantitative optical densitometry, we characterized the NO-producing neurons in the pedal ganglia of young and adult Megalobulimus abbreviatus, subjected to aversive thermal stimulus. The animals were killed at different times (3, 6, 12 and 24 h) following stimulus. The enzymatic activity was detected in different cellular subsets and neuronal processes. In all the studied pedal ganglia subregions, the optical density of positive neurons (P < 0.05) and neuropilar area 1 (P < 0.01) was significantly different in treated animals when compared to controls. The increase in nitrergic activity induced by nociceptive stimulus suggests the involvement of NO in the nociceptive circuit of M. abbreviatus, which is well maintained throughout evolution, and could be helpful in drawing cellular homologies with other gastropods.