The peacefulness gene promotes aggression in Drosophila.

Natural aggressiveness is commonly observed in all animal species, and is displayed frequently when animals compete for food, territory and mating. Aggression is an innate behaviour, and is influenced by both environmental and genetic factors. However, the genetics of aggression remains largely unclear. In this study, we identify the peacefulness (pfs) gene as a novel player in the control of male-male aggression in Drosophila. Mutations in pfs decreased intermale aggressiveness, but did not affect locomotor activity, olfactory avoidance response and sexual behaviours. pfs encodes for the evolutionarily conserved molybdenum cofactor (MoCo) synthesis 1 protein (Mocs1), which catalyzes the first step in the MoCo biosynthesis pathway. Neuronal-specific knockdown of pfs decreased aggressiveness. By contrast, overexpression of pfs greatly increased aggressiveness. Knocking down Cinnamon (Cin) catalyzing the final step in the MoCo synthesis pathway, caused a pfs-like aggression phenotype. In humans, inhibition of MoCo-dependent enzymes displays anti-aggressive effects. Thus, the control of aggression by Pfs-dependent MoCo pathways may be conserved throughout evolution.

Aggression and social experience: genetic analysis of visual circuit activity in the control of aggressiveness in Drosophila.

BACKGROUND: Animal aggressiveness is controlled by genetic and environmental factors. Among environmental factors, social experience plays an important role in modulating aggression in vertebrates and invertebrates. In Drosophila, pheromonal activation of olfactory neurons contributes to social suppression of aggression. While it was reported that impairment in vision decreases the level of aggression in Drosophila, it remains unknown if visual perception also contributes to the modulation of aggression by social experience. RESULTS: In this study, we investigate the role of visual perception in the control of aggression in Drosophila. We took several genetic approaches to examine the effects of blocking visual circuit activity on fly aggressive behaviors. In wild type, group housing greatly suppresses aggressiveness. Loss of vision by mutating the ninaB gene does not affect social suppression of fly aggression. Similar suppression of aggressiveness by group housing is observed in fly mutants carrying a mutation in the eya gene leading to complete loss of eye. Chronic visual loss does not affect the level of aggressiveness of single-housed flies that lack social experience prior to behavioral tests. When visual circuit activity is acutely blocked during behavioral test, however, single-housed flies display higher levels of aggressiveness than that of control flies. CONCLUSION: Visual perception does not play a major role in social suppression of aggression in Drosophila. For single-housed individuals lacking social experience prior to behavioral tests, visual perception decreases the level of aggressiveness.

Reduction of hippocampal apoptosis by intracerebroventricular administration of extracellular signal-regulated protein kinase and/or p38 inhibitors in amyloid beta rat model of Alzheimer's disease: involvement of nuclear-related factor-2 and nuclear factor-κB.

In the present study, we examined the effects of intracerebroventricular administration of extracellular signal-regulated protein kinase- (ERK) and p38-specific inhibitors, U0126 and PD169316, respectively, on apoptosis induced by amyloid beta (Aß) in rats. To investigate the effects of these compounds, we evaluated intracellular signalling pathways of apoptosis, as well as inflammatory and antioxidant pathways, 7 and 20 days after Aß injection. We found that caspase-3 and Bax/Bcl-2 ratio, two hallmarks of apoptosis, were significantly decreased in the rats pre-treated with U0126 and PD169316, 7 days after Aß injection. This observation was in agreement with the results of immunostaining analysis of the hippocampus that showed decreased levels of terminal transferase dUTP nick end labelling positive cells in the hippocampus of U0126 and PD169316 pre-treated rats, compared with the Aß-injected group. We also chased the changes in the levels of calpain-2 and caspase-12, two ER factors, in the Aß-injected and treatment groups. Decreased levels of calpain-2 and caspase-12 in U0126 and PD169316 pre-treated rats confirmed the protective effects of these inhibitors. Furthermore, we studied the effect of two stress-sensing transcription factors, nuclear-related factor-2 (Nrf2) and nuclear factor-кB (NF-кB), in Aß-injected as wells as U0126 and PD169316 pre-treated rats. U0126 and PD169316 activated Nrf2 and suppressed NF-кB pathways, 7 days after Aß injection. These antioxidant and inflammatory pathways restored to the vehicle level within 20 days. Taken together, our findings reinforce and extend the notion of the potential neuroprotective role of ERK and/or p38 inhibitors against the neuronal toxicity induced by Aß.

ERK and p38 inhibitors attenuate memory deficits and increase CREB phosphorylation and PGC-1α levels in Aß-injected rats.

In this study, we investigated the effect of intracerebroventricular administration of ERK and p38 specific inhibitors, U0126 and PD169316, respectively, on learning and memory deficits induced by amyloid beta (Aß) in rats. To investigate the effects of these compounds on learning and memory, we performed Morris water maze (MWM) test. U0126 and/or PD169316 improved spatial learning in MWM in Aß-injected rats, 20 days after Aß-injection. To determine the mechanisms of action of U0126 and PD169316, we studies their effect on some intracellular signaling pathways such as Ca(+)/cAMP-response element binding protein (CREB), c-fos, and transcription factors that regulate mitochondrial biogenesis. Based on our data, CREB and c-fos levels decreased 7 days after Aß-injection, while U0126 and/or PD169316 pretreatments significantly increased these levels. Moreover, U0126 and PD169316 activated peroxisome proliferator-activated receptor gamma coactivator-1a, nuclear respiratory factor 1, and mitochondrial transcription factor A, 7 days after Aß-injection. Surprisingly, these factors were returned to vehicle level, 20 days after Aß-injection. Our findings reinforce the potential neuroprotective effect of these inhibitors against the Aß toxicity.

Inhibition of PKA attenuates memory deficits induced by ß-amyloid (1-42), and decreases oxidative stress and NF-κB transcription factors.

Alzheimer's disease (AD), the most relevant cause of dementia in elderly, is characterized by amyloid ß (Aß) containing plaques and neurofibrillatory tangles, synaptic and neuronal loss, along with progressive cognitive impairment in short-term memory. However, mechanistic links between protein kinase A (PKA), oxidative stress and memory loss in response to Aß remain elusive. In the present study, we examined the effects of post-training bilateral intra-hippocampal infusions of the specific protein kinase AII inhibitor, H-89, on memory deficits induced by Aß (1-42) in Aß-pretreated rats. H-89 and Aß were administered immediately after completion of training. All animals were trained for 4 consecutive days and tested 9 and 19 days after the infusions. Significant differences were observed in the time and distance of finding the hidden platform in Aß treated animals after 19 days. Interestingly, intra-hippocampal infusion of H-89 (5µM/side) significantly prevented the Aß-induced memory impairment. Furthermore, evaluation of NFκB (nuclear factor-κB), and antioxidant enzymes, such as γ-GCS (glutamylcysteine synthetase), HO-1 (hemeoxygenase-1), GSH (glutathione), and SOD (superoxide dismutase) confirmed the protective effect of H-89. Given the possible neuroprotective effects of H-89 on Aß-induced memory impairment, our results may open a new avenue for the prevention of AD by PKAII signaling pathway inhibitor.

Changes in phosphorylation of CREB, ERK, and c-fos induction in rat ventral tegmental area, hippocampus and prefrontal cortex after conditioned place preference induced by chemical stimulation of lateral hypothalamus.

Experimental evidence indicates that chemical stimulation of lateral hypothalamus (LH) by carbachol can produce conditioned place preference (CPP) in rats. Several lines of evidence have shown that cAMP-response element binding protein (CREB), extracellular signal-regulated kinase (ERK), and c-fos have pivotal role in CPP induced by drugs of abuse, such as morphine, cocaine, nicotine, and alcohol. Therefore, in the present study, we investigated the changes in phosphorylated-CREB (p-CREB) and -ERK (p-ERK), and c-fos induction within ventral tegmental area (VTA), hippocampus and prefrontal cortex (PFC) after the acquisition of CPP induced by intra-LH administration of carbachol. Animals were unilaterally implanted by cannula into LH. For chemical stimulation of LH, carbachol (250 nmol/0.5 µl saline) was microinjected once each day, during 3-day conditioning phase (acquisition period) of CPP paradigm. After the acquisition period, the brains were removed, and p-CREB and p-ERK, and c-fos induction in the ipsilateral VTA, hippocampus and PFC were measured by Western blot analysis. The results indicated a significant increase in level of phosphorylated CREB (P<0.01) in VTA, and PFC (P<0.05), during LH stimulation-induced CPP, while its level decreased in hippocampus (P<0.05). Also, in aforementioned regions, an increase in c-fos level was observed, but this enhancement in PFC was not significant. Moreover, p-ERK changed in these areas, but not significantly. Our findings suggest that studying the intracellular signals and their changes, such as phosphorylated-CREB, can elucidate a functional relationship between LH and other brain structures involved in reward processing in rats.

Inhibition of JNK phosphorylation reverses memory deficit induced by ß-amyloid (1-42) associated with decrease of apoptotic factors.

Alzheimer's disease (AD) is the most common form of dementia that is degenerative and terminal disease. The main reason of the disease is still unknown. ß-amyloid (Aß) plaques are the important hallmarks of memory impairment in patients suffering from AD. Aggregation of these plaques in the hippocampus appears during the development of the disease. One of the prominent factors having crucial impact in this process is MAPK. JNK, as a member of MAPK family has a pivotal role, especially in cell survival. We hypothesized that JNK may have beneficial effect on the process of memory improvement. Hence, we performed Morris water maze to investigate the possible impact of JNK inhibitor on spatial memory in Aß-injected rats. Our data indicated that intracerebroventricular administration of SP600125, a JNK inhibitor, could significantly decrease escape latency and increase time spent in target quadrant, in treatment group. Furthermore, we evaluated some of the apoptotic factors in the hippocampus of the treated rats. Based on our data, the inhibitor led to the significant decrease in the amount of caspase-3, TUNEL positive cells, cyclooxygenase-2 and increase in Bcl-2/Bax ratio. Given the possible neuroprotective effects of SP600125 on Aß-induced memory impairment and apoptosis, our results may open a new avenue for the treatment of AD.

Inhibition of LPS-induced apoptosis in differentiated-PC12 cells by new triazine derivatives through NF-κB-mediated suppression of COX-2.

Anti-inflammatory therapy approaches have been in the focus of attention in the treatment of neurodegenerative diseases, such as Alzheimer's disease (AD). In this study, we examined the role of new 1,2,4-triazine derivatives against cytotoxicity exerted by lipopolysaccharide (LPS) in differentiated rat pheochromocytoma (PC12) cell line. Our results indicated that LPS-induced cell death can be inhibited in the presence of some of these compounds, as measured by MTT test, acridine orange/ethidium bromide staining and caspase-3 expression assay. We further showed that these compounds exert their protective effects through the inhibition of LPS-induced generation of nitric oxide and reactive oxygen species. Triazine derivatives inhibited LPS-induced nuclear translocation of nuclear factor- κB, a known regulator of a host of genes involved in specific stress and inflammatory responses. Pretreatment of PC12 cells with triazine derivatives also suppressed LPS-induced cyclooxygenase-2 expression while up-regulated heat shock protein-70 (Hsp-70). Moreover, the treatment of brain diseases is limited by the insufficiency in delivering therapeutic drugs into brain relating to highly limited transport of compounds through blood-brain barrier (BBB). Using a reliable model based on the artificial neural network, we indicated that these compounds are capable of penetrating BBB and may be useful agents for preventing neuroinflammatory diseases like AD.