Central administration of l- and d-aspartate attenuates stress behaviors by social isolation and CRF in neonatal chicks

Intracerebroventricular (i.c.v.) administration of l-aspartate (l-Asp) attenuates stress responses in neonatal chicks, but the mechanism has not been clarified. In the present study, three behavioral experiments were carried out under socially isolated stressful conditions exacerbated by the use of corticotrophin-releasing factor (CRF). In Experiment 1, i.c.v. injection of l-Asp attenuated behavioral stress responses (distress vocalization and active wakefulness) in a dose-dependent manner. Furthermore, l-Asp increased time spent standing/sitting motionless with eyes open and sitting motionless with head dropped (sleeping posture) in comparison with the group receiving CRF alone. In Experiment 2, i.c.v. injection of d-Asp dose-dependently decreased the number of distress vocalizations and the amount of time spent in active wakefulness. d-Asp increased the time spent standing/sitting motionless with eyes open compared with the group receiving CRF alone. In Experiment 3, we directly compared the effect of l-Asp with that of d-Asp. Both l- and d-Asp induced sedative effects under an acutely stressful condition. However, l-Asp, but not d-Asp, increased the time spent in a sleeping posture. These results indicate that both l- and d-Asp, when present in the brain, could induce a sedative effect, while the mechanism for hypnosis in neonatal chicks may be different for l-Asp in comparison with d-Asp.     

Barremian–Bedoulian flint humanly transported from the west bank of the Rhône to the Massif-Central Highlands–A diachronic perspective

Petro-archaeology is a powerful tool useful in understanding the origin and management of rocks discovered in prehistoric sites and the complexity of human territories. This research technique has been applied extensively to the Massif Central and its margins, allowing the revaluation of lithic imports from the Rhodanian corridor. Flint derived from Oligocene conglomerates at Rochemaure–Cruas (Ardèche) was a perennial and often preferred source for prehistoric groups inhabiting the Vivarais lowlands and was exported through the Monts d’Ardèche to the Velay highlands (Haute-Loire) during the upper Pleistocene and the Holocene. This modifies the previously drawn litho-spaces occupied by Neanderthals and Modern Humans and questions their land-use strategies in these contrasting natural landscapes.     

β-Carotene conversion products and their effects on adipose tissue

Recent epidemiological data suggest that β-carotene may be protective against metabolic diseases in which adipose tissue plays a key role. Adipose tissue constitutes the major β-carotene storage tissue and its functions have been shown to be modulated in response to β-carotene breakdown products, especially retinal produced after cleavage by β-carotene 15,15′-monooxygenase (BCMO1), and retinoic acid arising from oxidation of retinal. However, the possibility exists that β-carotene in its intact form can also affect adipocyte function. Development of a knock out model and identification of a loss-of-function mutation have pointed out BCMO1 as being probably the sole enzyme responsible for provitamin A conversion into retinal in mammals. The utilisation of BCMO1^−/−mice should provide insights on β-carotene effect on its own in the future. In humans, intervention studies have highlighted the huge interindividual variation of β-carotene conversion efficiency, possibly due to genetic polymorphisms, which might impact on response to β-carotene. This brief review discusses the processes involved in β-carotene conversion and the effect of cleavage products on body fat and adipose tissue function.     

Striatal histone modifications in models of levodopa-induced dyskinesia

Despite recent advances in the treatment of Parkinson disease (PD), levodopa remains the most effective and widely used therapy. A major limitation to the use of levodopa is the development of abnormal involuntary movements, termed levodopa-induced dyskinesia (LDID), following chronic levodopa treatment. Since recent studies have suggested that modifications of chromatin structure may be responsible for many long-lasting changes in brain function, we have examined post-translational modifications of striatal histones in two models of LDID: an acute murine model and a chronic macaque monkey model, both exposed to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In the primate model, which closely resembles human LDID, we observed that chronic levodopa and the appearance of LDID was associated with marked deacetylation of histone H4, hyperacetylation and dephosphorylation of histone H3, and enhancement of the phosphorylation of extracellular signal-regulated kinase (ERK). In the murine model of acutely rather than chronically induced LDID, dopamine depletion and levodopa treatment also induced deacetylation of histone H4 and phosphorylation of ERK, but histone H3 exhibited decreased trimethylation and reduced rather than enhanced acetylation. These data demonstrate striking changes in striatal histones associated with the induction of LDID in both animal models. The pattern of changes observed, as well as the behavioral features, differed in the two models. However, both models exhibit marked deacetylation of histone H4, suggesting that inhibitors of H4 deacetylation may be useful in preventing or reversing LDID.     

Lipolysis stimulated lipoprotein receptor: a novel molecular link between hyperlipidemia, weight gain, and atherosclerosis in mice

The lipolysis-stimulated lipoprotein receptor, LSR, is a multimeric protein complex in the liver that undergoes conformational changes upon binding of free fatty acids, thereby revealing a binding site (s) that recognizes both apoB and apoE. Complete inactivation of the LSR gene is embryonic lethal in mice. Here we show that removal of a single LSR allele (LSR(-/+)) caused statistically significant increases in both plasma triglyceride and cholesterol levels, a 2-fold increase in plasma triglyceride changes during the post-prandial phase, and delayed clearance of lipid emulsions or a high fat meal. The longer postprandial lipoprotein clearance time observed in LSR(-/+) mice was further increased in LSR(-/+) mice lacking functional low density lipoprotein (LDL) receptors. LSR(-/+) mice placed on a Western-type diet displayed higher plasma triglycerides and cholesterol levels, increased triglyceride-rich lipoproteins and LDL, and increased aorta lipid content, as compared with control mice on the same diet. Furthermore, a direct correlation was observed between the hyperlipidemia and weight gain but only in the LSR(-/+) mice. Knockdown of LSR expression by small interfering RNA in mouse Hepa1-6 cells led to decreased internalization of both DiI-labeled cyclohexanedione-LDL and very low density lipoprotein in the presence of oleate. These data led us to conclude that LSR contributes to the physiological clearance of atherogenic triglyceride-rich lipoproteins and LDL. We propose that LSR cooperates with the LDL receptor in the final hepatic processing of apoB-containing lipoproteins and represents a novel therapeutic target for the treatment of hyperlipidemia associated with obesity and atherosclerosis.