Fundamental differences in patterns of retinal ageing between primates and mice

Photoreceptors have high metabolic demands and age rapidly, undermining visual function. We base our understanding mainly on ageing mice where elevated inflammation, extracellular deposition, including that of amyloid beta, and rod and cone photoreceptor loss occur, but cones are not lost in ageing primate although their function declines, revealing that primate and mouse age differently. We examine ageing primate retinae and show elevated stress but low inflammation. However, aged primates have a >70% reduction in adenosine triphosphate (ATP) and a decrease in cytochrome c oxidase. There is a shift in cone mitochondrial positioning and glycolytic activity increases. Bruch’s membrane thickens but unlike in mice, amyloid beta is absent. Hence, reduced ATP may explain cone functional decline in ageing but their retained presence offers the possibility of functional restoration if they can be fuelled appropriately to restore cellular function. This is important because as humans we largely depend on cone function to see and are rarely fully dark adapted. Presence of limited aged inflammation and amyloid beta deposition question some of the therapeutic approaches taken to resolve problems of retinal ageing in humans and the possible lack of success in clinical trials in macular degeneration that have targeted inflammatory agents

Short-Term Enrichment Makes Male Rats More Attractive, More Defensive and Alters Hypothalamic Neurons

Innate behaviors are shaped by contingencies built during evolutionary history. On the other hand, environmental stimuli play a significant role in shaping behavior. In particular, a short period of environmental enrichment can enhance cognitive behavior, modify effects of stress on learned behaviors and induce brain plasticity. It is unclear if modulation by environment can extend to innate behaviors which are preserved by intense selection pressure. In the present report we investigate this issue by studying effects of relatively short (14-days) environmental enrichment on two prominent innate behaviors in rats, avoidance of predator odors and ability of males to attract mates. We show that enrichment has strong effects on both the innate behaviors: a) enriched males were more avoidant of a predator odor than non-enriched controls, and had a greater rise in corticosterone levels in response to the odor; and b) had higher testosterone levels and were more attractive to females. Additionally, we demonstrate decrease in dendritic length of neurons of ventrolateral nucleus of hypothalamus, important for reproductive mate-choice and increase in the same in dorsomedial nucleus, important for defensive behavior. Thus, behavioral and hormonal observations provide evidence that a short period of environmental manipulation can alter innate behaviors, providing a good example of gene-environment interaction

Subcellular distributions of calcium/calmodulin-stimulated and guanine nucleotide-regulated adenylate cyclase activities in the cerebral cortex

The subcellular distribution of Ca 2+ /calmodulin-stimulated adenylate cyclase activity was studied in comparison with that of guanine nucleotide-stimulated cyclase activity. The distributions of these activities were similar among the crude fractions but differed among the purified subsynaptosomal fractions. The specific activity of Ca 2+ /calmodulin-stimulated cyclase was highest in a light synaptic membrane fraction, which has few, if any, postsynaptic densities, whereas that of guanine nucleotide-stimulated cyclase was highest in a heavier synaptic membrane fraction rich in postsynaptic densities. These results suggest that the Ca 2+ /calmodulin-stimulated cyclase has, at least in part, a different cellular or subcellular location than the guanine nucleotide-stimulated cyclase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45402/1/11064_2004_Article_BF00965018.pd

Metabolismo del oxígeno en las mitocondrias de placenta humana

Due to the high metabolic demands of the placental tissue during gestation, we decide to analyzed the mitochondrial bioenergetic functions in the human term placenta. Different mitochondrial morphological parameters, membrane potential and cardiolipin content were determined by flow cytometry. Oxygen uptake, hydrogen peroxide production and cytochrome P450 content, were also measured. Some apoptotic mitochondrial proteins were also analyzed by western blot. Two isolated mitochondrial fractions were observed: large/heavy and small/light with different functional characteristics. Oxygen uptake showed a respiratory control (RC) of 3.4?±?0.3 for the heavy mitochondria, and 1.1?±?0.4 for light mitochondria, indicating a respiratory dysfunction in the light fraction. Good levels of polarization were detected in the heavy fraction, meanwhile the light population showed a collapsed ??m. Increased levels of cytochrome P450, higher levels of hydrogen peroxide, and low cardiolipin content were described for the light fraction. Three pro-apoptotic proteins p53, Bax, and cytochrome c were found increased in the heavy mitochondrial fraction; and deficient in the light fraction. The heavy mitochondrial fraction showed an improved respiratory function. This mitochondrial fraction, being probably from cytotrophoblast cells showed higher content of proteins able to induce apoptosis, indicating that these cells can effectively execute an apoptotic program in the presence of a death stimulus. Meanwhile the light and small organelles probably from syncytiotrophoblast, with a low oxygen metabolism, low level of ??m, and increased hydrogen peroxide production, may not actively perform an apoptotic process due to their deficient energetic level. This study contributes to the characterization of functional parameters of human placenta mitochondria in order to understand the oxygen metabolism during the physiological process of gestation

Enriched environment reduces stress impairment of spatial working memory in rats

No abstract availabl