Emotional and cognitive reinforcement of rat hippocampal long-term potentiation by different learning paradigms

In earlier studies we have shown that a protein-synthesis-independent, early, long-term potentiaton (early-LTP) that lasts up to 4-5 hours can be transformed (reinforced) into a protein-synthesis-dependent late-LTP that lasts > or = 8 hours by either an emotional challenge (e.g. swim stress) or mastering a cognitive task (e.g. spatial learning). In the present study we show that LTP-reinforcement by spatial training depends on the specific constraints of the learning paradigm. In a holeboard paradigm,LTP-reinforcement is related to the formation of a lasting reference memory whereas water-maze training gives more heterogenous results. Thus, cognitive aspects interfere with emotionally challenging components of the latter paradigm. These data indicate that different spatial-learning tasks are weighted distinctly by the animal. Thus, we show that aspects of specific spatial learning paradigms such as shifts of attention and emotional content directly influence functional plasticity and memory formation.     

Molecular species of oxidized phospholipids in brain differentiate between learning- and memory impaired and unimpaired aged rats

Amino Acids - Loss of cognitive function is a typical consequence of aging in humans and rodents. The extent of decline in spatial memory performance of rats, assessed by a hole-board test, reaches...     

Housing conditions affect susceptibility to mercury in the golden hamster

Individually-housed and group-housed golden hamsters (Mesocricetus auratus), aged 8 weeks, were studied with regard to their susceptibility to a single gavage of mercuric chloride (10 mg/kg body weight). Body weight and food consumption were measured for 10 days (day -9 to day 0) in a pre-application period and for 13 days (day 1 to day 13) in a post-application period. Mercuric chloride administration significantly reduced body weight gain in both isolated and grouped hamsters at day 1 compared to vehicle controls. While the individually-housed treated hamsters recovered during the post-application period, the group-housed treated hamsters showed a reduced body weight gain over the whole post-application period. Results are discussed in relation to elevated susceptibility to intoxication in group-housed hamsters triggered by high social stress. This study highlights the need to carefully consider the housing conditions which can influence the results of teratological experiments.     

Doublecortin and IGF-1R protein levels are reduced in spite of unchanged DNA methylation in the hippocampus of aged rats

Amino Acids - The aim of the current study was to investigate whether doublecortin (DCX), insulin-like growth factor receptor 1 (IGF-1R) and metabotropic glutamate receptor 5 (mGluR5) levels are...     

High cell density cultivation of Escherichia coli at controlled specific growth rate.

A high cell density cultivation (HCDC) for growth of Escherichia coli in an especially designed glucose/mineral salt medium is proposed. The HCDC essentially starts as a batch process which is followed by a two-phase fed-batch cultivation. After unlimited growth at mu max = 0.45 h-1 in the batch part, growth was controlled at a reduced specific growth rate (mu = 0.11 h-1 less than mu max) over a period of 3 doubling times in which the biomass concentration increased from 12 to 95 g 1(-1) (phase 1 of fed-batch cultivation). Control of growth (mu) was realized by a PO2 control loop (by variation of glucose feeding) and a mu control loop (by variation of agitation speed N) while the actual mu was calculated from the off-gas composition. If the agitation rate cannot be increased anymore the mu controller is switched off (end of phase 1). In the following phase 2, mu declines, however, the still acting pO2 (glucose) controller guarantees sufficient O2 supply till the end of the cultivation with a biomass concentration of 110 g 1(-1) (dry mass). The proposed HCDC suppresses generation of inhibitory by-products and the high yield coefficients indicate the economy of the process.