Learned association between context and drug abuse is essential for the drug conditioned place preference （CPP）, which is an animal model widely used to measure drug reward. Synaptic plasticity, in the form of long-...
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Learned association between context and drug abuse is essential for the drug conditioned place preference （CPP）, which is an animal model widely used to measure drug reward. Synaptic plasticity, in the form of long-term potentiation （LTP） and depression （LTD）, is regarded as a proposed cellular substrate of learning and memory. However, the exact role of LTP/LTD in addiction is not known yet. Therefore, by bioinformatics we designed peptides aiming to interfere with LTP and LTD respectively, to study their individual role in the expression of morphine CPP. We found that the interfering peptide Pep-A2 can specifically block hippocampal LTP in CA1 region, whereas Pep-A3 can block LTD in this region. Treatment of either of their cell penetrating forms （Tat-A2 or Tat-A3） before test can block the expression of Morphine CPP in mice. These results suggested that both LTP and LTD are required in the drug-associated learning and memory.
OH-CATH is a novel cathelicidin identified from king cobra. It showed strong antibacterial activity against various bacteria in the presence of 1% NaCl and no haemolytic activity toward human red blood cells even at a...
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OH-CATH is a novel cathelicidin identified from king cobra. It showed strong antibacterial activity against various bacteria in the presence of 1% NaCl and no haemolytic activity toward human red blood cells even at a high concentration. OH-CATH might serve as model molecules for the development of antimicrobial drugs. Understanding the action mechanism of OH-CATH and the reason for its selectivity against microbes is very important for this purpose. The bactericidal effect of the king cobra antimicrobial peptide OH-CATH on Gram-negative Escherichia coli （ATCC 25922） is observed by scanning electron microscopy （SEM） and transmitted electron microscopy （TEM）. The SEM and TEM results suggested that the bactericidal mechanism of OH-CATH against Escherichia coli happened in three steps. Firstly, OH-CATH attached to the negatively charged bacterial wall by positively charged amino acid residues. In the second step, the accumulated OH-CATH aggregated and damaged the bacteria membrane in a pore-forming manner. In the last step, with the damage of cell permeability, the contents of the cells were released and eventually cells died.
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