Structure-activity relationship of a neurite outgrowth-promoting substance purified from the brown alga,Sargassum macrocarpum, and its analogues on PC12D cells

The structure-activity relationship of a neurite outgrowth-promotingsubstance (designated as MC14) from the brown alga, Sargassummacrocarpum, was analysed. Eight synthetic carotenoids and1,4-benzoquinone were used to determine the moiety of the MC14molecule structurally responsible for the nerve growth factor(NGF)-mediated neurite outgrowth-promoting activity on PC12D cells.The bioassays showed that none of these carotenoids exhibitedNGF-potentiating activity. In contrast, 1,4-benzoquinone enhancedsignificantly NGF-mediated neurite outgrowth from PC12D cells, therebeing a 260% increase over the activity of negative control (10 ngmL^-1 NGF). The effect of quinone structure on NGF-potentiatingactivity, when examined using 12 naturally occurring quinones,demonstrated that lawsone, alizarin and lapachol significantly enhancedNGF-mediated neurite outgrowth by 329%, 325% and 265%,respectively, of that in the negative control. These results show thatquinone is the structural moiety of MC14 molecule responsible for theneurite outgrowth-promoting activity. In addition, the hydroxyl groupbonded to quinone had a significant effect on neuritogenic activity. Thebearing of a hydroxyl group at the 1'-position of benzoquinone, and thebearing of two hydroxyl groups at the 1' and 2'-positions of anthraquinone,played a crucial role in enhancing the neurite outgrowth-promoting actionof NGF.     

Nerve growth factor levels in mouse serum: Variations due to stress

The presence of nerve growth factor (NGF) in the serum of adult male mice was assayed using the chick embryo dorsal root ganglion (DRG) bioassay technique in a serum free N1 supplemented medium. Wide variations in the serum-induced nerve fiber outgrowth response were observed when serum was obtained from animals maintained four per cage. Of 64 mice tested, sera of 7 animals induced a profound nerve fiber outgrowth response while the sera of 57 mice failed to show a similar response. In animals kept in isolation for 7 days prior to the start of the experiment, aggression provoked a marked increase in serum NGF levels. In contrast to the sera of aggression-unprovoked mice, the sera of all aggression-provoked mice stimulated a dense nerve fiber outgrowth. The sera of both groups of mice stimulated an intense proliferation and migration of nonneuronal cells. The neurite outgrowth responses elicited by sera from aggression-provoked and unprovoked mice were completely inhibited by the rabbit anti-NGF antiserum. In conclusion, both crowded housing and aggression in mice may provoke an elevation in the serum NGF levels that can be confirmed by the ganglion bioassay technique.     

Characterization of a β-nerve growth factor expression vector for mammalian cells

A mammalian expression vector that directs expression of murine β-nerve growth factor (β-NGF) from a murine sarcoma virus long terminal repeat (LTR) promoter element was constructed and characterized. The vector, designated pLTRSNGF, was stably transfected into murine L-cells, and β-NGF mRNA and protein levels were quantified and compared to endogenous levels in control L-cells. Transfection of pLTRSNGF resulted in an approximate doubling of both β-NGF mRNA and mature β-NGF protein secreted into the media. Transfection of pLTRSNGF into rat PC 12 cells resulted in colonies of autocrine-differentiating cells that extended dense networks of neurites in the absence of added NGF, indicating that the β-NGF produced from the vector is biologically active.