WD Ma

Indiana University Bloomington, Bloomington, IN, United States

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Publications (3)88.15 Total impact

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    ABSTRACT: The prevailing view of the mammalian olfactory system is that odorants are detected only in the nasal olfactory epithelium, whereas pheromones are generally detected in the vomeronasal organ. Here we show that vomeronasal neurons can actually detect both odorants and pheromones. This suggests that in mammals, as in insects, odorous compounds released from plants or other animal species may act as 'semiochemicals' - signalling molecules that elicit stereotyped behaviours that are advantageous to the emitter or to the receiver.
    Nature 08/2001; 412(6843):142. DOI:10.1038/35084137 · 42.35 Impact Factor
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    ABSTRACT: The vomeronasal organ (VNO) is a chemoreceptive organ that is thought to transduce pheromones into electrical responses that regulate sexual, hormonal and reproductive function in mammals. The characteristics of pheromone signal detection by vomeronasal neurons remain unclear. Here we use a mouse VNO slice preparation to show that six putative pheromones evoke excitatory responses in single vomeronasal neurons, leading to action potential generation and elevated calcium entry. The detection threshold for some of these chemicals is remarkably low, near 10(-11) M, placing these neurons among the most sensitive chemodetectors in mammals. Using confocal calcium imaging, we map the epithelial representation of the pheromones to show that each of the ligands activates a unique, nonoverlapping subset of vomeronasal neurons located in apical zones of the epithelium. These neurons show highly selective tuning properties and their tuning curves do not broaden with increasing concentrations of ligand, unlike those of receptor neurons in the main olfactory epithelium. These findings provide a basis for understanding chemical signals that regulate mammalian communication and sexual behaviour.
    Nature 07/2000; 405(6788):792-6. DOI:10.1038/35015572 · 42.35 Impact Factor
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    ABSTRACT: Mature female mice, grouped in the absence of a male stimulus, exhibit a suppressed estrous cycle (the so-called Lee-Boot effect). We have designed a series of experiments to elucidate the involvement of the adrenal gland in this phenomenon. Our initial results indicate that adrenalectomized mice exhibit a regular estrous cycle in either isolated or grouped conditions. A single, intact mouse caged with five adrenalectomized females showed repeated normal cycles. When the urine samples from group-caged intact mice or group-caged adrenalectomized mice were applied to the external nares of singly caged females, estrous cycles were inhibited in the animals receiving urine from the intact mice but not from the adrenalectomized mice. In addition, corticosterone therapy restored the function of estrus suppression in grouped, adrenalectomized mice. We had previously shown that the urinary excretion of several volatile compounds (2-heptanone, trans-5-hepten-2-one, trans-4-hepten-2-one, pentyl acetate, cis-2-penten-1-yl acetate, and 2,5-dimethylpyrazine) was adrenal mediated (Science 1986; 231:722-725). A further testing of these compounds in relation to estrus suppression has now revealed that a mixture of these compounds is effective, but removing 2, 5-dimethylpyrazine from the mixture abolished the biological response. The overall results of this study show conclusively an important role of the adrenal gland and adrenal-mediated urinary metabolites in estrus suppression.
    Biology of Reproduction 01/1999; 59(6):1317-20. DOI:10.1095/biolreprod59.6.1317 · 3.45 Impact Factor