Abtract: Ivan Manzini

Sulfated Steroids are Chemosensory Stimuli in Both the Main and Accessory Olfactory System of an Amphibian

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Ivan Manzini (1, 2), Alfredo Sansone (1), Thomas Hassenklöver (1 ,2)

(1) University of Göttingen, Institute of Neurophysiology and Cellular Biophysics, 37073 Göttingen, Germany
(2) University of Göttingen, Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany

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Sulfated steroids are negatively charged molecules with low molecular weight and low volatility that have been shown to be present in mouse urine. They trigger responses in a large number of sensory neurons in the mouse vomeronasal organ, where they may act as pheromones. Using functional calcium imaging in acute slices of the olfactory organ and the olfactory bulb, we found that some pregnanolone-derived (P-mix) and oestrogen-derived (E-mix) sulfated steroids elicit large Ca2+ responses in sensory neurons of Xenopus laevis. Surprisingly, these compounds activate sensory neurons in both the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). However, pregnanolone- and oestrogen-derived steroids showed a differential specificity in the two olfactory organs. Pregnanolone-derived steroids activated sensory neurons in both the MOE and VNO, oestrogen-derived steroids only activated neurons of the MOE. Individual sensory neurons in both organs generally responded to only one of the two steroid mixtures (P-mix or E-mix). Nonetheless, most individual sensory neurons responded to more than one steroid within a mixture, indicating that individual neurons are tuned to detect the class of sulfated steroids (either P-mix or E-mix), rather than single steroids within the same class. Our data support the view that steroid metabolites could be ancestral vertebrate chemosensory stimuli, and provide the basis for further investigations of their physiological role in amphibians.


[Supported by DFG Schwerpunktprogramm 1392 (I.M) and Cluster of Excellence and DFG Research Center Nanoscale Microscopy and Molecular Physiology of the Brain (I.M).]