title: Gender distinction in neural discrimination of sex pheromones in the olfactory bulb of crucian carp, Carassius carassius.
abstract: Studies on projection of the sensory neurons onto the olfactory bulb in fish have revealed a clear subdivision into spatially different areas that each responded specifically to different classes of odorants. Amino acids induce activity in the lateral part, bile salts induce activity in the medial part, and alarm substances induce activity in the posterior part of the medial olfactory bulb. In the present study, we demonstrate a new feature of the bulbar chemotopy showing that neurons specifically sensitive to sex pheromones are located in a central part of the ventral olfactory bulb in crucian carp. Extensive single-unit recordings were made from these neurons, stimulating with four sex pheromones, 17,20beta-dihydroxy-4-pregnen-3-one, 17,20beta-dihydroxy-4-pregnen-3-one-20-sulfate, androstenedione, and prostaglandin F(2alpha), known to induce specific reproductive behaviors in males of carp fish. All substances were applied separately to the sensory epithelium at a concentration of 10(-9) M. Of the 297 neurons recorded in males, the majority (236 or 79.5%) responded exclusively to one of the four sex pheromones and thus showed a high specificity. Of the 96 neurons recorded from the olfactory bulb in females, only 1 unit showed such a specific activation. These findings reflect remarkable differences between males and females in the discriminatory power of the olfactory neurons toward these sex pheromones. The gender differences are discussed in relation to behavior studies, expression of olfactory receptors, and the convergence of sensory neurons onto the secondary neurons in the olfactory bulb.
authors.affiliation: Department of Molecular Biosciences, University of Oslo, PO Box 1041, Blindern, 0316 Oslo, Norway.
authors.forename: Stine
authors.initials: S
authors.lastname: Lastein
authors.forename: El Hassan
authors.initials: el H
authors.lastname: Hamdani
authors.forename: Kjell B
authors.initials: KB
authors.lastname: Døving
mesh_terms: D000735:Androstenedione / Q000494:pharmacology; D000818:Animals; D002347:Carps; D015237:Dinoprost / Q000494:pharmacology; D004192:Discrimination, Psychological / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006908:Hydroxyprogesterones / Q000494:pharmacology; D008297:Male; D009830:Olfactory Bulb / Q000187:drug effects / Q000502:physiology; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000502:physiology; D012098:Reproduction / Q000187:drug effects / Q000502:physiology; D012724:Sex Attractants / Q000494:pharmacology*; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000187:drug effects* / Q000502:physiology
chemical_list: D006908:Hydroxyprogesterones; D012724:Sex Attractants; C007433:17,20-dihydroxy-4-pregnen-3-one; D000735:Androstenedione; D015237:Dinoprost