Detection of volatile and conspecifics odorants in rats exposed to olfactory environmental enrichment

• Grant number: 13/07580-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2013
• End date: June 30, 2014
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Gilberto Fernando Xavier
• Grantee: Priscila Moreira de Souza
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The occurrence of adult neurogenesis has been reported in several higher vertebrate species, including human beings. In mammals, this process occurs in the subventricular zone (SVZ) of the lateral ventricle and in the subgranular zone (SGZ) of the dentate gyrus in the hippocampus. In rodents, adult neurogenesis in the SVZ seems to be related to the maintenance of the number of cells in both the accessory olfactory bulb, mainly related to detection of non-volatile molecules, e.g., pheromones, and the principal olfactory bulb, mainly related to detection of volatile airborne odors. Exposure of rats to several different odors seems to interfere with both adult neurogenesis and behavioral performance in olfactory tasks. The studies ascribing specific functions to these newborn neurons have produced conflicting results. In addition, only a few studies investigated neurogenesis either in the accessory olfactory bulb of in comparisons involving the principal and accessory olfactory bulbs. The present study aimed at evaluating the effects of olfactory environmental enrichment either with odors that preferentially engage the accessory olfactory bulb, e.g., conspecific odors, or with odors that preferentially engage the principal olfactory bulb, e.g., volatile airborne odors, on later performance in olfactory tasks. Hypothetically, preferential stimulation of one of the olfactory systems (either principal or accessory) should increase its sensitivity thus increasing discrimination of type of stimuli it processes, with corresponding increase in neuron proliferation in the corresponding structure. Independent groups of rats subjected to olfactory environmental enrichment with either volatile airborne odors or conspecific pheromones, in addition to a control group without additional stimulation, will be tested in odor threshold detection tasks using these different types of stimuli. Later the brains of these subjects will be analyzed in order to evaluate the occurrence of increase in proliferation either in the principal or in the accessory bulb, or both. (AU)