1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

321 Poster Chemosensory Molecular Genetics andVNO/PheromoneNORADRENERGIC MODULATION OF SYNAPTICTRANSMISSION FROM MITRAL TO GRANULE CELLS INTHE ACCESSORY OLFACTORY BULBKaba H. 1 , Huang G. 1 , Zhou Y. 1 , Taniguchi M. 1 1 Department ofIntegrative Physiology, Kochi Medical School, Nankoku, Kochi, JapanWe have shown that the mitral to granule cell synapse in theaccessory olfactory bulb (AOB) is critical site for olfactory learning inmice, in which a female forms a memory to the pheromonal signal ofthe male that mates with her. The formation of this memory depends onmating-induced release of noradrenaline (NA) in the AOB. In supportof this, we have also shown in slice preparations that NA gates longtermpotentiation at the mitral to granule cell synapse via the activationof alpha-2 adrenoceptors. Therefore, we investigated the action of NAon synaptic transmission from mitral to granule cells with the use ofwhole-cell patch-clamp recordings. There are five main observations:(1) NA depressed stimulus-evoked excitatory postsynaptic currents(eEPSCs) recorded from granule cells without affecting the decay of thesynaptic currents; (2) NA depressed the high-threshold calcium currentsin mital cells and the effect of NA was mimicked by the alpha-2-adrenoceptor agonist clonidine; (3) in mitral cells treated with pertusistoxin the effect of clonidine on calcium currents was abolished; (4)clonidine failed to affect outward potassium currents in mitral cells; (5)clonidine reduced the frequency of miniature EPSCs recorded fromgranule cells without affecting the amplitude of the events. Takentogether, our results indicate that alpha2-adrenoreceptor activationdepresses glutamate release from mitral cells by a G-protein-mediatedinhibition of calcium channels and a direct modulation of vesicleexocytosis. Supported by grants from JSPS.322 Poster Chemosensory Molecular Genetics andVNO/PheromoneMEDIAL AMYGDALA RESPONSES TO CHEMOSENSORYSTIMULI FROM SAME AND DIFFERENT SPECIES.Samuelsen C. 1 , Blake C. 1 , Case G. 1 , Meredith M. 1 1 Biological Science,Florida State University, Tallahassee, FLIn the medial amygdala of both hamsters and mice, immediate earlygene (IEG= Fos/ FRAs) expression shows a response to pheromonecontaining chemosensory signals originating from both the animal´sown species (conspecific) and other species (heterospecific). In malehamsters, conspecific stimuli, regardless of gender, activate bothanterior and posterior medial amygdala (MeA, MeP). Withheterospecific stimuli, MeA is activated but (dorsal) MeP (MePd)appears to be suppressed. Stimuli conspecific for hamsters includedfemale hamster vaginal fluid and male or female flank-gland secretion.In male mice, initial results suggested the same pattern of response butlater data suggest that responses in MePd to urine stimuli from othermale mice may be less than the response to urine stimuli from femalemice. Others have found a more dramatic difference, with male stimuliproducing no significant response in medial amygdala of other malemice, and have interpreted these results in terms of a reproductiveresponse to female stimuli and a defensive response to male stimuli, andto heterospecific stimuli. The division of the mouse medial amygdalainto putative reproductive and defensive regions may not account for allresponses to pheromone containing chemosignals in mice, or in otherspecies. Ongoing experiments examine amygdala responses in male andfemale mice and hamsters to additional conspecific and heterospecificstimuli likely to evoke defensive responses, to address these questions.In male hamsters and mice, the largely GABAergic intercalated nucleus(ICN) of the amygdala was activated when MeP was suppressed byheterospecific stimuli, suggesting inhibition of MeP by ICN. Supportedby NIDCD grant DC05813.323 Poster Chemosensory Molecular Genetics andVNO/PheromoneVOLATILE MHC ODORTYPESPreti G. 1 , Kwak J. 1 , Curran M. 1 , Wahl J. 2 , Willse A. 2 , Yamazaki K. 1 ,Beauchamp G. 1 1 Monell Chemical Senses Center, Philadelphia, PA;2 Pacific Northwest National Laboratory, Richland, WAMajor histocompatibility complex (MHC) genes influence urinaryodors (odortypes) of mice. That volatile odorants are involved issupported by the observation that odortype identity can be detectedfrom a distance. Furthermore, chemical analyses of urines have revealednumerous volatile odorants that differ in relative abundance betweenmice that differ only in MHC genotypes. In addition, urines from MHCdifferentmice evoke distinct odor-induced activity maps in the mainolfactory bulbs. Recent studies reported that non-volatile MHC class Ipeptides may directly act as MHC-associated signals. These studiesraise the question of whether the behavioral evidence for volatile MHCsignals needs further verification. To accomplish this, we designed aprocedure to collect peptide-free urinary volatiles and we tested thesevolatiles for their ability to mediate chemosensory discrimination ofmice differing only in their MHC genotype. The headspace volatilesfrom urines of C57BL/6 congenic mice (haplotypes H-2b and H-2k)were collected by solid phase microextraction. These volatiles werethen desorbed into a gas chromatograph and the entire chromatographiceluate was collected into a buffer solution. Our results show that micetrained to discriminate between unadulterated urinary signals of thecongenic mice generalize the discrimination, without reward or training,to the buffer solution containing the peptide-free urinary volatiles. Thusvolatile signals, perhaps along with non-volatile ones, mediatebehavioral discriminations of mice of different MHC genotypes. Thiswork is sponsored by DARPA under ARO Contract No. DAAD19-03-1-0109. Opinions, interpretations, conclusions, and recommendationsare those of the authors and are not necessarily endorsed by the UnitedStates Government.324 Poster Chemosensory Molecular Genetics andVNO/PheromoneFETAL ODORTYPES: CONTRIBUTIONS OF MHC ANDBACKGROUND GENETIC VARIATION.Yamazaki K. 1 , Curran M. 1 , Beauchamp G.K. 1 1 Monell Chemical SensesCenter, Philadelphia, PAIt has long been known that individual animals of many species aredistinguished by unique odors. We and others have repeatedlydemonstrated that these genetically determined individual odors, whichwe have called odortypes, are influenced by genes of the majorhistocompatibility complex (MHC). Other genetic loci (collectivelytermed “background” here) are also involved in provisioning individualmice with unique odors. Among these background loci are ones on theX and Y chromosomes and loci coding for major urinary proteins(MUPs). We have recently found that MHC-determined odortypesproduced by fetuses are expressed in the urinary odors of the pregnantfemale and these fetal odortypes remain in the mother´s circulation daysor longer after the pups are born and have been removed from themother. This phenomenon may be related to microchimerism, thefinding that fetal cells remain functional in the mother long after theinfant has been born. In the current studies we asked whether, inaddition to MHC genetic variation, background genes also contribute tothe fetal odortypes. Additionally, we investigated the interactionbetween MHC and background variation on a recently parturientfemale´s odortype. Using our standard Y-maze training paradigm wefound that (1) background genetic differences influence fetal odortypesremaining in the mother and (2) in some cases background genotypeand MHC interact to obscure the independent contributions of each.Individual volatile body odors are thus influenced in complex ways bygenetic variation at several genetic loci. Supported by NSF grant#0112528.81