Abstracts - Association for Chemoreception Sciences

#P197 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
#P198 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
Interspecies communication mediated by tear fluids
Mai Tsunoda, Kazushige Touhara
Department of Applied Biological chemistry, The University of Tokyo
Tokyo, Japan
Communication between animals are regulated by a variety
of chemical cues emitted from the body fluids. Recent works
have revealed that exocrine grand-secreting peptide 1 (ESP1),
which is released from male mouse tear fluids, enhances female
sexual behavior through the vomeronasal organ. This data
indicates that the tear fluid is one of the important sources of
chemical cues. However, it is unknown whether tear-derived
chemical cues mediate only intraspecies communication. In this
study, we aimed to understand a novel function of tear fluids in
interspecies communication by focusing on tear fluids of rats, a
predator of mice. First, we examined the effect of rat tear fluids
on the mouse vomeronasal system. c-Fos analysis revealed that
rat tear fluids contained some stimulants that induced c-Fos
expression in the accessory olfactory bulb (AOB), the first center
of the vomeronasal system. It has been known that rats have 10
members of ESP family genes, therefore, we examined whether
the stimulants in rat tear fluids are ratESPs. Western blot analysis
indicated that ratESP5 and ratESP7 were secreted in rat tear
fluids. However, recombinant ratESP5 and ratESP7 did not
induce c-Fos expression in the mouse AOB. This data suggests
that there exists novel mouse vomeronasal stimulants in rat tear
fluids. We next purified the stimulants from rat tear fluids by
activity-based fractionation. Amino-terminal peptide sequence
and genome analysis revealed that a c-Fos-inducing peptide
was encoded by a gene whose function has not been revealed.
We named this peptide P18. Recombinent P18 induced c-Fos
expression in the AOB of wild type mice, but not in the TRPC2
knock-out mice. These results suggest a possibility that P18 in
rat tear fluids mediate interspecies communication through the
vomeronasal organ.
Experience-dependent plasticity causes sexual dimorphism
in mouse pheromone-sensing neurons
Pei S. Xu, Timothy E. Holy
Department of Anatomy & Neurobiology, Washington University
School of Medicine St. Louis, MO, USA
In mice, the normal expression of most sex-specific behaviors
requires an intact accessary olfactory system (AOS). While
the AOS has been long viewed as a sexually dimorphic circuit,
the known anatomical differences between males and females
consist of modest changes in the packing of neurons in
particular brain regions. By themselves, these differences may
be insufficient to explain observed dimorphic behaviors. Here
we asked whether the first order neurons, AOS sensory neurons
differed functionally between two sexes. Using light-sheet based
high-speed calcium imaging technique, we recorded ~260,000
individual neurons in intact vomeronasal epithelia from male
and female mice. According to the cell responses to 12 sulfated
steroids, a class of chemicals that originally isolated from mouse
urine, we classified a total of 20, 853 responsive neurons into 17
functional types. We found that the large majority of functional
receptor types present in equal abundance in males and females.
However, we found clear sexual dimorphism, as two functional
types appeared to be male specific, including an epitestosteroneselective
receptor type 100-fold more abundant in males than in
females. To explore the mechanism generating this dimorphism,
we found male specific receptor types became rare after longterm
exposure to the odors of female mice, with the result that
the vomeronasal organs from males were converted to a pattern
indistinguishable from females. This difference in AOS receptor
type is by far the strongest sexual dimorphism ever reported in
the mammalian central nervous system; that this dimorphism is
determined entirely by experience indicates that a sensory system
devoted to “innate” responses is strongly modulated by rearing
conditions. Acknowledgements: This study was funded by NIH-
NINDS/NIAAA Grant R01 NS068409, and NIH Director’s
Pioneer Award DP1 OD006437(T.E.H.)
POSTER PRESENTATIONS
Abstracts are printed as submitted by the author(s).
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