Givaudan-Roure Lecture - Association for Chemoreception Sciences

61 Poster [ ] Olfaction: Animal Behavior
NOT ONLY - BUT ALSO -ADRENOCEPTORS ARE INVOLVED
IN EARLY ODOR PREFERENCE LEARNING IN THE RAT
Mclean J.H. 1, Mccann J. 2, Darby-King A. 1, Harley C.W. 2 1Basic
Medical Sciences, Memorial University of Newfoundland, St. John's,
Newfoundland, Canada; 2Psychology, Memorial University of
Newfoundland, St. John's, Newfoundland, Canada
Early preference olfactory learning is important for the survival of
infant rats because they need to associate the odor of the mother with
reward (food). In the neonate, tactile stimulation activates the locus
coeruleus (Nakamura et al., 1987) in the brain stem. Noradrenergic
(NE) neurons in the locus coeruleus (LC) have a strong axonal
projection to the olfactory bulb (Shipley et al., 1985; McLean and
Shipley, 1989; McLean et al., 1991). When NE activation is paired
with odor in the neonate, preference for the odor (learning) takes place
(Sullivan et al., 2000;Sullivan et al., 1991;Sullivan et al., 1989;Price et
al., 1998;Langdon et al., 1997). The LC β-adrenergic input has been
shown to be necessary and sufficient for preference acquisition to occur
in rats up to around postnatal day 10. Surprisingly, despite observations
that α-adrenoceptors are present (Day et al. 1997, Winzer Serhan et al,
1997) and functional (Hayar et al. 2001) in the olfactory bulb, there is
relatively little known about their function in behavior. In this study, we
tested the hypothesis that α-adrenoceptors have roles similar to the βadrenoceptors
in early olfactory learning. In this set of experiments we
showed that activation of the α1-adrenoceptors was sufficient to induce
early preference learning in the rat while the α2-adrenoceptor agonists
did not show an effect. The α-adrenoceptors acted in a dose-dependent
manner similar to the β-adrenoceptors in early odor preference learning.
This work is supported by a grant from CIHR-CEDA Regional
Partnership
62 Poster [ ] Olfaction: Animal Behavior
THE EFFECT OF CONCENTRATION AND CONDITIONING
ON ODORANT DISCRIMINATION BY THE HONEYBEE
Fussnecker B.L. 1, Carlton M. 1, Wright G. 2, Smith B.H. 1 1Entomology,
Ohio State University, Columbus, OH; 2Mathematical Biosciences
Institute, Ohio State University, columbus, OH
Naturally occurring odors used by animals for mate recognition, food
identification and other purposes must be detected at concentrations that
vary across several orders of magnitude. Olfactory systems must
therefore have the capacity to represent odors over a large range of
concentrations regardless of dramatic changes in odor salience. The
stability of the representation of an odor relative to other odors across
concentration has not been extensively evaluated. We tested the ability
of honeybees to discriminate pure odorants across a range of
concentrations at and above their detection threshold. We also
examined how their ability to discriminate among odors changed as a
function of the number of times they had encountered an odorant in
association with an appetitive reward. Our study showed that
discrimination among odorants was a function both of the concentration
and the number of experiences a subject has with an odorant. We
hypothesize that this arises from two separate mechanisms in the
olfactory system.
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63 Poster [ ] Olfaction: Animal Behavior
DILTIAZEM ADMINISTERED NASALLY DECREASES FOOD
INTAKE AND ATTENUATES WEIGHT GAIN IN RATS
Maher T.J. 1, Amer A. 1, Adams C. 2, Chen W. 3, Weinrich K. 3
1Massachusetts College of Pharmacy and Health Sciences, Boston, MA;
2Compellis Pharmaceuticals, Somerville, MA; 3Longwood
Pharmaceuticals, Inc., Boston, MA
Energy intake is continuously influenced by many complex
endogenous neurochemical systems located both centrally and
peripherally, in addition to numerous external environmental stimuli,
such as olfaction. As the processing of odorant information by many
olfactory neurons is mediated via Ca2+-currents through Ca2+
channels, a novel approach at influencing the ingestive behaviors of
animals might therefore involve altering olfactory acuity via Ca2+
channel blockade. The present study tested the ability of a Ca2+
channel blocker, diltiazem (D), to alter food intake in rats made
hyperphagic. D was delivered using the intranasal (i.n.), intraperitoneal
(i.p.) and oral (p.o.) routes of administration. Male Sprague Dawley rats
maintained in a reversed-lighting environment, which had been fooddeprived
for 4hrs at the beginning of the dark cycle, were administered
different doses of D or vehicle (V) and the amount of food consumed
was measured. While food intake at 1, 2 and 4 hrs post D administration
was significantly decreased in a dose-dependent manner after i.n.
administration, neither the i.p. nor p.o. routes significantly affected food
intake. In another experiment, rats were trained to eat their daily meal
during the first 4hrs at the onset of the dark cycle. Once acclimated to
this schedule, daily treatment for 14 days with i.n. D or V prior to food
introduction resulted in a dose-dependent attenuation of weight gain.
Together these studies suggest that i.n. administration of D possesses
significant anorectic activity that may have utility in influencing energy
intake. Additional studies are needed to determine the exact
mechanisms and sites of action of i.n. administered D.
64 Poster [ ] Olfaction: Animal Behavior
KV1.3-TARGETED GENE-DELETION INCREASES
METABOLIC FUNCTION AND OLFACTORY ABILITY
Thompson R.N. 1, Perkins R.M. 1, Parsons A.D. 2, Overton M. 2, Fadool
D. 1 1Dept. Biological Sci, Prog. in Neurosci., Florida State University,
Tallahassee, FL; 2Dept Nutrition, Food, & Exer Sci, Prog. in Neurosci.,
Florida State University, Tallahassee, FL
Mice with gene-targeted deletion (KO) of the voltage-dependent K
channel, Kv1.3, have smaller glomeruli and thus were behaviorally
phenotyped to understand the channel´s contribution to olfaction. Mice
were monitored (8d) in environmental chambers where data are
computer-acquired every 30 seconds. KO animals were found to have
abnormal ingestive behaviors yet equivalent daily caloric/water intake;
KOs ate more intermittently and drank larger volumes less frequently.
KO animals had slightly increased metabolism and locomotor activity
in the dark cycle and weighed less than aged-matched wildtype mice.
KO mice were not anosmic, in fact, retrieval time to recover a hidden
food item was twice as fast as that observed for wildtype mice. Odor
habituation trials using complex mixtures and single alcohols indicated
that KO mice can discriminate molecules differing by only 1 carbon.
Food-restricted mice were trained to dig for a hidden reward paired
with an odorant using a two-choice paradigm to determine odorant
threshold ability. KO mice performed the paired task more quickly and
at concentrations 1,000 to 10,000 fold less than that by wildtype mice.
While these tasks are influenced by memory, both genotypes performed
equivalently in object recognition testing and test of motivation for
object exploration. This unusual set of behaviors in the Kv1.3 KO mice
suggest that Kv1.3 serves additional roles beyond shaping the resting
potential. Supported by NIH DC03387(NIDCD) and NIH HL-56732.