title: Activation of projective neurons from the nucleus accumbens to ventral pallidum by a learned aversive taste stimulus in rats: a manganese-enhanced magnetic resonance imaging study.
abstract: Conditioned taste aversion (CTA) causes a palatability shift of a taste stimulus (conditioned stimulus, CS) from ingestive to aversive. We previously found that the ventral pallidum (VP) mediates the palatability shift in CTA. Because the VP receives major projections from the nucleus accumbens (NAc), we examined whether the presentation of CS activates the NAc-VP projective neurons after the establishment of CTA, using a manganese-enhanced magnetic resonance imaging technique. Rats were implanted with a guide cannula in the NAc and an intraoral cannula. After the surgery, they received a pairing of 5 mM saccharin solution with an i.p. injection of 0.15 M lithium chloride (CTA group) or saline (sham group). Two days after the conditioning, rats were microinjected with manganese chloride (MnCl2) into the NAc. Thirty minutes later, the rats were presented with saccharin (CTA-CS and sham-CS groups) or water (CTA-DW and sham-DW groups) via the intraoral cannula. Only the CTA-CS group showed a robust aversion to the CS. At 1 and 2 h after the MnCl2 injection, T1-weighted MR images were acquired using an 11.7 T MRI. Imaging analysis showed that significantly more manganese moved toward the VP in the CTA-CS group than in the other groups. These results indicate that the conditioned aversive taste enhanced the activities of the projective NAc-VP neurons and suggest specific involvement of the NAc-VP pathway in the rejection of CS in retrieval of CTA.
authors.affiliation: Division of Behavioral Physiology, Department of Behavioral Sciences, Graduate School of Human Sciences, Osaka University, Osaka 565-0871, Japan. kenken@hus.osaka-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Inui
authors.forename: C
authors.initials: C
authors.lastname: Inui-Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshioka
authors.forename: I
authors.initials: I
authors.lastname: Ohzawa
authors.forename: T
authors.initials: T
authors.lastname: Shimura
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology*; D005917:Globus Pallidus / Q000187:drug effects / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008345:Manganese / Q000378:metabolism; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009714:Nucleus Accumbens / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013649:Taste / Q000502:physiology*
chemical_list: D008345:Manganese