title: Density of acetylcholine esterase (AchE) and tyrosine hydroxylase (TH) containing fibers in the amygdala of roman high- and low-avoidance rats.
abstract: The cholinergic and dopaminergic innervation of the amygdala plays an important role in attention, emotional arousal, aversive forms of associative learning, conditioned responses, and stress responsivity. Roman High- (RHA) and Low-Avoidance (RLA) rats are an ideal model to study the potential impact of this innervation on behavioral responses, because they were selected bidirectionally for differences in their two-way active avoidance performance. RHA rats are known to quickly acquire two-way active avoidance and show indications of enhanced impulsive behavior, novelty seeking, and vulnerability to substance abuse, whereas RLA rats exhibit a passive coping style with high levels of immobility and enhanced stress responsivity. In the present study, the density of acetylcholine esterase (AchE)-positive cholinergic fibers and tyrosine hydroxylase immunoreactive (TH-ir) fibers were analyzed in various amygdala nuclei. In comparison to RLA rats, RHA rats displayed a significantly higher density of AchE-positive fibers in the lateral nucleus (La), the major sensory input area of the amygdala. In contrast, RLA rats showed a higher density of TH-ir fibers in the lateral division of the central nucleus (CeL), which modulates amygdala output and is known to contain more corticotropin-releasing hormone (CRH) positive neurons in RLA than in RHA rats. The findings suggest that a higher density of AchE-positive fibers in the La of RHA rats may facilitate attentional mechanisms and aversive forms of associative learning in RHA rats, whereas the increased density of TH-ir fibers in the CeL of RLA rats may be involved in the regulation of enhanced CRH expression and stress responsivity.
authors: Institute of Anatomy, Otto von Guericke University Magdeburg, D-39120, Magdeburg, Germany; Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, USA. Electronic address: denizyilmazer-hanke@creighton.edu.
authors: Deniz
authors: D
authors: Yilmazer-Hanke
authors: Institute of Anatomy and Cell Biology, University of Würzburg, D-97070, Würzburg, Germany.
authors: Marina
authors: M
authors: Eliava
authors: Institute of Anatomy, Otto von Guericke University Magdeburg, D-39120, Magdeburg, Germany.
authors: Joachim
authors: J
authors: Hanke
authors: Institute of Anatomy, Otto von Guericke University Magdeburg, D-39120, Magdeburg, Germany.
authors: Herbert
authors: H
authors: Schwegler
authors: Institute of Anatomy and Cell Biology, University of Würzburg, D-97070, Würzburg, Germany.
authors: Esther
authors: E
authors: Asan
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D007175:Impulsive Behavior / Q000502:physiology; D009412:Nerve Fibers / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D003346:Corticotropin-Releasing Hormone; D014446:Tyrosine 3-Monooxygenase; D000110:Acetylcholinesterase
keywords: Amygdaloid nuclei; Attention; Bidirectional selection; Cholinergic; Dopaminergic; Stress