Anxiety and Hippocampus Volume in the Rat

Abstract

In depressed patients as well as healthy controls, a positive relationship between hippocampal volume and trait anxiety has been reported. This study sought to explore the possible inter-relation between hippocampal volume and trait anxiety further. Magnetic resonance imaging at 7 T was used to measure hippocampal volumes in a rat model of extremes in trait anxiety (experiment 1) and in a Wistar population with normal anxiety-related behavior (experiment 2). In addition to anxiety-related behavior, potentially confounding factors (depression-like, exploratory, and locomotor behavior) were assessed. Experiment 1 globally supported the hypothesis of a positive relationship between hippocampus volume and trait anxiety but did not allow for ruling out possible confounds arising from cosegregation of other behavioral traits. Experiment 2 yielded strong evidence for a negative relationship which was specific for trait anxiety. Thus, the relationship between hippocampal volume and anxiety may be more complex than expected. Interestingly, anxietyrelated behavior in experiment 2 had a stronger influence on hippocampal volume than depression-like behavior. In the light of hippocampal volume loss in anxiety disorder and frequent comorbidity of anxiety and depression, this finding suggests that further research into the relationship between anxiety and hippocampal volume may be critical for understanding hippocampal contributions to normal and pathological behavior. Neuropsychopharmacology (2006) 31, 925-932.

Expression of α-synuclein is increased in the hippocampus of rats with high levels of innate anxiety

“…31 A role for hippocampal formation in anxiety has been demonstrated and suggested by many studies. [59][60][61][62] Accordingly, in the present study, a-synuclein mRNA levels were twice as high in the hippocampus of the anxious LEW rats when compared to SHR rats. This increase in gene expression was accompanied by a corresponding increase in asynuclein protein expression, which showed an elevation of approximately 50% in the hippocampus of LEW rats when compared to SHR rats.…”

Effects of the BDNF Val66Met Polymorphism on Anxiety-Like Behavior Following Nicotine Withdrawal in Mice

“…[49][50][51][52][53] Hippocampal volume can also be correlated with anxiety levels in patients with anxiety disorders, 54 and is associated with successful quit attempts. 55 Of interest, irregular activation in the hippocampus has been associated with affect in smokers during smoking cue presentation.…”

The association of anxiety disorders and obsessive compulsive personality disorder with anorexia nervosa: Evidence from a family study with discussion of nosological and neurodevelopmental implications

“…An area of research we believe to have particular relevance to our findings is the affective neuroscience perspective on motivated behavior, a literature that has strongly implicated dysfunction in neural circuits mediating anxiety and fear learning in a range of pathological anxiety states. Specifically, in both human and animals studies, a wide range of anxiety phenotypes have been linked to overactivity of the amygdala, a key structure mediating innate fear proneness and the acquisition of learned fear, and of the hippocampus, which mediates the organism's defensive adaptation to novelty and plays a critical role in emotional memory 21,[26][27][28] ; dysfunction in frontal systems that regulate amygdala activation by threatening stimuli 29,30 ; altered morphometry in brain areas underlying the regulation of anxiety and fear-related behaviors 29,[31][32][33][34][35] ; and specific genetic variants that moderate the engagement of these circuits by threat stimuli. 36 Accordingly, behavioral manifestations of amygdaloid and hippocampal structures that are hypersensitive, or abnormally modulated-biased attention to novelty and threat, inhibition of appetitive behavior upon confrontation by novel or aversive environments, enhancement of fear learning, and poor retention of fear extinction (see Gray and McNaughton, 21 and Lang et al 22 for background)-may be a heuristic framework for exploring genetic and neurobiological underpinnings of the anxious premorbid temperament and anxiety-related diagnostic features of AN.…”