A hypomorphic vasopressin allele prevents anxiety-related behavior

In this study, microarray analysis, in situ hybridization, quantitative real-time PCR and immunohistochemistry revealed decreased expression of the vasopressin gene (Avp) in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei of adult LAB mice compared to HAB, NAB (normal anxiety-related behavior) and HABxLAB F1 intercross controls, without detecting differences in receptor expression or density. By sequencing the regions 2.5 kbp up- and downstream of the Avp gene locus, we could identify several polymorphic loci, differing between the HAB and LAB lines. In the gene promoter, a deletion of twelve bp Δ(−2180–2191) is particularly likely to contribute to the reduced Avp expression detected in LAB animals under basal conditions. Indeed, allele-specific transcription analysis of F1 animals revealed a hypomorphic LAB-specific Avp allele with a reduced transcription rate by 75% compared to the HAB-specific allele, thus explaining line-specific Avp expression profiles and phenotypic features. Accordingly, intra-PVN Avp mRNA levels were found to correlate with anxiety-related and depression-like behaviors. In addition to this correlative evidence, a significant, though moderate, genotype/phenotype association was demonstrated in 258 male mice of a freely-segregating F2 panel, suggesting a causal contribution of the Avp promoter deletion to anxiety-related behavior

A Hypomorphic Vasopressin Allele Prevents Anxiety-Related Behavior

To investigate neurobiological correlates of trait anxiety, CD1 mice were selectively bred for extremes in anxiety-related behavior, with high (HAB) and low (LAB) anxiety-related behavior mice additionally differing in behavioral tests reflecting depression-like behavior. promoter deletion to anxiety-related behavior. gene promoter explains gene expression differences in association with the observed phenotype, thus further strengthening the concept of the critical involvement of centrally released AVP in trait anxiety

Differential Stress-Induced Neuronal Activation Patterns in Mouse Lines Selectively Bred for High, Normal or Low Anxiety

There is evidence for a disturbed perception and processing of emotional information in pathological anxiety. Using a rat model of trait anxiety generated by selective breeding, we previously revealed differences in challenge-induced neuronal activation in fear/anxiety-related brain areas between high (HAB) and low (LAB) anxiety rats. To confirm whether findings generalize to other species, we used the corresponding HAB/LAB mouse model and investigated c-Fos responses to elevated open arm exposure. Moreover, for the first time we included normal anxiety mice (NAB) for comparison. The results confirm that HAB mice show hyperanxious behavior compared to their LAB counterparts, with NAB mice displaying an intermediate anxiety phenotype. Open arm challenge revealed altered c-Fos response in prefrontal-cortical, limbic and hypothalamic areas in HAB mice as compared to LAB mice, and this was similar to the differences observed previously in the HAB/LAB rat lines. In mice, however, additional differential c-Fos response was observed in subregions of the amygdala, hypothalamus, nucleus accumbens, midbrain and pons. Most of these differences were also seen between HAB and NAB mice, indicating that it is predominately the HAB line showing altered neuronal processing. Hypothalamic hypoactivation detected in LAB versus NAB mice may be associated with their low-anxiety/high-novelty-seeking phenotype. The detection of similarly disturbed activation patterns in a key set of anxiety-related brain areas in two independent models reflecting psychopathological states of trait anxiety confirms the notion that the altered brain activation in HAB animals is indeed characteristic of enhanced (pathological) anxiety, providing information for potential targets of therapeutic intervention

Quantitative analysis of c-Fos immunoreactivity in HAB, NAB and LAB mice under basal conditions and after OA exposure.

<p>Depicted are those areas (septal, hippocampal, amygdalar and hind brain areas) for which the Fischer LSD <i>post hoc</i> test revealed statistically significant differences in OA-stress-induced c-Fos response in HAB, NAB and LAB mice. Each column indicates the mean±SEM number of c-Fos positive cells in a tissue area of 0.01mm² (total c-Fos expression was quantified in the dentate gyrus). Basal groups: n = 5, OA-exposure: HAB: n = 9, NAB: n = 8, LAB: n = 8; *p<0.05, **p<0.01 vs HAB OA-group; # p<0.05, ## p<0.01 vs corresponding basal group; + p<0.05, ++ p<0.01 vs LAB OA-group;</p

Behavioral parameters of HAB, NAB and LAB mice measured in the 5-min exposure to the OA.

<p>(a) Time spent in distal zone, entries into distal zone, total distance traveled. (b) Head-dip behavior. Values are expressed as mean±SEM. HAB: n = 9, NAB: n = 8, LAB: n = 8; * p<0.05, ** p<0.01.</p

Schematic diagram showing the 59 areas in which c-Fos expression was quantified.

<p>Levels are based on the atlas of Franklin and Paxinos (1997). Squares indicate the placement of grids for counting of c-Fos positive cells. Asterisks indicate the regions in which HAB mice showed changes in OA-induced c-Fos expression as compared to LABs. AcB, nucleus (n.) accumbens; AcBc, n. accumbens core; AcBsh, n. accumbens shell; ACo, anterior cortical n. of the amygdala; AD, anterodorsal thalamic n.; AH, anterior hypothalamic area; Arc, arcuate hypothalamic nucleus; BlA, basolateral n. of the amygdala; BNST, bed n. of the stria terminalis; CA1, CA1 field of the hippocampus; CA3, CA3 field of the hippocampus; CeA, central n. of the amygdala; Cg 1, cingulate ctx (area1); Cg 2, cingulate ctx (area2); Cl, Claustrum; CPu, caudate putamen; cPAGdl, caudal dorsolateral periaqueductal gray; cPAGdm, caudal dorsomedial periaqueductal gray; cPAGl, caudal lateral periaqueductal gray; cPAGvl, caudal ventrolateral periaqueductal gray; DEn, Endopiriform ctx, dorsal; DG, dentate gyrus; DMH, dorsomedial hypothalamic n.; DP, dorsal peduncular nucleus; DR, dorsal raphe n.; GI, granular insular ctx; IL, infralimbic ctx; LA, lateral n. of the amygdala; LC, locus coeruleus; LGP, lateral globus pallidus; LH, lateral hypothalamic area; LHb, lateral habenular n.; LPB, lateral parabrachial n.; LSD, lateral septal n. (dorsal); LSI, lateral septal n. (intermediate); LSV, lateral septal n. (ventral); M1, primary motor ctx; M2, secondary motor ctx; MeA, medial amygdala; MGP, medial globus pallidus; MO, medial orbital cortex; MPA, medial preoptic area; MPO, medial preoptic n.; MPB, medial parabrachial n.; PE, periventricular n; Pir, piriform ctx; PLCo, posterolateral cortical n. of the amygdala; PrL, prelimbic ctx; PV, paraventricular thalamic n.; PVA, paraventricular thalamic n. (anterior); PVN, paraventricular hypothalamic n.; rPAGdl, rostral dorsolateral periaqueductal gray; rPAGdm, rostral dorsomedial periaqueductal gray; rPAGl, rostral lateral periaqueductal gray; RSA, retrosplenial agranular ctx; RSG, retrosplenial granular ctx; S1J, primary somatosensory cortex, jaw region; VMH, ventromedial hypothalamic n.</p

Overview of c-Fos expression following open arm (OA) exposure in HAB, NAB and LAB mice.

<p>Values are numbers of c-Fos positive cells/0.01 mm². (total number of c-Fos positive cells was quantified in the CA1 and CA3 region and the dentate gyrus of the hippocampus). 2-way ANOVA analysis results for <i>line x stress</i> interaction are given in the right column (brain areas showing significant interaction are shown in bold). 2-way ANOVA analysis results for the factor <i>stress</i> are indicated by # P<0.05, ## P<0.01 basal versus OA stress groups; basal groups: n = 5, OA-groups: n = 8–9;</p

Representative microphotographs of c-Fos immunoreactivity in the amygdala.

<p>(a) Schematic diagram, based on the atlas of Franklin and Paxinos (1997), showing the amygdala at the level of −1.46 (Bregma). The square indicates the placement of grids for counting of c-Fos-positive cells in the medial nucleus of the amygdala (MeA). (b) Low magnification overview of the amygdala (−1.46) of a HAB mouse under basal conditions; Scale bar = 500 µm; (c) High magnification, bright field photomicrographs of representative sections matched for comparable rostrocaudal levels showing the distribution of c-Fos expression within the medial nucleus of the amygdala in HAB, NAB and LAB mice under basal conditions and after OA exposure. Scale bar = 100 µm;</p

Correlation analysis of <i>distal arm entries</i> and <i>c-Fos responses</i> in brain areas where HAB, NAB and LAB mice showed significant differences in OA stress-induced c-Fos response.

<p>R and P values revealed by the Spearman test are presented for each brain region.</p