Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia; email@example.com
Overcrowding at rats is a model of psychosocial stress. In previous studies we have observed that chronic overcrowding at rats enhanced anxiety, declined immune status and changed noradrenaline and dopamine levels in septum and hypothalamus (Knyazeva et al., 2012; Loseva et al., 2013). In present study we investigated c-fos expression by immunohistochemical method in the brain of rats housed in overcrowded conditions (16 animals per cage) during 15 days. The frontal slices of rat brain at three levels (AP = +4.68 mm; +0.96 mm; -2.52 mm; Paxinos, Watson, 2005) were investigated. The square (in pixels and percent), intensity of fluorescent (in points) and the part of fluorescent cells in the analyzed structures (in the percents) were assessed in different brain structures by our method.
We have observed the increase of the square and/or fluorescent intensity in the brain of overcrowded rats compared with control rats in the following structures: secondary motor cortex (AP=+4.68 mm; -2.52 mm; p<0.1-0.01), primary motor cortex (AP= -2.52 mm; p<0.05), retrosplenial dysgranular cortex (AP= -2.52 mm; p<0.001), cell bridges of the ventral striatum (AP= +0.96 mm; p<0.1) and lateral septal nucleus, ventral part (AP= +0.96 mm; p<0.05).
In addition it has been found the decrease of the square and/or fluorescent intensity in the brain of overcrowded rats compared with control rats in the following structures: islands of Calleja, olfactory tubercle, layer 3, ventral pallidum, substantia innominate, accumbens nucleus, lateral accumbens, cell bridges of the ventral striatum (only square of fluorescent area), lateral septal nucleus (dorsal part), nucleus of the vertical limb of the diagonal band and caudate putamen (AP= +0.96 mm; p<0.1-0.01); and secondary somatosensory cortex, insular cortex (granular, disgranular and agranular), dorsal endopiriform nucleus, posterolateral cortical amygdaloid nucleus (layer 1 and 2), anterior cortical amygdaloid nucleus, medial amygdaloid nucleus, basomedial amygdaloid nucleus, basolateral amygdaloid nucleus, bed nucleus of the stria terminalis (intraamygdaloid division), central amygdaloid nucleus (medial and lateral divisions, and capsular part), commissural stria terminalis, ventromedial hypothalamic nucleus, perifornical part of lateral hypothalamus, fornix, tuberal region of lateral hypothalamus and peduncular part of lateral hypothalamus, mediodorsal thalamic nucleus, reuniens thalamic nucleus, and field CA3 of the hippocampus (AP= -2.52 mm; p<0.05-0.001).
It is assumed that received changes in c-fos expression are an index of functional activity of these brain structures under overcrowded conditions at rats.
The study was partly supported by grant RFH 07-06-00282a