The signs of depression in ”depressive” and ”non-depressive” rats – Correlation with density of [formula omitted]-receptors in the brain structures

Abstract

Introduction Alterations of the structure of the sleep- wakefulness cycle (SWC) are observed in various psycho-neurological disorders including depression in relationship with dysfunction of the different neurotransmission systems. The signs of the disturbances refer to decrease of REM-sleep onset, increase of intensity and duration of this phase and related mood disorders are caused by depletion of one or more of these neurotransmitters. Although even with the amount of clinical and experimental date the problems of participation of the opioid system in the sense of its importance in the development of depression and regulation of SWC are not still solved. The objective of the present study was to analyze the behavioral parameters and character of the structure of the SWC in the ”depressive” (D) and the ”non-depressive” (ND) rats in correlation of the μ -opioid receptors density in the limbic structures of the brain. Materials and methods Experiments were conducted on the mongrel albino adult rats (n = 10) using the following methods: the Porsolt’s and sucrose (32% liquid) preference tests – for definition of the depressive signs; the stereotaxic – for electrodes implantation; the polisomnographic (Cadwell system) – for registration of the structure of SWC; biochemical investigation of opioid MOR-1 μ – for definition of the receptors density in the various structures of the brain. The obtained results were processed statistically and significance of the changes was determined by the Student t-test. Results The structure of the daily SWC was difference in the D as compared with the ND rats. The fragmentation of the SWC was more noted in D animals (p μ -receptors was elevated in amygdala and nucleus caudatus, in D rat’s compared to ND rats. Conclusion The signs of depressiion – low of motor activity and level of motivation, increasing of the PS duration, fragmentation of the SWC significantly correlate with high density of μ -receptors in the brain structures especially in amygdala in D rats as compared with the ND rats. Acknowledgements The study was supported by GNSF N232 grant.