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Effects of individual stressors used in a battery of “chronic unpredictable stress” on long - term plasticity in the hippocampus of juvenile rats

100%

Gorbunova A. A., Kudryashova I. V., Manolova A. O., Novikova M. R., Stepanichev M. Y., Gulyaeva N. V.

Acta Neurobiologiae Experimentalis

2017

tom 77

nr 3

We have studied alterations in the properties of long‑term potentiation (LTP) in hippocampal slices of juvenile rats induced by the exposure of animals to different individual stressors usually used in batteries of chronic unpredictable stress (CUS), a widely used model of depression. Social isolation for 16 h did substantially affect neither the magnitude and nor the development of LTP. The effects of stroboscopic illumination and water deprivation appeared most severe, though opposite: the first stressor had activating effect, whereas the second one inhibited the development of LTP. In addition to the effects of these factors on the LTP magnitude, they also affected the patterns of LTP development. In this study weak tetanization with different probability of maintenance was used, and most of stressors, in spite of the similar LTP magnitude, influenced significantly on the process of consolidation. In hippocampal slices from rats maintained on wet bedding for 16 h, the time course but not magnitude of LTP significantly differed from that observed in the control or socially isolated rats. The weakest effect on LTP was observed in hippocampal slices of the rats exposed to food deprivation. In these animals, only some differences were observed in the development of LTP as compared to socially isolated rats. These data allow ranging stressors used in CUS paradigms according to the severity of their potential effects on neuronal function and animal behavior.

Anhedonia but not passive floating is an indicator of depressive-like behavior in two chronic stress paradigms

84%

Stepanichev M. Y., Tishkina A. O., Novikova M. R., Levshina I. P., Freiman S. V., Onufriev M. V., Levchenko O. A., Lazareva N. A., Gulyaeva N. V.

Acta Neurobiologiae Experimentalis

2016

tom 76

nr 4

Depression is the most common form of mental disability in the world. Depressive episodes may be precipitated by severe acute stressful events or by mild chronic stressors. Studies on the mechanisms of depression require both appropriate experimental models (most of them based on the exposure of animals to chronic stressors), and appropriate tests for assessment of depressive states. In this study male Wistar rats were exposed to two different chronic stress paradigms: an eight‑week chronic unpredictable mild stress or a two‑week combined chronic stress. The behavioral effects of stress were evaluated using sucrose preference, forced swim and open field tests. After the exposure to chronic unpredictable mild stress, anhedonia was developed, activity in the open field increased, while no changes in the duration of passive floating could be detected. After chronic combined stress, anhedonia was also evident, whereas behavior in the open field and forced swim test did not change. The levels of corticosterone in the blood and brain structures involved in stress‑response did not differ from control in both experiments. The absence of significant changes in corticosterone levels and passive floating may be indicative of the adaptation of animals to chronic stress. Anhedonia appears to be a more sensitive indicator of depressive‑like behavioral effects of chronic stress as compared to behavior in the forced swim or open field tests.

Ograniczanie wyników

2 Acta Neurobiologiae Experimentalis

2 Gulyaeva N. V.

2 Novikova M. R.

2 Stepanichev M. Y.

1 Freiman S. V.

1 Gorbunova A. A.

1 Kudryashova I. V.

1 Lazareva N. A.

1 Levchenko O. A.

1 Levshina I. P.

1 Manolova A. O.

1 Onufriev M. V.

1 Tishkina A. O.

1 2017

1 2016

Wyniki wyszukiwania

Effects of individual stressors used in a battery of “chronic unpredictable stress” on long - term plasticity in the hippocampus of juvenile rats

Anhedonia but not passive floating is an indicator of depressive-like behavior in two chronic stress paradigms