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Published on: December 28, 2011
Time course of alterations after olfactory bulbectomy in mice
Carla Mucignat-Caretta1, Michela Bondí, Antonio Caretta
1Department of Human Anatomy and Physiology, University of Padova, Via Marzolo 3, I-35131 Padova, Italy. carla.mucignat@unipd.it
Abstract:
Olfactory bulbectomy in rodents causes behavioral alterations, which result in a model of depression, validated for pharmacological screening of antidepressant drugs. To unravel the appearance and time course of the major behavioral effects which follow surgery, mice underwent olfactory bulb ablation or sham operation, and were analyzed after 1, 2, or 4 weeks. Bulbectomized (BX) mice were anosmic, and hyperactive when tested under stressful situations in the forced swimming test. Predatory aggression was upregulated in a time-dependent way: only after 4 weeks BX mice were faster than controls in attacking prey. At the same time, they were less aggressive against intruders; they did not differ from controls in open field exploration, but displayed a cognitive impairment in water maze. Behavioral tests thus indicated a marked hyperreactivity, a dissociation among different aggressive behaviors, and also a cognitive impairment induced by bulbectomy. Histological confirmation of the damage revealed that major modifications took place in the rostral pole of frontal lobes, with a significant increase in the width of the rostral migratory stream, 2 weeks after surgery, and in the subventricular zone, 4 weeks after surgery. These results suggest a base for the time-course of appearance of behavioral symptoms in BX mice.
Insights
Olfactory bulbectomy in mice induces depression-like behaviors, hyperactivity, and cognitive deficits. These behavioral changes appear over time, correlating with specific brain alterations, providing a model for antidepressant drug screening.
Area of Science:
- Neuroscience
- Behavioral Science
- Pharmacology
Background:
- Olfactory bulbectomy (BX) in rodents creates a depression model used for antidepressant drug screening.
- Understanding the timeline of BX-induced behavioral changes is crucial for its application.
Purpose of the Study:
- To investigate the onset and progression of behavioral alterations following olfactory bulbectomy in mice.
- To correlate behavioral changes with underlying neuroanatomical modifications.
Main Methods:
- Mice underwent olfactory bulb ablation (BX) or sham surgery.
- Behavioral analyses (forced swimming, aggression tests, open field, water maze) were conducted at 1, 2, and 4 weeks post-surgery.
- Histological examination of frontal lobe modifications was performed.
Main Results:
- BX mice exhibited anosmia and hyperactivity in stressful conditions.
- Predatory aggression increased time-dependently (4 weeks post-BX).
- BX mice showed reduced aggression towards intruders and cognitive impairment in the water maze, but normal open field exploration.
Conclusions:
- Olfactory bulbectomy induces a complex behavioral phenotype including hyperreactivity, altered aggression, and cognitive deficits.
- The observed behavioral symptoms manifest with a specific time course, linked to structural changes in the frontal lobes.
- BX mice serve as a valuable model for studying depression and evaluating antidepressant therapies.
