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Functional Interrogation of Adult Hypothalamic Neurogenesis with Focal Radiological Inhibition
Published on: November 14, 2013
Metabolic and behavioral alterations associated with viral vector-mediated toxicity in the paraventricular
Rohan Savani1,2, Erin Park1,2, Nidhi Busannagari1,2
1The Child Health Institute of New Jersey, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA.
Objective:
Combining adeno-associated virus (AAV)-mediated expression of Cre recombinase with genetically modified floxed animals is a powerful approach for assaying the functional role of genes in regulating behavior and metabolism. Extensive research in diverse cell types and tissues using AAV-Cre has shown it can save time and avoid developmental compensation as compared to using Cre driver mouse line crossings. We initially sought to study the impact of ablation of corticotropin-releasing hormone (CRH) in the paraventricular hypothalamic nucleus (PVN) using intracranial AAV-Cre injection in adult animals.
Methods:
In this study, we stereotactically injected AAV8-hSyn-Cre or a control AAV8-hSyn-GFP both Crh-floxed and wild-type mouse PVN to assess behavioral and metabolic impacts. We then used immunohistochemical markers to systematically evaluate the density of hypothalamic peptidergic neurons and glial cells.
Results:
We found that delivery of one specific preparation of AAV8-hSyn-Cre in the PVN led to the development of obesity, hyperphagia, and anxiety-like behaviors. This effect occurred independent of sex and in both floxed and wild-type mice. We subsequently found that AAV8-hSyn-Cre led to neuronal cell death and gliosis at the site of viral vector injections. These behavioral and metabolic deficits were dependent on injection into the PVN. An alternatively sourced AAV-Cre did not reproduce the same results.
Conclusions:
Our findings reveal that delivery of a specific batch of AAV-Cre could lead to cellular toxicity and lesions in the PVN that cause robust metabolic and behavioral impacts. These alterations can complicate the interpretation of Cre-mediated gene knockout and highlight the need for rigorous controls.
Insights
A specific adeno-associated virus Cre preparation caused obesity and anxiety in mice by damaging the paraventricular nucleus. This highlights the need for rigorous controls in gene function studies.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Adeno-associated virus (AAV)-mediated Cre recombinase expression is a key tool for gene function studies.
- AAV-Cre offers advantages over traditional Cre driver mouse lines for temporal and spatial gene manipulation.
Approach:
- Stereotactic injection of AAV8-hSyn-Cre or AAV8-hSyn-GFP into the paraventricular hypothalamic nucleus (PVN) of Crh-floxed and wild-type mice.
- Immunohistochemical analysis to assess neuronal and glial cell density.
Key Points:
- One AAV8-hSyn-Cre preparation induced obesity, hyperphagia, and anxiety-like behaviors in mice.
- This effect was independent of sex and mouse genotype (floxed vs. wild-type).
- AAV8-hSyn-Cre caused neuronal cell death and gliosis in the PVN, leading to behavioral and metabolic deficits.
Conclusions:
- Specific AAV-Cre batches can exhibit cellular toxicity, causing lesions in the PVN.
- These toxic effects can confound gene knockout studies and necessitate stringent control experiments.
- The findings underscore the importance of batch validation for viral vectors in neuroscience research.
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