Year of Entry into UCI MSTP

2007

Research Interests

Neuroscience

Hobbies and Interests

piano, ballet, salsa, biking, golfing, skiing

Hometown

Seattle, WA

Website

Department

Anatomy & Neurobiology

Academic Quarter

Summer 2008

Project Topic

Silencing the CRH Gene: a tool to unravel the mechanisms of experience-dependent plasticity of the stress system

Project Abstract

Rationale: The ‘tone’ (reactivity) of the HPA system contributes to an individual’s stress responses and vulnerability to depression and premature cognitive decline. In rat models, the neuroendocrine stress axis (hypothalamic-pituitary-adrenal axis, or HPA axis) is modulated through early-life events as demonstrated by the finding that enhanced maternal care (handling paradigm) produces persistent reduction in HPA axis activation. ‘Handled’ animals as adults show reduced corticotropin-releasing hormone (CRH) levels in the paraventricular nucleus of the hypothalamus (PVN), reduced stress-response, increased hippocampal glucocorticoid receptor and improved hippocampal-mediated learning and memory. Reduction in CRH gene expression is an early and essential step in the sequence of molecular changes that occur post-‘handling’ to produce these long-term effects, and can already be detected at the end of the handling paradigm on postnatal day 9 (P9). This research aims to investigate whether reduction of CRH in PVN is necessary and sufficient to induce the long-term handling phenotype. We hypothesize that experimentally reducing endogenous PVN-CRH expression in non-handled, undisturbed pups will recapitulate the ‘handling’ phenotype. Methods: RNA-mediated RNA interference was used to achieve site-specific silencing of hypothalamic peptides. Four pups (P9) were injected unilaterally with long double-stranded CRH directly into the PVN (coordinates from bregma (in mm): –1, –1). Levels of CRH were assessed 3 to 4 days later by in situ hybridization to confirm silencing. Results: Stereotaxically infused CRH dsRNA was successfully taken up by the hypothalamic cells, resulting in decreased CRH mRNA levels unilaterally in the PVN-specific site of injection. Conclusion: By using RNA interference we achieved the site specific silencing of CRH in the PVN. This provides us with a tool to experimentally decrease endogenous PVN-CRH and test whether the reduction of hypothalamic CRH levels will recapitulate the ‘handled’ phenotype.