Dynorphin Antagonism
Objective: To test the antidepressant-like effects of dynorphin antagonism in the nucleus accumbens using the learned helplessness paradigm
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Materials1
Not specified • Not specified • Not specified • Not mentioned
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Protocol Steps
Transgenic mouse development
Developed inducible transgenic lines of mice that express either CREB or a dominant-negative mutant of CREB (mCREB) in forebrain regions
Note: Two transgenic lines created with different CREB expression profiles
View evidence from paper
“developed inducible transgenic lines of mice that express either CREB or a dominant-negative mutant of CREB (mCREB) in forebrain regions”
Learned helplessness behavioral testing
Used learned helplessness paradigm as a behavioral model of depression to test transgenic mice
Note: This is a standard behavioral model for assessing depression-like behavior
View evidence from paper
“used these mice to determine the functional significance of this transcription factor in the learned helplessness paradigm, a behavioral model of depression”
Viral-mediated gene transfer to nucleus accumbens
Directly injected viral vector expressing mCREB into the nucleus accumbens to test localized effects
Note: Complementary approach to transgenic studies, targeting specific brain region
View evidence from paper
“use a complementary viral-mediated gene transfer approach to directly test the effect of mCREB in the nucleus accumbens, a brain region important for motivation and reward”
Assessment of CREB blockade effects
Evaluated antidepressant-like effects produced by blockade of CREB through overexpression of mCREB in transgenic mice or viral expression in nucleus accumbens
Note: Compared effects of CREB blockade versus CREB overexpression
View evidence from paper
“blockade of CREB by overexpression of mCREB in transgenic mice or by viral expression of mCREB in the nucleus accumbens produces an antidepressant-like effect”
Immunolocalization and expression analysis
Examined colocalization of mCREB with prodynorphin in nucleus accumbens medium spiny neurons and measured prodynorphin expression changes
Note: mCREB expression was found to decrease prodynorphin expression
View evidence from paper
“mCREB expression was colocalized with and decreased the expression of prodynorphin in nucleus accumbens medium spiny neurons”
Dynorphin antagonism testing
Tested antagonism of dynorphin in the nucleus accumbens to determine if it produces antidepressant-like effects
Note: Dynorphin antagonism produced effects similar to CREB blockade
View evidence from paper
“antagonism of dynorphin in the nucleus accumbens was sufficient to produce an antidepressant-like effect similar to that observed after blockade of CREB”