1. Effect of Neonatal Handling on Learned Helplessness Model of Depression
Costella, Tejedor-Real, Mico, & Rahola
Presented by Jamie Renspe
June 21, 2007

2. Prior Research
Handled rats exhibited attenuated (i.e. less) fearfulness in new environments
More exploratory behaviors
Low emotional reactivity
Shorter escape latencies in a shuttle-box
Increases the reactivity to foot shocks
Reduces cognitive, learning, and memory impairments in older rats

3. Model of Depression Learned Helplessness
A laboratory model of depression in which exposure to a series of unforeseen adverse situations gives rise to a sense of helplessness or an inability to cope with or devise ways to escape such situations, even when escape is possible.

4. Model of Depression Learned Helplessness
Prior Research
Lack of control
Lack of prediction

5. Question
Will rat handling during early postnatal periods make rats less susceptible to helplessness in adulthood?

6. Methods Conditions Control group Handled rats
These rats were left undisturbed in their cages
12 rats
Handled rats
Handled rats were removed from their cages and placed in a plastic container with a paper towel for 15 minutes every day
8 rats

7. Methods continued… Open field tests Induction of Learned Helplessness
Circular open fields
Measured emotivity counting the number of boluses excreted
Induction of Learned Helplessness
Electric foot shocks (US) paired with light (CS)

8. Methods continued… Escape and Avoidance Performance
Automated two-way shuttle box
2 chambers divided by a plastic partition or gate
Led into other compartment
Escape response
Would they attempt to escape?
Avoidance response
Escape failure
Failure for the rat to escape within seconds
Escape latency
The time from the start of shock to the escape response

9. Results
Handled rats excreted less boluses compared to non-handled rats during the second session of the open field test
Handled rats had less of an escape deficit
Handling reduced the mean escape latency after induction of helplessness during the shuttle box sessions
Handled rats made more avoidance responses after inescapable shock session

10. Results continued…

11. Results continued… Handling reduces the level of emotivity
Handling reduces the susceptibility of learned helplessness
Endogenous opioids
Opioid-peptides that are produced naturally in the body
An opioid is a chemical substance that has a morphine-like action in the body