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

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

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. http://www.answers.com/topic/learned-helplessness

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

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

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

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)

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 30-60 seconds Escape latency The time from the start of shock to the escape response

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

Results continued…

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