Effect of Neonatal Handling on Learned Helplessness Model

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 n More exploratory behaviors n Low emotional reactivity n Shorter escape latencies in a shuttle-box n n n Increases the reactivity to foot shocks Reduces cognitive, learning, and memory impairments in older rats

Model of Depression Learned Helplessness n 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 n Lack of control n Lack of prediction n

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

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

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

Methods continued… n Escape and Avoidance Performance n Automated two-way shuttle box n 2 chambers divided by a plastic partition or gate n n Led into other compartment Escape response n Would they attempt to escape? n Avoidance response n Escape failure n Failure for the rat to escape within 30 -60 seconds n Escape latency n 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 n Handled rats had less of an escape deficit n Handling reduced the mean escape latency after induction of helplessness during the shuttle box sessions n Handled rats made more avoidance responses after inescapable shock session n

Results continued…

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