Learning and Memory in Female Rats Effects of

Learning and Memory in Female Rats: Effects of a high fat diet and enriched environment Andrew Suter Behavioral Neuroscience Laboratory California State University, Bakersfield

Enriched Environments � Donald Hebb (1904 -1984) � Pioneered the field of environmental enrichment � Behavioral benefits � Improved performance in detour and maze tasks � Solved test problems more easily than their laboratory counterparts Impoverished Environment Enriched Environment

Enriched Environments and Brain Development � Mammals that are exposed to Enriched Environments show: � Greater survival of neurons (Nilsson et al. , 1999) � Increased dendritic branching ( Beauquis et al. , 2010) � Increased synapotgenesis (Birch et al. , 2013) � Increased neurogenesis (Römer et al. , 2011)

Enriched Environments & Neurogenesis Fig. 1. Effects of different housing conditions (8 weeks) on the number of Brd. U+ cells in the dentate gyrus (newborn granule cells) of young (2 months) and aged (25 months) rats male rats. Environmental enrichment significantly increased neurogenesis in the hippocampus of young and old rats compared with control housing conditions (Mora et al. , 2007, Brain Research Reviews)

Where is Neurogenesis Occurring? � Hippocampus � Short Term Memory into Long Term Memory Hippocampus Human Brain Rat Brain

Enriched Environments & Learning and Memory in Male rats Rats placed in Enriched Environments have better memory Morris Water Maze Qiu et al. , 2012

Neurogenesis, High Fat Diet, And Sex 4 weeks of high fat diet resulted in significant reduction of neurogenesis in male rats, and not in female rats. But not in females …. however Lindqvist et al. (2006)

Rational & Research Question � Given that we know enriched environments lead to: � Increased neurogenesis in the areas of the brain that play a role in learning and memory � And Given that we know a high fat diet leads to: � Decreased neurogenesis in the hippocampus � And that this effect is different in males and females… We wanted to compare the behavioral effects (spatial learning) of a high fat diet in male and female rats kept in enriched environments

6 mo later @ 16 mo Standard Environment Enriched Environment (Female) Enriched Environment (Male)

6 mo later @ 16 mo Standard Rodent Chow (11% fat) #5001 Purina, USA Western Diet (39% fat) AIN-93 G, Research Diets, NJ, USA

6 mo later @ 16 mo

8 -Arm Radial Maze: Test of Spatial Learning Arms: 61 cm L, x 23 cm W, x 23 cm H Measure of: Short-Term: each trial Long-Term: over the 8 days

Design & Analysis 2 X 2 X(8) Mixed Design Between: Environment & Diet Enriched Environment Standard Chow n =14 High Fat Diet N=14 Standard Rat Cage Standard Rat Chow n=14 High Fat Diet n=14 Within: 8 Days of Testing DV: Errors in 8 -Arm Maze DV : Time to Complete Task Mixed Design 2 X 2 X(8) ANOVA

Female Errors in 8 -Arm Radial Maze 4 month 10 month 16 month

Summary of Finding Memory: Errors � High fat diets contributed negatively to memory in female rats. � Regardless of diet, female rats housed in enriched environments showed significant improvement in spatial memory. � These data show that females are similarly effected by a high fat diet despite a lack of change in neurogenesis Time: � Rats on a high fat diet completed the task slower than their standard chow counterparts in both environmental conditions (data not shown) In both males and females, Enriched Environments have a positive impact

Translation to Humans � � Diet may impact children’s learning Long-term impacts of childhood diet may be ameliorated by an enriched environment

Future Research � � Analyze Phase 4 of testing (April, 2016) Longitudinal comparison to Male data Presenting at Society for Neuroscience New Projects!

Acknowledgements Faculty Mentor: Dr. Isabel Sumaya BNL Supervisor Samirah Hussain The Rats! CSU SRS Program Gayle & Ben Batey Fund for the Neurosciences BNL Assistants: Christine Dawson Lyncie Fink Sukhi Momi Nayeli Ramirez Monica Rosas Susie Villarreal

Behavioral Neuroscience Lab