Comparison of the behavioral effects of exercise and high fat diet on cognitive function in adolescent rats

A long-term mild high-fat diet facilitates rabbit discrimination learning and alters glycerophospholipid metabolism

Previous reports have shown an association between a Western high-fat diet (HFD) and poor cognitive performance. So far, there are no reports of whether a mild HFD can affect rabbit learning and hippocampal metabolic profile. This study was designed to explore whether feeding a mild HFD (5 % lard and 5 % soy oil) for 20 weeks affected eyeblink discrimination and discrimination reversal learning and hippocampal metabolic profiles. After 20 weeks on the HFD or a normal control diet, all rabbits received one day of adaptation, 20 daily sessions of two-tone discrimination (1-kHz CS + followed by air puff and 8-kHz CS- not followed by air puff), a rest day, and then 40 daily sessions of discrimination reversal (8-kHz CS + and 1-kHz CS-). Compared to rabbits fed a regular chow diet, rabbits fed a mild HFD showed better discrimination evidenced by higher responding to CS+, lower responding to CS-, and a larger discrimination index (CS+ - CS-). Widely targeted metabolomics analysis identified 1805 metabolites in the hippocampus, and significant HFD-induced changes in 162 and 165 differential metabolites in males and females, respectively. These included glycerophospholipids and fatty acyls. KEGG enrichment analysis showed glycerophospholipid metabolism (ko00564) was significantly enriched in the HFD group notably lysophosphatidylethanolamine and lysophosphatidylcholine. In summary, our data show a long-term mild HFD facilitated discrimination learning in rabbits without inducing a metabolic syndrome, and altered the hippocampal metabolic profile, which may affect neuronal cell membrane lipids and behavioral performance.

Physical exercise consequences on memory in obesity: A systematic review

Obesity is associated with changes in memory. Thus, the aim of this systematic review was to investigate the physical exercise consequences on memory in obesity. A search was carried out in the PubMed, Lilacs, and Scielo databases with the following descriptors: "physical exercise," "memory," and "obesity." A total of 16 studies were analyzed in this review. Low, moderate, and high intensity exercise training showed positive effects on memory in patients with obesity (100%). The animal models of obesity used in their physical exercise protocols: treadmill (72.7%) or wheel running (27.3%). Most of the animal studies (81.8%) revealed positive effects of the physical exercise protocol on memory in obesity. Mouse was the most commonly used animal (54.5%), and a 60% high-fat diet (HFD) was the most commonly method used to induce obesity (82%). We did not identify any knockout model of obesity that was used to evaluate memory and used physical exercise as the main intervention. Thus, exercise training, independently if it is resistance or endurance training, seems to be an excellent intervention to prevent and inhibit cognitive impairment and memory loss on obese patients and animal models of obesity.

Chronic Mild Unpredictable Stress and High-Fat Diet Given during Adolescence Impact Both Cognitive and Noncognitive Behaviors in Young Adult Mice

Stress and diet are intricately linked, and they often interact in a negative fashion. Increases in stress can lead to poor food choices; adolescence is a period that is often accompanied by increased levels of stress. Stress and poor dietary choices can affect learning and memory; it is important to understand their combined effects when occurring during crucial developmental periods. Here, we present evidence that chronic mild unpredictable stress (CMUS) and high-fat diet (HFD) impact both cognitive and noncognitive behaviors when assessed after four weeks of manipulation in four-week old mice. CMUS mice had increased anxiety in the open field test (OFT) (p = 0.01) and spent more time in the open arms of the elevated zero maze (EZM) (p < 0.01). HFD administration was shown to interact with CMUS to impair spatial memory in the Morris Water Maze (MWM) (p < 0.05). Stress and diet also led to disturbances in non-cognitive behaviors: CMUS led to significantly more burrowing (p < 0.05) and HFD administration led to the poorer nest construction (p < 0.05). These findings allow for researchers to assess how modifying lifestyle factors (including diet and stress) during adolescence can serve as a potential strategy to improve cognition in young adulthood.

Effects of endurance exercise and Urtica dioica on the functional, histological and molecular aspects of the hippocampus in STZ-Induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Many body systems and organs, including the hippocampus, are affected by diabetes, and undergo changes that may increase the risk of cognitive decline. Urtica dioica (UD) has long been recognized as a medicinal plant with beneficial effects on blood glucose control in diabetes.

AIM OF THE STUDY

The present study aimed to investigate the effect of endurance exercise (Ex), along with Urtica dioica (UD) hydro-alcoholic extract on some functional, histological, and molecular aspects of the hippocampus in streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

60 male Wistar rats were divided into five groups (N = 12): healthy control (H-C), diabetes control (D-C), diabetes exercise (D-Ex), diabetes Urtica dioica (D-UD), and diabetes exercise Urtica dioica (D-Ex-UD). Diabetes was induced intraperitoneally by STZ (45 mg/kg) injection. Two weeks after the injection by STZ, Ex (moderate intensity/5day/week) and gavage of UD extract (50mg/kg/day) was performed for six weeks. Cognitive functions were evaluated by the Morris Water Maze test, routine histological examination, and molecular studies were done via Hematoxylin & Eosin stain, and Western blot.

RESULTS

Diabetic rats showed spatial learning and memory deficits, as well as negatively affects to the tissue and structure of the hippocampus in the dentate gyrus (DG) and cornu ammonis (CA) areas. Ex + UD treatment caused a decrease of neural disorganization, an increase of neural-microglial density, and thickness of the pyramidal-molecular layer in the hippocampus. In addition, Ex + UD caused a rise of GAP-43 protein levels, a reduction of CAP-1 protein levels, improved hippocampal structure, and improved learning and memory function.

CONCLUSIONS

These results show that Ex, along with the UD extract, may decrease levels of the central neural complications of diabetes. Given the importance of recognizing non-pharmacological complementary therapies in this field, future studies are warranted.