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* These authors contributed equally
Presented here is a protocol to study depression-like and anhedonic behavior in rats. It combines two well-established behavioral methods, the sucrose preference and novelty-induced hypophagia tests, with an automated food and liquid intake monitoring system, to indirectly investigate rodent behavior using surrogate parameters.
The prevalence and incidence of depressive disorders are rising worldwide, affecting about 322 million individuals, underlining the need for behavioral studies in animal models. In this protocol, to study depression-like and anhedonic behavior in rats, the established sucrose preference and novelty-induced hypophagia tests are combined with an automated food and liquid intake monitoring system. Prior to testing, in the sucrose preference paradigm, male rats are trained for at least 2 days to consume a sucrose solution in addition to tap water. During the test, rats are again exposed to water and sucrose solution. Consumption is registered every second by the automated system. The ratio of sucrose to total water intake (sucrose preference ratio) is a surrogate parameter for anhedonia. In the novelty-induced hypophagia test, male rats undergo a training period in which they are exposed to a palatable snack. During training, rodents show a stable baseline snack intake. On test day, the animals are transferred from home cages into a fresh, empty cage representing a novel unknown environment with access to the known palatable snack. The automated system records the total intake and its underlying microstructure (e.g., latency to approaching the snack), providing insight into anhedonic and anxious behaviors. The combination of these paradigms with an automated measuring system provides more detailed information, along with higher accuracy by reducing measuring errors. However, the tests use surrogate parameters and only depict depression and anhedonia in an indirect manner.
On average, 4.4% of the world’s population is affected by depression. These account for 322 million people worldwide, an 18% increase compared to ten years ago1. According to estimates by the World Health Organization, depression will be second in the ranking of Disability Adjusted Life Years in 20202. To address the rising prevalence of affective disorders and establish new interventional strategies, it is necessary to further study this behavior. Prior and in addition to examination in humans, animal studies are necessary.
Several models have been established to study components of dep....
Animal care and experimental procedures followed the specific institutional ethics guidelines and was approved by the state authority for animal research.
1. Operation of the automated monitoring system
NOTE: When operating the automated monitoring system, it is crucial to document every action in the comment box included in the software immediately prior to the action. The description should be typed into the comment box, and by pressing Save, it is .......
To test data distribution, the Kolmogorov-Smirnov test was used. T-tests were used when data were normally distributed and Mann-Whitney-U test was used, if not. One-way ANOVA followed by Tukey post-hoc test was used for normally distributed multiple group comparison. One-way ANOVA followed by Dunn’s multiple comparison test was used in cases of non-normal distribution. Differences between groups were considered significant when p < 0.05.
The SPT was performed on naïve r.......
The sucrose preference and novelty-induced hypophagia tests are two established techniques for evaluating anhedonia in rats. Their combination with the automated food intake monitoring system allows for more detailed analysis in undisturbed rats and reduces erroneous measurement.
The incidence of errors is reduced by different approaches. First, to address the error occurring due to spillage, the gap between the food hopper and gate allows crumbs generated during gnawing to fall onto the integ.......
This work was supported by funding of the German Research Foundation (STE 1765/3-2) and Charité University Funding (UFF 89/441-176, A.S.).
....Name | Company | Catalog Number | Comments |
Assembly LH Cage Mount - RAT-FOOD - includes Stainless cage mount, hopper, blocker, coupling | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BCMPRF01 | |
Assembly LH Cage Mount unplugged - RAT - FOOD includes stainless steel cage mount, hopper, blocker, unplugged adapter, coupling | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BCMUPRF01 | |
cage w/ 2 openings - RAT - costum modified cage - includes cage top and standard water bottle | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BCR02 | single housing |
Data collection Laptop Windows - Configured w/ BioDAQ Software | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BLT003 | |
enrichment (plastic tubes, gnawing wood) | distributed by the animal facility | ||
HoneyMaid Graham Cracker Crumbs | Nabisco, East Hanover, NJ, USA | ASIN: B01COWTA98 | palatable snack for NIH test |
low vibration polymer rack | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BRACKR | |
male Sprague Dawley rats | Envigo | Order Code: 002 | |
Model #2210 32x Port BioDAQ Central Controller - includes cables, and calibration kit | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BCC32_03 | |
Peripheral sensor Controller - includes cable | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BPSC01 | |
SigmaStat 3.1 | Systat Software, San Jose, CA, USA | statistical analysis | |
Stainless steel blocker | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | BBLKR | |
standard rodent diet with 10 kcal% fat | Research Diets, Inc., Jules Lane, New Brunswick, NJ, USA | D12450B | |
sucrose powder | Roth | 4621.1 | for SPT |
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