Strain difference in behavioral response to a new environment in rats

Area of Science:

• Neuroscience
• Animal Behavior
• Comparative Psychology

Background:

• Locomotor activity is a key indicator of an animal's response to novel environments.
• Strain differences in rats can influence their behavioral adaptation.
• Understanding adaptation capacity is crucial for selecting appropriate animal models in research.

Purpose of the Study:

• To investigate strain-specific differences in locomotor activity and adaptation to a new environment among Fischer 344 (F344), spontaneously hypertensive rats (SHR), and Wistar normotensive Kyoto rats (WKY).
• To evaluate the capacity for adaptation in these rat strains over a 5-day period.
• To determine the suitability of F344 and SHR as animal models for depression research based on their adaptation patterns.

Main Methods:

• Horizontal locomotor activity was measured using photocell-utilizing activity-recording devices over a 24-hour period.
• Activity levels were compared between the second day (1 day of adaptation) and the sixth day (5 days of adaptation).
• Three rat strains were used: Fischer 344 (F344), spontaneously hypertensive rats (SHR), and Wistar normotensive Kyoto rats (WKY).

Main Results:

• Wistar Kyoto rats (WKY) showed no significant difference in locomotor activity between day 2 and day 6, indicating good adaptation.
• Spontaneously hypertensive rats (SHR) exhibited higher activity on day 2 compared to day 6 during specific light and dark phases, suggesting poorer adaptation.
• Fischer 344 rats (F344) also showed higher activity on day 2 compared to day 6 during a significant portion of the light and dark phases, indicating poorer adaptation.

Conclusions:

• Spontaneously hypertensive rats (SHR) and Fischer 344 (F344) rats demonstrate a poorer capacity for environmental adaptation compared to Wistar Kyoto rats (WKY).
• The adaptation deficits observed in SHR and F344 rats resemble behavioral changes seen in depressive patients.
• These findings support the use of SHR and F344 rats as potentially suitable animal models for depression research.