Background & Aims
Neuropathic pain is a complex condition characterised by altered sensory processing and mood disturbances, which affects many individuals all over the world (6, 7). Behavioural assessments are crucial for understanding the impact of neuropathic pain on mood and cognition. Rats subjected to partial sciatic nerve ligation surgery develop neuropathic pain symptoms, making them a valuable model for studying these behavioural changes (3). This study aimed to assess the behavioural changes related to mood and cognition in a rat model of neuropathic pain. Specifically, we aimed to compare locomotor and exploratory behaviour and memory and learning between rats on day 14 and day 28 post-surgery. Understanding these behavioural changes can provide insights into the progression and management of neuropathic pain.
Methods
Adult male Sprague Dawley rats were used in this study. Neuropathic pain was induced by performing partial sciatic nerve ligation (PSNL) surgery (5). Rats were divided into four groups: 14 days control, 14 days PSNL, 28 days control and 28 days PSNL. Behavioural analyses were conducted to assess various parameters.
The von Frey filament test was used to assess mechanical allodynia. Rats were placed on an elevated mesh floor, and filaments of varying forces were applied to the hind paw to record the withdrawal threshold (1). The open-field test was employed to evaluate locomotor and exploratory behaviour. Rats were placed in a square arena, and their movements were tracked and analysed for parameters such as total distance travelled and the time spent in the centre versus the periphery (4). The novel object recognition was utilised to assess learning and memory. The time spent exploring the novel object was recorded as a measure of recognition memory (2).
Behavioural analyses were con
Results
The rats subjected to partial sciatic nerve ligation surgery developed mechanical allodynia, as evidenced by a decrease in withdrawal threshold. The pain threshold was significantly lower on day 14 post-surgery compared to day 28, indicating maximal pain on day 14 with a gradual decrease in pain over time.
Analysis of locomotor and exploratory behaviour revealed that the rats spent more time in the peripheral zone of the arena and covered less distance compared to the control group. This reduced activity could be attributed to pain-induced avoidance of movement or to mood disturbances such as depression, which can also lead to decreased mobility.
In the novel object recognition test, there was no significant difference in the time spent exploring the novel object between the two-time points. This suggests that the rats did not exhibit any deficits in learning and memory up to day 28 post-surgery.
Overall, these results indicate that rats in this neuropathic pain model experience maximal pain on day 14 post-surgery, with a gradual reduction in pain over time. While locomotor and exploratory behaviour are affected, possibly due to pain or mood disturbances, Learning and memory remain intact up to day 28 post-surgery.
Conclusions
This study provides valuable insights into the behavioural changes associated with neuropathic pain, highlighting the importance of understanding its impact on mood, cognition, and overall quality of life. The observed mechanical allodynia and alterations in locomotor and exploratory behaviour suggest a significant impact of neuropathic pain on daily activities and mobility. The lack of deficits in learning and memory indicates that these cognitive functions may remain unaffected in the early stages of neuropathic pain.
Understanding these behavioural changes is crucial, as they can have a profound impact on the quality of life of individuals suffering from neuropathic pain. Mood disturbances, such as depression and reduced mobility, can further exacerbate the already challenging nature of neuropathic pain, leading to a vicious cycle of decreased physical activity and social interaction.
This study contributes to the broader understanding of the condition by elucidating the behaviour
References
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Presenting Author
Saroj Kaler Jhajhria
Poster Authors
Saroj Kaler Jhajhria
M.B.B.S. M.D.
All India Institue of Medical Sciences
Lead Author
S Kamalesh
All India Institute of Medical Sciences
Lead Author
S B Ray
All India Institute of Medical Sciences
Lead Author
M Bishnoi
Santosh Medical College, Ghaziabad (U.P.)
Lead Author
Topics
- Models: Chronic Pain - Neuropathic