Long-term consumption of capsicum annum (chilli pepper) and capsaicin diets suppresses pain perception and improves social behaviour of CD-1 mice

Purpose Chilli pepper (Capsicum annum), an extensively cultivated vegetable, is commonly used to spice many dishes prepared in several parts of the world. It contains capsaicinoids. The most active amongst these capsaicinoids is capsaicin (8-methyl-N-vanillyl-6-nonenamide), which is neurogenic and so may affect nervous function. Therefore, the purpose of this paper is to investigate the effects of long-term consumption of chilli pepper and capsaicin diets on pain and social behaviour in CD-1 Swiss white mice. Design/methodology/approach In total, 30 male mice were randomly assigned into three groups of ten mice each, namely, control, pepper-diet (20 per cent w/w) and capsaicin-diet (10 per cent w/w) groups. Tail immersion, hot plate and formalin tests were conducted to assess pain perception, while nesting behaviour test was used to evaluate the social behaviour of the mice. Findings The latency of tail flick of both the pepper and capsaicin groups were significantly longer (p < 0.01 and p < 0.001, respectively) compared to control. The hind paw lick frequency, duration and flinching of both the pepper and capsaicin groups were also significantly reduced compared to control. The nesting score of the capsaicin group was significantly higher (p < 0.01) compared to control. However, the nesting score for pepper group was significantly lower (p < 0.05) compared to capsaicin group. Originality/value Long-term consumption of capsaicin and pepper diets suppressed pain and enhanced organized social behaviour in mice. One of the active principles responsible for the effects obtained with pepper on pain and social behaviour in mice may be capsaicin.