Different strains and substrains of rats show different levels of neuropathic pain behaviors

Abstract

This study compared and contrasted the manifestation of neuropathic pain behaviors in several strains of rats. These included ACI, Brown-Norway, Fischer 344, Lewis, Long-Evans, Sprague-Dawley, and Wistar-Furth, all obtained from Harlan Sprague-Dawley Inc. Comparison was also made between two substrains of Sprague-Dawley rats: one from Harlan and the other from Sasco. Neuropathic injury was produced by tightly ligating the left L5 and L6 spinal nerves with the animals under halothane anesthesia. Tests were conducted for 2 weeks to examine behavioral signs representing mechanical allodynia, cold allodynia, and spontaneous pain. There was no difference between strains in any of the tested behaviors before surgery. After neuropathic injury, rats in most groups developed high levels of behavioral signs of various components of neuropathic pain; however, some strains of rats showed weak behavioral signs of neuropathic pain. When a comparison was made between two substrains of Sprague-Dawley rats from two different sources, the ones from Sasco showed weaker behavioral signs than those from Harlan. When comparisons were made between different strains of rats from the same source (Harlan), Brown-Norway and Long-Evans rats showed the smallest magnitude of neuropathic pain behaviors. The data indicate that different strains and substrains of rats display different degrees of pain behaviors, suggesting that strains and substrains are important variables in the development of neuropathic pain after peripheral nerve injury.

Differences in forebrain activation in two strains of rat at rest and after spinal cord injury

“…In this study, the onset of excessive grooming behavior was slower in SD males than LE males, but the intensity of excessive grooming was greater in SD males. These results agree with previous reports related to the response to injury that show that SD rats exhibit significantly greater spontaneous pain, in addition to significantly greater mechanical and cold allodynia compared to LE rats (Yoon et al, 1999;Mills et al, 2001). The pattern of increase in neuronal activity of limbic structures in the present study may underlie the enhancement of these neuropathic behaviors in the SD strain after spinal injury.…”

“…Such strain-dependent variability in autonomy has subsequently been confirmed in both rats and mice (Panerai et al, 1987;Devor and Raber, 1990;Cohn and Seltzer, 1991;Carr et al, 1992;Defrin et al, 1996;Mogil et al, 1999). The role of genetic factors in neuropathic pain has also been confirmed in studies looking at spontaneous and/or evoked pain-like behaviors, allodynia, and hyperalgesia in rats or mice with peripheral nerve injury or in different models of spinal cord injury (SCI) (Mogil et al, 1999;Lovell et al, 2000;Mills et al, 2001;Yoon et al, 1999;DeLeo and Rutkowski, 2000;Xu et al, 2001;Wiesenfeld-Hallin et al, 1993;Gorman et al, 2001). …”

Significant Differences in the Effects of Magnetic Field Exposure on 7,12-Dimethylbenz(a)anthracene-Induced Mammary Carcinogenesis in Two Substrains of Sprague-Dawley Rats

“…However, it is well known that SD substrains, including SD substrains from the same provider, may show marked differences in a variety of responses (37)(38)(39)(40)(41)(42). SD rats are randomly outbred; hence, allelic variations can occur across vendors.…”

Chronic Constriction of the Sciatic Nerve and Pain Hypersensitivity Testing in Rats

“…Furthermore, the type of suture material used for ligating the nerve can also contribute to variability, and it is believed that chemicals from the chromic gut mediate some of the behavioural and neurochemical effects observed in this model 19,22 . Special consideration should be given to the choice of the rat gender (males versus females) 23 , age (young versus old) 24,25 , diet 26 and strain 27 , which can significantly influence the development of pain hypersensitivity following CCI.…”