%0 Journal Article
%T Marked Effects of Tachykinin in Myositis Both in the Experimental Side and Contralaterally: Studies on NK-1 Receptor Expressions in an Animal Model
%A Yafeng Song
%A Per S. St£¿l
%A Jiguo Yu
%A Sture Forsgren
%J ISRN Inflammation
%D 2013
%R 10.1155/2013/907821
%X Muscle injury and inflammation (myositis) in a rabbit model of an unilateral muscle overuse were examined. It is unknown if the tachykinin system has a functional role in this situation. In this study, therefore, the neurokinin-1 receptor (NK-1R) expression patterns were evaluated. White blood cells, nerve fascicles, fine nerve fibers, and blood vessel walls in myositis areas showed NK-1R immunoreaction. NK-1R mRNA reactions were observable for white blood cells and blood vessel walls of these areas. NK-1R immunoreaction and NK-1R mRNA reactions were also seen for muscle fibers showing degenerative and regenerative features. There were almost no NK-1R immunoreactions in normal muscle tissue. Interestingly, marked NK-1R expressions were seen for myositis areas of both the experimental side and the contralateral nonexperimental side. EIA analyses showed that the concentration of substance P in the muscle tissue was clearly increased bilaterally at the experimental end stage, as compared to the situation for normal muscle tissue. These observations show that the tachykinin system is very much involved in the processes that occur in muscle injury/myositis. The effects can be related to proinflammatory effects and/or tissue repair. The fact that there are also marked NK-1R expressions contralaterally indicate that the tachykinin system has crossover effects. 1. Introduction The tachykinins conform to a group of neuropeptides with marked functional roles. The neuropeptide which is most well known in the group is substance P (SP). SP has pronounced pro-inflammatory effects, including the promotion of extravasation and accumulation of leukocytes at sites of injury [1]. SP is also involved in the so-called neurogenic inflammation [2], wound healing [3], and angiogenesis [4]. SP is on the whole known to have autocrine/paracrine effects [5]. SP has a high affinity for the neurokinin-1 receptor (NK-1R), having its major functions via this receptor [6]. The NK-1R has 407 amino acids and belongs to the G-protein-coupled group of receptors [7]. The NK-1R can play an important role in the modulation of the accumulation of white blood cells that occurs in inflammatory processes [8]. There is frequently an upregulation of tachykinins in situations with inflammation and tissue injury. That includes the situation in, for example, ulcerative colitis [9] and experimentally induced acute pancreatitis and associated lung injury [10]. In the latter situation, the NK-1R is considered to play a key role in the damaging process [11]. It is actually a fact that the upregulation of
%U http://www.hindawi.com/journals/isrn.inflammation/2013/907821/