GABAB3-siRNA對GABA受體亞單位β-3 (GABAB3)的抑制顯著降低了NIH 3T3細胞中的Col1含量，說明了GABAB3介導了GABA誘導的Col1產生的過程。真皮內注射磷酸三鈣進入ICR小鼠背部皮膚能夠引起皮膚瘙癢。局部應用GABA或高GABA含量(BA菌共同培養生長)之稻米增加了Col1的產生，並減緩了磷酸三鈣誘導的瘙癢和IL-6含量之增加。 ;Skin is the largest and most visible organ in human body. Itchy skin, also known as pruritus, is an irritating and an uncomfortable sensation that associated with the desire to scratch for enhancement the feeling. Chronic itching induces inflammation and sustains production of interleukin (IL)-6, which can lead to epidermal hyperplasia. On the other hand, the formation of wrinkles is part of the aging associated with degradation of the collagen. Type I collagen (Col1) produced by fibroblasts is the main type of the collagen in the human skin. Gamma-aminobutyric acid (GABA) is well known as an inhibitory neurotransmitter in the central nervous system. Recent studies have reported the significant effect of GABA on wound healing and its function as an immune-modulator. It is reported that plant growth-promoting endophytic bacteria can stimulate the growth, nutrient acquisition, symbiotic performance and stress tolerance of plants. Here, we incubated rice grains with Bacillus amyloliquefaciens (BA), a non-pathogenic soil bacterium. Our results demonstrated that incubation of rice grains with BA bacteria did not change the lengths of roots and sprouts, but significantly increased the content of GABA. Treatment of 1mM and 10mM GABA significantly up-regulated the protein level of Col1 in NIH 3T3 cells. Furthermore, the expression of Col1 mRNA transcript was increased in NIH 3T3 cells when cells were treated with GABA in a dose-dependent manner. Inhibition of GABA receptor subunit beta-3 (GABAB3) by GABAB3-siRNA considerably reduced the Col1 in NIH 3T3 cells, indicating the GABAB3 mediated the GABA-induced Col1 production. Intra-dermal injection of tri-calcium phosphate (Ca3(PO4)2) into the dorsal back skin of ICR mice caused itching. Topical application of GABA or GABA-rich (BA-colonized) rice onto mouse skin augmented the production of Col1 and attenuated the tri-calcium phosphate-induced decreases in itching and the level of IL-6.
