Objective To optimize the optimal doses of histamine and 4-aminopyridine (4-AP) in the establish-ment of guinea pigs models of itching, and to establish a new guinea pig model of itching. Methods The central composite design-response surface method was used to arrange the experiment. In the experiment different pruritus agents were hypo-dermically injection of 0. 5 mL in the depilated area, and the scratching incubation period and scratching number in 30 mi-nutes were counted after the injection. The guinea pig itching model was evaluated by observing the behavioral changes of guinea pigs and measuring the levels of histamine and interleukin-6 in the blood. Results The behavioral experiments found that the scratching frequency in the the combination group was significantly higher than the histamine group and 4-AP group (P<0. 01). The itching latency of the combination group was significantly shorter than that of the histamine group and 4-AP group (P<0. 01). Compared with the control group, the histamine concentrations of the combination group and histamine group were significantly increased ( P<0. 05 or P<0. 01 ) , and the level of the combination group was lower than that of the histamine group (P<0. 05). Compared with the control group, the serum IL-6 concentrations of histamine group, 4-AP group and combination group were significantly higher (P<0. 01 or P<0. 05), and those in the combination group were significantly higher than the histamine and 4-AP groups. Compared with the control group, pathologic examina-tion showed proliferation of inflammatory cells in all model groups, and the reaction of the combination group was more ob-vious. Conclusions The optimal conditions used in this experiment are easy to achieve and have good reproducibility in the establishment of a guinea pig model of itching.

"Jinchai Shihu" were called Jinchai and recoded in "Taishang Zhouhou Yujingfang" of Tang Dynasty, which first clearly documented the name of Shihu in complex Dendrobium medicines and were condiered as superior medicinal articles. Morphological features are one of the naming principles for Chinese medicines. In this paper, botanical origin plants under the names of "Jinchai" and "Jinchai Shihu" were investigated. Based on documents from the local Chronicles and historical accounts, the Chinese characters of Jinchai have the distinctive features of gold color and two hair clasps. Moreover, the hair clasps are usually cylindrical in shape with uniform thickness in middle and upper part, and tapers off to the foot. And its bottom part style is simple and head part is complex. Thus we speculated the herbal "Jinchai" and "Jinchai Shihu" should have similar morphologic features as Chinese characters of Jinchai, including golden color and hairpin shape of stems without braches, short and solid sterm. After comparing the dried vegetative morphology of 10 common medicinal Dendrobium species, we suggested that of Dendrobium flexicaule matches well with the morphological features from historical herbal records.