Establishment and selection of tic disorder models in rats

Objective To observe the stereotypy and the movement of head in rat models of tic disorder (TD) induced by apomorphine (APO) or iminodipropionitrile (IDPN),and select the best method for making rat models fully reflecting the characteristic behavior change. Methods A total of 30 male SD rats weighing 100-110 g were randomly divided into APO inducement group, IDPN inducement group and control group (n=10).The rats in the APO inducement group were intraperitoneally injected 2 mg/kg APO, and those in the IDPN inducement group were intraperitoneally injected 150 mg/kg IDPN; equal volume of saline was injected into the rats of the control group; treatments were given daily for a consecutive 7 d at a dosing volume of 1 mL/100 g. The stereotypy scale scores were observed and recorded at 5-10 min,15-20 min,25-30 min,35-40 min,45-50 min and 55-60 min after the treatment.Movement of head was noted within 5 min of sucess model making. Results The head move number of the rats in the APO and IDPN inducement groups was significantly larger than that in the control group (P＜0.05); the head move number of the rats in the IDPN inducement group was obviously larger than that in the APO inducement group (P＜0.05).The stereotyped behavior scores of rats in the APO inducement group were significantly higher than those in the control group at 5-10 min,15-20 min,25-30 min,and 35-40 min after treatment (P＜0.05); those of rats in the IDPN inducement group were higher than those in the control group at every time interval (P＜0.05); those in the IDPN inducement group were higher than those in the APO inducement group at 45-50 min and 55-60 min after tre atment (P＜0.05).Conclusion The behavioral changes of TD models induced by IDPN are more obvious than those of models induced by APO; TD model induced by IDPN is an ideal animal model for observing tic disorder. Key words: Tic disorder; Animal model; SD rat; Stereotypy