Yoon Ju Cho

Rewarding and reinforcing effects of the NMDA receptor antagonist-benzodiazepine combination, Zoletil®: difference between acute and repeated exposure.

Zoletil(®) is a 1:1 combination of the N-methyl-d-aspartate (NMDA) receptor antagonist, tiletamine, and the benzodiazepine, zolazepam, commonly used as a veterinary anesthetic. There have been previous reports on the abuse of zoletil in humans, and these motivated us to investigate the rewarding and reinforcing effects of the drug. We experimented whether zoletil and its constituents, tiletamine and zolazepam, produces place preference and/or facilitates self-administration. Then we compared the effects of zoletil to that of the recreationally abused veterinary anesthetic, ketamine. We also delved into the consequences of drug pre-exposure, thus parallel experiments were performed on rats pre-treated with the drug for 14 days. Our findings indicated that zoletil produced neither reward nor reinforcement in drug-naïve rats; however, repeated pre-treatment of zoletil produced significant place preference and self-administration. Tiletamine generated both place preference and self-administration; while zolazepam induced place preference but was not self-administered, even in pre-treated animals. The rewarding and reinforcing effects produced by zoletil were comparable to that of ketamine. Therefore, zoletil per se, has no motivational effects but the changes in neuronal functions and behavior consequential to repeated zoletil treatment may contribute in part to the addiction liability of the drug. Furthermore, the present study suggests that complex interactions occur with acute or repeated treatment of an NMDA receptor antagonist-benzodiazepine combination.

Inhaled hydrogen gas therapy for prevention of testicular ischemia/reperfusion injury in rats

PURPOSE This study evaluated whether 2% hydrogen (H(2)) gas therapy protects against testicular ischemia/reperfusion injury which results in increased formation of reactive oxygen species and/or reactive nitrogen species, leading to testicular apoptosis and impaired spermatogenesis. METHODS Pubertal six-week-old Spraque-Dawley rats were assigned to 5 groups (10 animals/group) as follows: group A was a sham operated group; groups B, C, D, and E underwent 5 hours of left testicular ischemia followed by 0, 30, 60, and 120 minutes of 2% H(2) gas therapy, respectively. Histological analysis was performed to verify structure and morphology of the testes and to investigate Johnsen scores, mean seminiferous tubule diameter, and the number of germ cell layers to classify spermatogenesis. Germ cell apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay and Bax/Bcl-2 ratio real-time polymerase chain reaction. We also investigated malondialdehyde levels as an indicator of lipid peroxidation. RESULTS Compared to the sham group (A), germ cell apoptosis and lipid peroxidation in the ischemia group (B) were significantly increased with abnormal morphology and impaired spermatogenesis. In contrast, amelioration of testicular damages was evident in the H(2) therapy groups (C, D, and E). CONCLUSIONS Our results showed that inhalation of 2% H(2) gas may be a promising therapy with anti-apoptotic and anti-oxidant properties in cases of testicular ischemia/reperfusion injury.

Protective effect of pterostilbene on testicular ischemia/reperfusion injury in rats

PURPOSE To evaluate protective effect of pterostilbene against testicular ischemia/reperfusion (I/R) injury, which results in increased formation of oxidative stress, leading to testicular apoptosis and impaired spermatogenesis. METHODS Thirty two pubertal male Sprague-Dawley rats weighing 180-220g were selected and randomly divided into the following four groups: group A (normal control group), group B (sham-operated group), group C (induced I/R injury group), group D (induced I/R injury group receiving pterostilbene treatment). Johnsens scores and mean seminiferous tubule diameters were evaluated for histopathologic assessment; germinal cell apoptosis was evaluated by the transferase dUTP nick end labeling (TUNEL) assay and immunohistochemistry for caspases. Malondialdehyde (MDA) levels were assessed as an indicator of oxidative stress and total antioxidant capacity (TAC) was measured. RESULTS Germ cell apoptosis and MDA level significantly increased whereas TAC significantly decreased in group C; moreover, abnormal morphology and impaired spermatogenesis were observed in group C. In contrast, treatment with pterostilbene inhibited lipid peroxidation and apoptosis induced by ROS and restored the antioxidant capacity in group D. CONCLUSIONS These results show that treatment with pterostilbene may be a promising therapy for testicular I/R injury.

Kinetics of proinflammatory cytokines after intraperitoneal injection of tribromoethanol and a tribromoethanol/xylazine combination in ICR mice

Tribromoethanol (2,2,2-tribromoethanol, TBE) is a popular injectable anesthetic agent used in mice in Korea. Our goal was to assess the risks associated with side effects (lesions) in the abdominal cavity, especially at high doses. To understand the underlying pathophysiological changes, we examined levels of cytokines through ELISA of abdominal lavage fluid and spleen collected from mice treated with low and high-dose TBE. ICR mice were anesthetized using one of the following protocols: a combination of TBE 200 mg/kg (1.25%) and xylazine 10 mg/kg; TBE 400 mg/kg (1.25%); and TBE 400 mg/kg (2.5%). Administration of high-dose TBE (400 mg/kg) increased the interleukin-1β and interleukin-6 levels in the peritoneal cavity over the short term (<1 day) compared with sham controls and low-dose TBE (200 mg/kg) groups. Cytokine expression in the low-dose TBE group was similar to the control group, whereas in the high-dose TBE group cytokine levels were higher in abdominal lavage fluid and spleen over the long term (10 days post-injection). We conclude that a combination of TBE 200 mg/kg (1.25%) and xylazine (10 mg/kg) is a safe and effective anesthetic for use in animals.