Δ9-Tetrahydrocannabinol elicited 22-kHz ultrasonic vocalization changes after air puff stimulus through CB1 receptor in adult rats.

Δ9-Tetrahydrocannabinol (THC) is known to have various pharmacological effects mediated through activation of cannabinoid CB1 and CB2 receptors in rodents. In adult rats, 22- and 50-kHz ultrasonic vocalizations (USVs) serve as an effective communication system and as indicators of negative and positive states, respectively. The present study was performed to determine whether THC affects USVs in adult rats, and to determine the roles of cannabinoid receptors in these effects. THC (1, 3 mg/kg) was administered intraperitoneally to adult male Wistar rats 60 min before measurement of USVs. The CB1 antagonist, SR141716 (3, 6 mg/kg), or CB2 antagonist, AM630 (1, 10 mg/kg), was administered intraperitoneally 10 min before THC. USVs were measured during a 5-minute period without air puff stimulus or with air puff stimulus. THC did not affect 22- or 50-kHz USVs without air puff stimulus. On the other hand, THC significantly increased the number of 22-kHz USVs, but not 50-kHz USVs, after air puff stimulus. Moreover, SR141716 at 6 mg/kg, but not AM630 at either dose, inhibited the increase in number of 22-kHz USVs induced by THC after air puff stimulus. These results suggest that THC induced changes in sensitivity to aversive air puff stimuli through CB1 receptors, and as a result increased emission of 22-kHz USVs in rats.

Long-Term Treatment with Thrombomodulin Improves Functional Outcomes after Cerebral Ischemia Even if Administration is Delayed.

Our previous study indicated that recombinant human soluble thrombomodulin (rhsTM) could attenuate brain damage when administered as a bolus in the cerebral ischaemic early phase. Then, we considered that treatment with rhsTM may show therapeutic effects even when administered in the ischaemic delayed phase, because rhsTM has an action of inhibiting high-mobility group box 1 (HMGB1) as a late mediator of lethal systemic inflammation. This study was performed to investigate the effects of delayed treatment with rhsTM on ischaemic brain damage induced by high HMGB1 level in mice subjected to 4-hour middle cerebral artery occlusion (MCAO). One day after MCAO, rhsTM was administered intraperitoneally at a dose of 1 or 5 mg/kg once a day for 7 days. Neurological score, motor coordination and HMGB1 levels were measured 1, 3 and 7 days after MCAO. The presence of activated microglia was evaluated 7 days after MCAO. Systemic HMGB1 levels increased 1 to 7 days after MCAO and were higher at 7 days compared with day 1. At the same time, survival rate decreased, and activated microglia increased in the infarct area. Treatment with rhsTM improved neurological score, motor coordination, survival and prevented brain damage. Moreover, rhsTM decreased both HMGB1 level and number of activated M1 microglia. The results of this study indicated that rhsTM improved functional outcomes via inhibition of HMGB1 up-regulation and M1 microglial activation in the cerebral ischaemic delayed phase. rhsTM may become a new therapeutic agent with a wide therapeutic time window in patients with cerebral ischaemia.

Goreisan Prevents Brain Edema after Cerebral Ischemic Stroke by Inhibiting Aquaporin 4 Upregulation in Mice.

BACKGROUND: Aquaporin 4 (AQP4) is a water-selective transport protein expressed in astrocytes throughout the central nervous system. AQP4 level increases after cerebral ischemia and results in ischemic brain edema. Brain edema markedly influences mortality and motor function by elevating intracranial pressure that leads to secondary brain damage. Therefore, AQP4 is an important target to improve brain edema after cerebral ischemia. The Japanese herbal Kampo medicine, goreisan, is known to inhibit AQP4 activity. Here, we investigated whether goreisan prevents induction of brain edema by cerebral ischemia via AQP4 using 4-hour middle cerebral artery occlusion (4h MCAO) mice. METHODS: Goreisan was orally administered at a dose of 500 mg/kg twice a day for 5 days before MCAO. AQP4 expression and motor coordination were measured by Western blotting and rotarod test, respectively. RESULTS: Brain water content of 4h MCAO mice was significantly increased at 24 hours after MCAO. Treatment with goreisan significantly decreased both brain water content and AQP4 expression in the ischemic brain at 24 hours after MCAO. In addition, treatment with goreisan alleviated motor coordination deficits at 24 hours after MCAO. CONCLUSIONS: The results of this study suggested that goreisan may be a useful new therapeutic option for ischemic brain edema.

Role of vasopressin V1a receptor in ∆9-tetrahydrocannabinol-induced cataleptic immobilization in mice.

RATIONALE: Cannabis is a widely used illicit substance. ∆9-tetrahydrocannabinol (THC), the major psychoactive component of cannabis, is known to cause catalepsy in rodents. Recent studies have shown that vasopressin V1a and V1b receptors are widely distributed in the central nervous system and are capable of influencing a wide variety of brain functions such as social behavior, emotionality, and learning and memory. OBJECTIVES: The present study was designed to examine the possible involvement of V1a and V1b receptors in THC-induced catalepsy-like immobilization. METHODS: The induction of catalepsy following treatment with THC (10 mg/kg, i.p.) or haloperidol (1 mg/kg, i.p.) was evaluated in wild-type (WT), V1a receptor knockout (V1aRKO), and V1b receptor knockout (V1bRKO) mice. The effect of treatment with the selective 5-hydroxytryptamine1A receptor antagonist WAY100635 (0.1 mg/kg, i.p.) on THC-induced catalepsy was also evaluated in V1aRKO mice. Moreover, the effects of the V1a receptor antagonist VMAX-357 and the V1b receptor antagonist ORG-52186 on THC-induced catalepsy were evaluated in ddY mice. RESULTS: THC and haloperidol markedly caused catalepsy in V1bRKO mice as well as in WT mice. However, V1aRKO mice exhibited a reduction in catalepsy induced by THC but not by haloperidol. WAY100635 dramatically enhanced THC-induced catalepsy in V1aRKO mice. Although VMAX-357 (10 mg/kg, p.o.) but not ORG-52186 significantly attenuated THC-induced catalepsy, it had no significant effect on the enhancement of THC-induced catalepsy by WAY100635 in ddY mice. CONCLUSIONS: These findings suggest that V1a receptor regulates THC-induced catalepsy-like immobilization.

Involvement of Charcot-Marie-Tooth disease gene mitofusin 2 expression in paclitaxel-induced mechanical allodynia in rats.

Paclitaxel induces peripheral neuropathy, which is dose-limiting and results in loss of quality of life. Therefore, the prevention and treatment of paclitaxel-induced peripheral neuropathy are major concerns in clinical cancer therapy. However, the detailed mechanisms have not been fully elucidated. It has recently been reported that allelic variability in the Charcot-Marie-Tooth disease (CMT) genes, mitofusin 2 (MFN2), Rho guanine nucleotide exchange factor 10 (ARHGEF10), and periaxin (PRX), affected paclitaxel-induced peripheral neuropathy in clinical cases. Therefore, we hypothesized that paclitaxel may induce peripheral neuropathy due to changes in Mfn2, Arhgef10, and Prx mRNA expression. Paclitaxel (6mg/kg) was administered intraperitoneally, on two consecutive days per week for 4 weeks in rats. Paclitaxel-induced peripheral neuropathy was measured by the von Frey test and acetone test, mechanical allodynia, and cold hyperalgesia, respectively, on days 0, 3, 10, 17, and 24. Mfn2, Arhgef10, and Prx mRNA expression in the spinal cord were analyzed by qRT-PCR on days 3 and 24. Paclitaxel induced mechanical allodynia from days 17-24, but did not induce cold hyperalgesia. In addition, paclitaxel reduced Mfn2 mRNA expression, but not Arhgef10 or Prx mRNA expression, on days 3 and 24. In addition, Mfn2 mRNA level was decreased before the appearance of mechanical allodynia. The results of the present study suggest that a reduction in Mfn2 mRNA expression contributes to paclitaxel-induced mechanical allodynia.