Evaluation of the role of striatal cannabinoid CB[1] receptors on movement activity of parkinsonian rats induced by reserpine

It has been observed cannabinoid CB[1] receptor signaling and the levels of endocannabinoid ligands significantly increased in the basal ganglia and cerebrospinal fluids of Parkinson's disease [PD] patients. These evidences suggest that the blocking of cannabinoid CB[1] receptors might be beneficial to improve movement disorders as a sign of PD. In this study, a dose-response study of the effects of intrastriatal injection of a cannabinoid CB[1] receptor antagonist, AM251 and agonist, ACPA, on movement activity was performed by measuring the catalepsy of reserpinized and non-PD [normal] rats with bar test. Also the effect of co-administration the most effective dose of AM251 and several doses of ACPA were assessed. AM251 decreases the reserpine induced catalepsy in dose dependent manner and ACPA causes catalepsy in normal rats in dose dependant manner as well. AM251 significantly reverse the cataleptic effect in all three groups [1, 10, 100ng/rat] that received ACPA. These results support this theory that cannabinoid CB[1] receptor antagonists might be useful to alleviate movement disorder in PD. Also continuance of ACPA induced catalepsy in induced catalepsy. Based on the present finding there is an incomplete overlapping between cannabinoid CB[1] receptor agonist and antagonist effects

[Mechanism of the interaction of cannabinoid system in central amygdale with opioid system]

Cannabinoids which are active compounds of marijuana show some pharmacological effects similar to the opioids. There are also functional interactions between both cannabinoid and opioid systems. In this study we investigated the role of cannabinoid receptors in central amygdala and its interaction with opioid system. In the present study, we investigated the effects of intraperitoneal injection of opioid drugs on response-induced by intra-amygdala [intra-Amyg] microinjection of cannabinoid agents in rats, using elevated plus-maze test of anxiety. Intraperitoneal injection of morphine [3, 6 and 9 mg/kg] increased%OAT and%OAE, but not locomotor activity, showing an anxiolytic response. However, some doses of the opioid receptor antagonist, naloxone reduced%OAT and locomotor activity as well. Intra-Amyg administration of CB1 cannabinoid receptor agonist, ACPA [at the dose of 1.25 and 5 ng/rat] increased%OAT and%OAE but not locomotor activity, thus showing an anxiolytic response, which was increased by morphine [6 mg/kg, i.p.] without any interaction. Naloxone also reduced ACPA effects. Intra-Amyg administration of CB1 cannabinoid receptor antagonist, AM251 [2.5, 25 and 100 ng/rat] did not alter%OAT and%OAE but higher doses of drug [25 and 100 ng/rat] reduced locomotor activity. However, the drug in combination of morphine anxiolytic response and with naloxone decreased anxiety. The results may indicate an anxiolytic for CB1 cannabinoid. Our results also showed that opioid system may have interaction with cannabinoid receptor in the amygdale