Acute activation of @entity13677 cannabinoid receptors transiently decreases PSA-NCAM expression in the dentate gyrus of the XXXX hippocampus.

@entity10025 @entity13677 @entity14513 @entity1251 @entity35
Recent evidence indicates that the polysialylated neural cell adhesion molecule (PSA-NCAM) is involved in hippocampal plasticity. On the other hand, @entity13677 receptor activation is known to disturb some hippocampal processes involving plastic changes, such as learning and memory. Therefore, the present study investigated the effect of @entity10025 , a @entity13677 receptor agonist, on the expression of PSA-NCAM protein in the dentate gyrus (DG) and @entity1251 region of the @entity35 hippocampus. It was found that at a dose of 0.1 mg/kg i.p. of @entity10025 , the number of PSA-NCAM immunoreactive (IR) cells in the DG declined in a time-dependent manner. The decrease in PSA-NCAM expression was observed at 1 and 2 days (ca. 21% and 30%, respectively), but not after 4 h and 4 days following @entity10025 administration. However, @entity10025 treatment did not change the length density of PSA-NCAM immunopositive processes in @entity1251 mossy fibers at all the time points measured. The effect observed in the DG on day 2 was blocked by @entity14513 (1 mg/kg, i.p.), a @entity13677 receptor antagonist, given 30 min before @entity10025 . Neither the number of Ki-67 (IR) cells (a marker of proliferation) nor the number of doublecortin-IR cells (a marker of immature neurons) was affected by @entity10025 (0.1 mg/kg, i.p.) treatment at any of the time points. An analysis of co-localization of @entity13677 receptor protein with PSA-NCAM protein revealed that both proteins were not present in the same population of neurons in the subgranular layer of the DG. The observed changes in PSA-NCAM expression were not related to the reduction of proliferation or differentiation of newly born cells, but were possible due to alternations in the synaptic activity in the DG. However, such alteration in the PSA-NCAM expression may change the timing of the functional maturation of newly born neurons. Moreover, the above finding suggests that acute activation of @entity13677 receptors may result in the stiffening of the hippocampal structure and susceptibility to plastic changes and may lead to functional impairment governed by alterations in the hippocampal structure.
