RESUMO
We previously developed Cdh23 mutant mice (erl mice) as a model of hearing loss for otoprotective drug evaluation and showed that the erl mutation leads to hearing loss related to endoplasmic reticulum (ER) stress-induced cochlear hair cell apoptosis. Small molecular chemical chaperones, 4-phenylbutyrate (4PBA), targeting ER stress exert a neuroprotective effect. To evaluate whether 4PBA exerts an otoprotective effect, we intraperitoneally injected erl mice with 4PBA daily from postnatal age day 7 up to 12 weeks. Our results showed that treatment with 4PBA significantly alleviated hearing loss and suppressed hair cell death in erl mice. In addition, ER stress-related proteins were downregulated by 4PBA treatment. Our study showed that 4PBA exerts an otoprotective effect, which provides the potential to repurpose the drug for otoprotection.
Assuntos
Caderinas/genética , Células Ciliadas Auditivas/efeitos dos fármacos , Perda Auditiva/tratamento farmacológico , Fenilbutiratos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Morte Celular/efeitos dos fármacos , Morte Celular/genética , Surdez/tratamento farmacológico , Surdez/genética , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Chaperonas Moleculares/genética , Mutação/genéticaRESUMO
Although ample evidence has shown that acute stress impairs memory, the influences of acute stress on different phases of memory, such as acquisition, consolidation and retrieval, are different. Experimental data from both human and animals support that endogenous opioid system plays a role in stress, as endogenous opioid release is increased and opioid receptors are activated during stress experience. On the other hand, endogenous opioid system mediates learning and memory. The aim of the present study was to investigate the effect of acute forced swimming stress on recognition memory of C57 mice and the role of opioid receptors in this process by using a three-day pattern of new object recognition task. The results showed that 15-min acute forced swimming damaged the retrieval of recognition memory, but had no effect on acquisition and consolidation of recognition memory. No significant change of object recognition memory was found in mice that were given naloxone, an opioid receptor antagonist, by intraperitoneal injection. But intraperitoneal injection of naloxone before forced swimming stress could inhibit the impairment of recognition memory retrieval caused by forced swimming stress. The results of real-time PCR showed that acute forced swimming decreased the µ opioid receptor mRNA levels in whole brain and hippocampus, while the injection of naloxone before stress could reverse this change. These results suggest that acute stress may impair recognition memory retrieval via opioid receptors.
