Ciência Diária » Alzheimer: novo medicamento oral reduz beta-amiloide no cérebro

Alzheimer: novo medicamento oral reduz beta-amiloide no cérebro

Submitted by Ciência Diária on Tuesday, 31 May 201178 Comentários

Mais de 35 milhões de pessoas sofrem de demência e doença de Alzheimer no mundo.

Pesquisadores estadunidenses acabam de demonstrar que a administração oral de um inibidor de protease cisteína, E64d, não apenas reduz o acúmulo de beta-amiloide no cérebro, mas também melhora substancialmente o déficit de memória em modelos animais com a doença de Alzheimer.

“A descoberta é especialmente importante porque o E64d já demonstrou anteriormente ser seguro para uso em seres humanos e por isso acreditamos que o composto tem um forte potencial como nova terapia para a doença de Alzheimer”, afirma Vivian Hook, professor da Universidade da Califórnia em San Diego, nos EUA, envolvida no trabalho.

O aumento nos níveis de beta-amiloide no cérebro está associado ao desenvolvimento da perda da memória e formação da placa amiloide, principais características do Alzheimer. Peptídeos de beta-amiloide são cortados de uma proteína maior, chamada proteína precursora amiloide, por uma “tesoura” enzimática chamada beta-secretase, e então agregados para formar as placas nas regiões do cérebro responsáveis pela memória.

O E64d reduziu o beta-amiloide pela inibição das “tesouras” beta-secretase – impedindo de cortar a cadeia em pedaços tóxicos menores -, mas os pesquisadores também descobriram que o composto, na verdade, aumenta a atividade de uma protease denominada BACE1, que até então tem sido considerado como a beta-secretase principal. Além disso, o E64d parece diminuir o beta-amiloide no cérebro inibindo a atividade da beta-secretase em outra protease, a catepsina-b.

“O estudo indica a catepsina B como um novo alvo terapêutico para a inibição da produção de beta-amiloide e melhora da memória”, diz Hook. “Esta é uma importante descoberta porque vamos mostrar que a inibição da beta-secretase pode ocorrer com a inibição da catepsina B e sem a inibição da BACE1”.

Veja também:

- Pacientes com câncer tendem a sofrer menos de Alzheimer e vice-versa
- Uso prolongado de celular pode beneficiar memória e reverter efeitos do Alzheimer
- Receptor ajuda sistema de proteção a expulsar “soldados” do Alzheimer
- Personalidade e envelhecimento cerebral dão pistas sobre demência
- Molécula regenera lesões do cérebro em modelos de Alzheimer
- Novo teste promete diagnóstico precoce e preciso do Alzheimer
- Alzheimer: pesquisadores mostram como função de astrócitos é afetada
- Pesquisadores mostram que maconha é ineficaz contra o Alzheimer
- Sonolência diurna e falta de atenção podem indicar Alzheimer

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