Estudo estereológico dos efeitos da ayahuasca na neuroanatomia do estriado de sagüis (Callithrix jacchus) em um modelo de depressão

Abstract

The striatum (St) integrates cognitive, motor, and limbic functions and plays a critical role in processing emotions, motivation, and rewards. It may undergo several morphophysiological changes in neuropsychiatric diseases. Depression, a complex psychiatric disorder, affects millions of people around the world and leads to an increased risk of suicide, decreased quality of life, and functional impairment. Conventional treatments require prolonged use, leading to drug resistance; thus, new treatments and therapeutic strategies have been widely studied. Ayahuasca results from the joint infusion of the Banisteriopsis caapi vine and Psychotria viridis leaves, have psychoactive properties, and its use in depression has shown promising results. Our objective was to morphoquantitatively evaluate the effects of Ayahuasca on the St in an already validated model of juvenile depression induced in a non-human primate. Six marmosets were divided into groups of two animals each. One group was kept in family life (FG), and two groups were socially isolated (IG). Isolation was carried out by separating the animal from all others in the colony. One of the isolated groups received doses of ayahuasca tea (TG) 3 days before and two times during the isolation period, while the other groups received the same dose of placebo. After 13 weeks of experimentation, euthanasia, and transcardiac perfusion were performed. The brains were sectioned and stained with thionin using the Nissl method. We evaluated the striatum using stereological techniques to verify the total volume and estimate the total number of neurons and neuronal volume. Equidistant sections of the caudate and putamen were analyzed for all measurements and selected by systematic and uniform sampling. The IG and TG presented increased volumes when compared to the FG. IG showed an increase in the total neuronal number of St in relation to FG. The treatment appears to have controlled this increase. Isolation increased neuronal distribution in the striatum, and Ayahuasca had a reversing effect. Our data show a decrease in the volume of St neurons and Ayahuasca's neuroprotective action in a model of juvenile depression in non-human primates subjected to social isolation, as evidenced by the maintenance of normal neuronal volume and number.