Abstract An emerging area in schizophrenia research focuses on the impact of immunomodulatory drugs such as melatonin, which have played important roles in many biological systems and functions, and appears to be promising. The objective was to evaluate the effect of melatonin on behavioral parameters in an animal model of schizophrenia. For this, Wistar rats were divided and used in two different protocols. In the prevention protocol, the animals received 1 or 10mg/kg of melatonin or water for 14 days, and between the 8th and 14th day they received ketamine or saline. In the reversal protocol, the opposite occurred. On the 14th day, the animals underwent behavioral tests: locomotor activity and prepulse inhibition task. In both protocols, the results revealed that ketamine had effects on locomotor activity and prepulse inhibition, confirming the validity of ketamine construction as a good animal model of schizophrenia. However, at least at the doses used, melatonin was not able to reverse/prevent ketamine damage. More studies are necessary to evaluate the role of melatonin as an adjuvant treatment in psychiatric disorders.

RESUMONovos estudos sugerem que os ácidos graxos poliinsaturados, como o ômega-3, podem reduzir os sintomas da esquizofrenia. O presente estudo avaliou o efeito preventivo do ômega-3 sobre os níveis de interleucinas (IL) e o fator neurotrófico derivado do cérebro (BDNF) em cérebros de ratos jovens submetidos a um modelo de esquizofrenia. O tratamento foi feito por 21 dias, iniciando no 30º dia de vida dos animais. Depois de 14 dias de tratamento com ômega-3 ou veículo, um tratamento concomitante com salina ou ketamina (25 mg/kg) foi iniciado e mantido até o último dia do experimento. No cortex pré-frontal dos ratos, os níveis de BDNF diminuíram em 1 h e 24 h depois da última administração de ketamina enquanto que o grupo administrado com ketamina e ômega-3 mostrou uma diminuição nos níveis de BDNF somente após as 24 h. Em contraste, ambas as intervenções induziram respostas similares quanto aos níveis de IL-1β e IL6. Esses achados sugerem que a similaridade nos níveis de IL-1β e IL6 em nossos grupos de experimento é devida ao mecanismo de ação da ketamina sobre o sistema imune. Mais estudos são necessários para explicar essa patologia. Em conclusão, de acordo com estudos prévios e considerando o atual estudo, nós sugerimos que o ômega-3 tem um papel profilático no desenvolvimento de sintomas associados à esquizofrenia.

ABSTRACTNew studies suggest that polyunsaturated fatty acids, such as omega-3, may reduce the symptoms of schizophrenia. The present study evaluated the preventive effect of omega-3 on interleukines (IL) and neurotrophin brain-derived neurotrophic factor (BDNF) levels in the brains of young rats subjected to a model of schizophrenia. Treatment was performed over 21 days, starting on the 30th day of rat's life. After 14 days of treatment with omega-3 or vehicle, a concomitant treatment with saline or ketamine (25 mg/kg) was started and maintained until the last day of the experiment. BDNF levels in the rat's prefrontal cortex were decreased at 1 h and 24 h after the last administration of ketamine, whereas the group administered with ketamine and omega-3 showed a decrease in BDNF levels only after 24 h. In contrast, both interventions induced similar responses in levels of IL-1β and IL6. These findings suggest that the similarity of IL-1β and IL6 levels in our experimental groups is due to the mechanism of action of ketamine on the immune system. More studies have to be carried out to explain this pathology. In conclusion, according to previous studies and considering the current study, we could suggest a prophylactic role of omega-3 against the outcome of symptoms associated with schizophrenia.

O presente trabalho foi realizado em um remanescente de Floresta Estacional Semidecidual antropizado, localizada nas coordenadas 29° 49'S e 52° 25'W, nas proximidades do pólo petroquímico no município de Montenegro (RS), Brasil, com o objetivo de conhecer seus aspectos florísticos e fitossociológicos. A amostragem foi sistemática constituída de 21 faixas com 10m de largura e comprimento variável de acordo com a extensão da floresta, distantes entre si em 80m, onde foram distribuídas parcelas contíguas de 10 x 10m (100m²). Foram avaliados indivíduos que apresentavam circunferência à altura do peito (CAP)>15cm, totalizando 3.854 indivíduos (1,83ha), distribuídos em 81 espécies, 59 gêneros e 32 famílias. As famílias botânicas mais representativas na formação foram Myrtaceae (13 espécies), Fabaceae (7), Lauraceae (6), Meliaceae (5), Moraceae e Euphorbiaceae (4). As espécies mais características e importantes da floresta foram Sebastiania commersoniana, Casearia sylvestris, Myrsine umbellata, Mimosa bimucronata, Allophylus edulis e Syagrus romanzoffiana, representando 51,52 % do VI. A floresta apresentou média diversidade, com índice de Shannon de 1,9948 (nats.), indicando antropismo.

This research was developed in a Semideciduous Seasonal Forest located at coordinates (29° 49'S; 52° 25'W) in Montenegro Petrochemical pole, Rio Grande do Sul, Brazil, aiming at studying the floristic and phytossociological aspects of the forest. Sampling was systematic and composed of 21 strips (10m wide and variable length according to fragment extension located 80m apart. In the strips the distribution was in contiguous 10 X 10m plots (100m²). Individuals that presented circumference at breast height (CBH)>15cm, totaling 3.854 individuals (1,83ha), distributed in 81 species, 59 geneus and 32 families were appraised. The most representative botanic families in the forest formation were Myrtaceae (13 species); Fabaceae (7), Lauraceae (6); Meliaceae (5), Moraceae and Euphorbiaceae (4). The most valuable species were Sebastiania commersoniana, Casearia sylvestris, Myrsine umbellata, Mimosa bimucronata, Allophylus edulis e Syagrus romanzoffiana, representing 51.52 % of IV. The forest had been presented low diversity with Shannon index of 1.9948 (nats/individuals), indicating human impact.