EFFECT OF DIFFERENT DOSES OF OLANZAPINE ON MICE’S BONE TISSUE Vitor Caiaffo 1* , Roger Rafael Cavalcanti Bandeira de Melo 2 , Cassia Regina Oliveira Santos 3 , Belisa Duarte Ribeiro de Oliveira 4 , Adelmar Afonso Amorim Junior 5 , Valdemiro Amaro da Silva Junior 6 and Marleyne José Afonso Acioly Lins de Amorim 7 1* Corresponding Autor: Caiaffo, V., Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil. Email: vcaiaffo@gmail.com 2 Department of Veterinary Medicine, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil Email: rogervet@hotmail.com 3 Department of Veterinary Medicine, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil Email: cassiareginavet@hotmail.com 4 Department of Physiotherapy, Caruaruense Associated of High Education, Caruaru, Pernambuco, Brazil Email: belisaduarte@gmail.com 5 Department of Anatomy, Federal University of Pernambuco, Recife, Pernambuco, Brazil Email: adelmarjr@yahoo.com 6 Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil Email: valdemiroamaro@gmail.com 7 Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil Email: mjaamorim@yahoo.com Summary It has been a growing interest in side effects produced by the use of drugs that act on brain neurotransmit ters such as serotonin, dopamine and norepinephrine. This study investigated the effect of olanzapine on mice’s bone tissue. Fifteen (15) male adult mice were divided into three groups: Control (n = 5) without experimental dose, Group 1 (n = 5) with a dose of 15mg/Kg olanzapine and Group 2 (n = 5) with 20mg/kg of olanzapine. Group 2 had reduced body weight from the seventh day of treatment. Both Group 1 (p = 0.013) and group 2 (p <0.0001) showed a reduction in the tibia weight. The length and thickness of proximal and distal epiphyses showed no statistical differences. The thickness of diaphysis was lower in group 2 (p = 0.0025) when comparing to the control, and when comparing the experimental groups, group 2 also showed a reduction in thickness (p = 0.0259). The microscopic analysis showed no change in cortical thickness of diaphysis; however, the number of osteocytes in the epiphysis of group 2 was lower (p = 0.0461). It was noted that the dose of 20 mg/kg showed significant differences in body and bones development of animals analyzed, in particular due to the lethargic state caused by the drug, reducing the ingestion of food and water and preventing their development. Key words: Olanzapine, Atypical antipsychotics, Bone tissue, Tibia. http://pharmacologyonline.silae.it ISSN: 18278620 August 30, 2012 Archives • 2012 • vol.2 • 104 - 111 harmacologyOnLine