ECTS2016 Poster Presentations Bone biomechanics and quality (21 abstracts)
Sexually dimorphic response on bone development after neonatal thymectomy in rats
Wagner Garcez de Mello 1, , Noélle Egídia Watanabe Kiill 1 , Gisele Mitsui Kayahara 2, , Olívia Borghi Nascimento 2, , Narayana Guimarães Marqui 2, , Marcelo Macedo Crivelini 4 , Mário Jefferson Quirino Louzada 3 , José Antunes-Rodrigues 5 & João Cesar Bedran de Castro 6
1Multicentric Graduate Studies Program in Physiological Sciences, Brazilian Physiological Society/Univ. Estadual Paulista-UNESP, Araçatuba, São Paulo, Brazil; 2Centro Universitário Toledo-UNITOLEDO, Araçatuba, São Paulo, Brazil; 3Department of Support to Production and Health Animal, Araçatuba Veterinary Medicine School, Univ. Estadual Paulista-UNESP, Araçatuba, São Paulo, Brazil; 4Department of Pathology and Clinical Propaedeutic, School of Dentistry, Univ. Estadual Paulista-UNESP, Araçatuba, São Paulo, Brazil; 5Department of Physiology, Ribeirão Preto Medical School, University of São Paulo - USP, Ribeirão Preto, São Paulo, Brazil; 6Department of Basic Sciences, Araçatuba Dental School, Univ. Estadual Paulista-UNESP, Araçatuba, São Paulo, Brazil.
The effects of neonatal thymectomy, at 3 days of age, on skeletal sexual dimorphism and bone quality during the development were examined in male and female Wistar rats. Rats were euthanized at 20, 40, or 120 postnatal days and femurs were collected. The Biomechanical compression test was used to evaluate bone breaking strength, energy-to-fracture, and extrinsic stiffness. During the prepubertal period, the neonatal thymectomy increases extrinsic stiffness of bone tissue significantly (P=0.0243) only in both groups of males. The energy-to-fracture was increased in both groups of females compared with control males, showing the sex influence (P=0.0243) on this variable. The bone breaking strength showed a significant interaction between treatment and sex (P=0.0108), neonatally-thymectomized males were higher than their respective controls and both groups of females groups. At puberty, the treatment was significant (P=0.0108) on the extrinsic stiffness, control females had stiffness greater than only both thymectomized groups. Since the energy-to-fracture was similar in all groups, there were no statistically significant interactions between sex and treatment (P=0.6283). Treatment influenced the bone breaking strength during this period (P<0.0001), for both male and female control were bigger than both thymectomized-groups. In adulthood animals, the extrinsic stiffness showed a significant interaction between sex and treatment (P=0.0003), control females had higher results than males control and neonatally-thymectomized females. The energy-to-fracture was higher in both groups of males compared to the group of neonatally-thymectomized females, and neonatally-thymectomized males still had, higher values than the females control group (P<0.0001). The results showed significant interaction between treatment and sex (P=0.0110) for bone breaking strength, control males and neonatally-thymectomized females showed higher values than the control group females. The results show that neonatal thymectomy during the critical period of life, induce sex- and age-related modification in skeletal development and provide new insight into the dynamic complexity the skeletal sexual dimorphism.
Volume 5
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Bone Abstracts
ISSN 2052-1219 (online)
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