REPRODUCTION RESEARCH Testicular angiogenic activity in response to food restriction in rabbits M Carvalho, L Mateus 1 , F Afonso 1 , S Van Harten 2 , L Alfaro Cardoso 2 , D A Redmer 3 and G Ferreira-Dias 1 Faculty of Sciences, University of Lisbon, Lisbon, Portugal, 1 CIISA, Faculty of Veterinary Medicine, Technical University of Lisbon (UTL), Lisbon, Portugal, 2 Tropical Research Institute (IICT), Lisbon, Portugal and 3 Department of Animal Sciences, North Dakota State University, Fargo, North Dakota, USA Correspondence should be addressed to G Ferreira-Dias at CIISA, Faculdade de Medicina Veterina ´ria, Avenida da Universidade Te ´cnica, 1300-477 Lisboa, Portugal; Email: gmlfdias@fmv.utl.pt Abstract The objective of this study was to evaluate the effects of two different levels offood restriction on testicular angiogenic activity, microvascularization, tissue growth, and regression, using the rabbit as a study model. The rabbits (Oryctolagus cuniculus cuniculus) were randomly assigned to a control group (A, nZ5), fed ad libitum, and to groups B (nZ5) and C (nZ5), with two different levels of food restriction. Food restriction was responsible for a 21.2% decrease in body weight in group B and 34.7% in group C. Testis explants were cultured for 24 h and conditioned media were tested for their ability to stimulate mitogenesis of bovine aortic endothelial cells (BAEC). There was an increase in testicular microvascular area and mitogenesis of BAEC in group C rabbits. Despite no change in testicular DNA concentration among groups, food restriction decreased both RNA and protein compared with control. No treatment differences in the percentage of seminiferous tubules filled with all stages of spermatogenesis (spermatogonia, spermatocytes, and spermatids) and spermatozoa, as well as the area occupied by seminiferous tubules, were observed. Nevertheless, serum testosterone was markedly less in group C compared with groups A and B. These results suggest that angiogenesis may play a role in overcoming testicular nutritional impairment in rabbits subjected to food restriction. Reproduction (2009) 137 509–515 Introduction Nutrition plays an important role in growth and develop- ment of the reproductive system. Animals often exposed to dramatic climatic changes (periodic draughts) inducing food restriction have developed survival tactics that include cessation of energetically costly processes, such as growth and reproduction (Bronson 1999). Food restriction shifts nutrients away from reproductive function toward somatic cell maintenance (McCarter et al. 1985). Studies in different animal species indicate that dietary restriction can have a positive effect on the delay of several diseases, improving health and extending long- evity, specifically reducing both the incidence and the growth of tumors (Birt et al. 1999, Beecken et al. 2001, Mukherjee et al. 2002, 2004). Alterations in the metabolic, neuroendocrine, and apoptotic processes are also observed, in order to assure the individual’s survival. However, these changes occur differently in specific organ systems (Mukherjee et al. 2002, Koubova & Guarente 2003). Dietary restriction has an effect on testes, leading to a progressive decrease in testicular volume (Thwaites 1995). This decline is more significant as dietary restriction is intensified (Thwaites 1995, Young et al. 2000, Santos et al. 2004). Testicular regression can be mediated by apoptosis, such as in white-footed mice (Young et al. 2000). Mice subjected to food restriction exhibited a decline in testicular and epididymal weights, and reduced serum testosterone levels (Santos et al. 2004). However, in contrast with these findings, rats subjected to a 30% caloric restriction for 8 weeks showed an increase in testicular weight when compared with unrestricted control animals (Gursoy et al. 2001). Angiogenesis, the formation of new blood vessels from the pre-existing vasculature, is a process that, in adults, is a relatively infrequent event. Physiological angiogenesis in the adult is mostly restricted to the female reproductive tract during the ovarian/uterine cycle (Reynolds et al. 1992, Augustin et al. 1995, Ferreira-Dias et al. 2006, Roberto da Costa et al. 2007), and to the male reproductive tract during gonadal recrudescence in seasonal breeders (Mayerhofer et al. 1989). However, neovascularization is also present in adult life in conditions such as tissue repair or regeneration during healing of wounds or fractures, or q 2009 Society for Reproduction and Fertility DOI: 10.1530/REP-08-0199 ISSN 1470–1626 (paper) 1741–7899 (online) Online version via www.reproduction-online.org Downloaded from Bioscientifica.com at 05/06/2020 11:53:38PM via free access