Prenatally compromised neurons respond to brain-derived neurotrophic factor treatment in vitro Todd A. Briscoe, Mary Tolcos, Sandra Dieni, Michelle Loeliger and Sandra M. Rees Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia Correspondence and requests for reprints to Associate Professor Sandra M. Rees PhD, Department of Anatomy and Cell Biology, University of Melbourne, Grattan St, Parkville,Victoria 3010, Australia Tel: + 613 8344 5797; fax: + 613 9347 5219; e-mail: s.rees@unimelb.edu.au There were no con£icts of interest associated with this study. Sponsorship: This work was supported by the National Health and Medical Research Council (Australia). Received 28 May 2006; revised 19 June 2006; accepted 20 June 2006 Prenatal hypoxia a¡ects neuronal survival and process outgrowth. Brain-derived neurotrophic factor, which in£uences neural growth, is decreased in these conditions. We tested whether addition of brain-derived neurotrophic factor enhances growth of neurons cultured from guinea pig fetuses ( n¼7) compromised by chronic placental insu⁄ciency from 30^52 days gestation (term B67 days). Cultures were prepared from the olfactory bulb, hippocampus and cerebellum. Compared with controls ( n¼7), chronic placental insu⁄ciency resulted in reduced total neurite length in olfactory bulb cultures. Brain-derived neurotrophic factor treatment for 5 days increased the total olfactory neurite length and somal size and number of primary neurites in all cultures from both control and compromised animals. Thus, brain-derived neurotrophic factor can in£uence the growth of compromised fetal neurons supporting its therapeutic use following chronic placental insu⁄ciency. NeuroReport 17:1385^1389  c 2006 Lippincott Williams & Wilkins. Keywords: brain-derived neurotrophic factor, cell culture, chronic placental insu⁄ciency, intrauterine growth restriction, prenatal hypoxia Introduction Adverse intrauterine conditions during human pregnancy have been shown to cause abnormal brain development and may contribute to the manifestation of neurological dis- orders that develop in later life including cerebral palsy [1], general cognitive and learning deficits [2] and schizophrenia [3]. The specific mechanisms underlying altered structural and functional development are still being elucidated. Our laboratory uses an established guinea pig model of chronic placental insufficiency [4], which mimics a situation that can occur in pregnant women, albeit at the more severe end of the spectrum. The guinea pig, which has a relatively long gestation, was chosen as it undergoes critical maturational events in utero as does the human. The fetuses are chronically hypoxic, are hypoglycemic, have altered endo- crine and growth factor levels [5] and are growth restricted [4]. We have shown that chronic placental insufficiency has significant effects on the development of the central nervous system causing neuronal loss [6] and reductions in axonal and dendritic growth and synaptogenesis [7–9]; several of these deficits persist in the long term [9]. Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, promotes growth and reduces cell death in a number of different neuronal populations such as cerebellar [10] and hippocampal cells [11]; increases in the level of BDNF expression in the brain normally coincide with periods of significant neural development. We have shown that BDNF protein levels are reduced in the central nervous system of growth-restricted guinea pig fetuses [5,12] and therefore might contribute to the altered growth that we have seen in this model [6,7]. Before trialing BDNF therapy in vivo, we wished to determine the effects of exogenous BDNF on primary cell cultures from prenatally compromised fetuses in order to specifically study the effects of the neurotrophin without complication from other sources. Thus, in this study our aim has been firstly to determine the effects of chronic placental insufficiency on the morphology of cultured neurons and secondly to determine the effects of exogenously applied BDNF on neurite outgrowth, specifically in prenatally compromised neurons. Cultures were prepared from the olfactory bulb, cerebellum and hippocampus from control and growth-restricted fetuses as neurons in these regions express BDNF and its cognate receptor, tyrosine kinase B (TrkB), at least in vivo [13] and are known to be affected by chronic placental insufficiency [6,8]. Materials and methods Experimental protocol The following studies were carried out in accordance with the Australian Code of Practice for the Care and Use of DEVELOPMENTAL NEUROSCIENCE NEUROREPORT 0959-4965  c Lippincott Williams & Wilkins Vol 17 No 13 18 September 2006 1385 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.