275. The endocrine disruptor, bisphenol A, alters gene expression in the hypothalamus of the ram lamb but does not alter LH secretion
C. J. Scott A , I. J. Clarke B , J. Wilkins A , T. Flatscher-Bader C , G. B. Martin D and A. J. Tilbrook BA E H Graham Centre for Agricultural Innovation (NSW DPI & Charles Sturt Universit, Wagga Wagga, NSW, Australia.
B Physiology, Monash University, Monash University, Vic., Australia.
C Animal Studies, University of Queensland, St Lucia, Qld, Australia.
D Animal Biology, University of Western Australia, Crawley, WA, Australia.
Reproduction, Fertility and Development 20(9) 75-75 https://doi.org/10.1071/SRB08Abs275
Published: 28 August 2008
Abstract
Bisphenol A (BPA) is an endocrine disruptor, which has both oestrogenic and anti-oestrogenic actions. It has profound effects on development, especially of sex organs but also on the brain. The actions on the brain are poorly understood and little is known about males. Most work has been conducted in fish & rodents, but the lifespan of domestic ruminants means that BPA may accumulate in tissues over many years. This study tested the hypothesis that treatment of ram lambs with BPA would alter LH secretion as well as gene activity in various hypothalamic regions. Ram lambs were treated from 1 month old with thrice weekly injections (im) of BPA (3.5 mg/kg) or vehicle (n = 10/group) for 80days. Weekly bodyweights and jugular blood samples were collected and on day 79, blood samples were taken every 15 min for 8 h for LH RIA. The sheep were killed, body & testicular weights collected and the hypothalamus dissected into anterior, dorsal and ventral blocks, then frozen in liquid nitrogen. Bodyweight (Cont. 26.0 ± 0.5 kg v. BPA 25.2 ± 0.7 kg) and paired testicular weight (Cont. 31.6 ± 1.2 g v. BPA 29.3 ± 1.4 g) did not significantly differ (P > 0.05). LH secretion also did not differ, in either mean LH concentrations (Cont 0.31 ± 0.14 v. BPA 0.29 ± 0.12ng/mL) or pulses/8 h (Cont 1.8 ± 0.4 v. BPA 2.0 ± 0.4). Total RNA was extracted from the basal hypothalamus (ventral block) and RNA from 2 treated and 2 control animals was hybridised on 44K Agilent bovine microarrays. Preliminary analysis suggests 118 probes were differentially expressed. Gene ontology analysis of these differentially expressed probes revealed involvement in a broad range of biological processes and cellular components. This study suggests that gene array analysis is a suitable tool with which to study BPA actions in the sheep hypothalamus. Future work will expand this pilot microarray study to include all animals and all hypothalamic regions.
