Research Article Acute Effects of Exogenous Hormone Administration on Postprandial Acylation Stimulating Protein Levels in Ovariectomized Rats after a Fat Load Bashair Al Riyami, 1 Marah El-Tahir, 2 Sultan Al Maskari, 1 Eugene H. Johnson, 3 and Jumana Saleh 1 1 Department of Biochemistry, College of Medicine, Sultan Qaboos University, Al-Khod, 123 Muscat, Oman 2 Department of Microbiology and Immunology, College of Medicine, Sultan Qaboos University, Al-Khod, 123 Muscat, Oman 3 Department of Animal and Veterinary Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod, 123 Muscat, Oman Correspondence should be addressed to Jumana Saleh; jumanasaleh@hotmail.com Received 30 June 2014; Accepted 14 November 2014; Published 2 December 2014 Academic Editor: Duo Li Copyright © 2014 Bashair Al Riyami et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. ASP, a potent lipogenic factor, was linked to female fat metabolism in association studies. Aim. To investigate acute efects of sex hormone treatment on postprandial ASP levels in vivo. Methods. 24 female rats were randomly divided into 4 groups including controls. he rats were ovariectomized and injected with progesterone, estrogen, or testosterone. An hour later, olive oil was administered orally. Plasma ASP and triglycerides were measured at several postprandial time points. Area under the curve (TG-AUC) represented TG clearance. Results. Only the progesterone treated group had a signiicant postprandial ASP increase at two hours compared to basal levels (439.8 ± 62.4 versus 253.4 ± 59.03 g/mL,  = 0.04). Interestingly, increased ASP levels coordinated negatively with corresponding TG levels and TG-AUC postprandially, mostly evident in the opposite efects in the progesterone and testosterone treated groups. ASP levels increased 3-fold in the progesterone versus testosterone treated groups, whereas TG-AUC was signiicantly lower. Conclusion. hese indings suggest that progesterone enhances ASP production and TG clearance simultaneously, supporting the notion of a stimulatory role for progesterone on ASP-mediated TG clearance. his is the irst functional study demonstrating a cause-efect relationship between hormone treatment and ASP levels in vivo and may contribute to understanding the mechanism of progesterone function as a female lipogenic hormone. 1. Introduction Acylation stimulating protein (ASP) is a small basic protein that consists of 76-amino acids produced from adipocytes. ASP is produced by the interaction of complement C3, factor B, and adipsin produced in adipose tissue [1]. Despite numer- ous identiied adipose tissue derived factors, ASP uniquely demonstrated a great efect in lipogenesis stimulation. ASP actively stimulates TG synthesis in human ibroblasts and to a much greater extent in adipocytes [2]. his occurs through the enhanced esteriication of fatty acids in adipose tissue by increasing the activity of diacylglycerol acyltrans- ferase (DGAT), the rate limiting enzyme in TG synthesis, and indirectly enhances the activity of lipoprotein lipase (LPL) in adipocytes by increasing fatty acid trapping within adipocytes [3]. ASP was also found to inhibit hormone- sensitive lipase (HSL) [4]. Interestingly, ASP was shown to be as potent as insulin in its fat storage efects. However, ASP efects were independent, and additive, to insulin. Dietary triglyceride rich lipoproteins, chylomicrons (CHYLO) were the most potent stimulators of ASP production in vitro [5]. In animal studies, using a C3 knockout (ASP deicient) mice showed delayed postprandial TG clearance and reduced TG storage capacity ater a fat load [2, 6], which highlighted the important role of ASP in the postprandial TG clearance. Such an efect was diminished by the administration of Hindawi Publishing Corporation Journal of Nutrition and Metabolism Volume 2014, Article ID 510916, 7 pages http://dx.doi.org/10.1155/2014/510916