Acute injection of ASP in the third ventricle inhibits food intake and locomotor activity in rats

Abstract

ing protein (ASP; also known as C3adesArg) stimulates triglyceride synthesis and glucose transport via interaction with its receptor C5L2, which is expressed peripherally (adipose tissue, muscle) and centrally. Previous studies have shown that ASP-deficient mice (C3KO) and C5L2-deficient mice (C5L2KO) are hyperphagic (59 to 229% increase, P Ͻ 0.0001), which is counterbalanced by increased energy expenditure measured as oxygen consumption (V O2) and a lower RQ. The aim of the present study was to evaluate ASP's effect on food intake, energy expenditure, and neuropeptide expression. Male rats were surgically implanted with intracerebroventricular (icv) cannulas directed toward the third ventricle. After a 5-h fast, rats were injected, and food intake was assessed at 0.5, 1, 2, 4, 16, 24, and 48 h, with a 5-to 7-day washout period between each injection. Acute icv injections of ASP (0.3-1,065 pmol) had a time-dependent effect on decreasing food intake by 20 to 57% (P Ͻ 0.05). Decreases were detected by 30 min (maximum 57%, P Ͻ 0.01) and at the highest dose effects extended to 48 h (19%, P Ͻ 0.05, 24-to 48-h period). Daily body weight gain was decreased by 131% over the first 24 h and 29% over the second 24 h (P Ͻ 0.05). A conditioned taste aversion test indicated that there was no malaise. Furthermore, acute ASP injection affected energy substrate usage, demonstrated by decreased V O2 and RQ (P Ͻ 0.05; implicating greater fatty acid usage), with a 49% decrease in total activity over 24 h (P Ͻ 0.05). ASP administration also increased anorexic neuropeptide POMC expression (44%) in the arcuate nucleus, with no change in NPY. Altogether ASP may have central in addition to peripheral effects. acylation-stimulating protein; C5L2; energy metabolism; proopiomelanocortin IN RECENT YEARS, MUCH ATTENTION HAS FOCUSED on the hypothalamic-adipose axis (46). White adipose tissue (WAT), recognized originally for its capacity to store excess dietary energy in the form of triglycerides (TG), is now considered an endocrine organ because of its capacity to secrete hormones and cytokines (17). WAT is now recognized as a fundamental participant in the control of energy metabolism (22). The number of adipokines has expanded rapidly, and these include leptin, adiponectin, resistin, acylation-stimulating protein (ASP), and many more (17). The role of ASP and its involvement in the control of energy balance and in the development of obesity have been actively studied in our group for the last decade.ASP promotes TG synthesis in WAT through interaction with its cell surface receptor C5L2. Activation and phosphorylation of C5L2 leads to increased fatty acid uptake, increased glucose transport, and stimulation of diacylglycerol acyltransferase activity (9,10,19,20). ASP is produced through cleavage of the precursor protein complement C3 via factor B and adipsin (factor D) interaction generating C3a, which is rapidly desarginated to produce ASP (also known as C3adesArg) (6, 25). C3-knockout mice (C3 Ϫ/Ϫ ; also known as C3KO) are deficient in AS...

Recombinant Acylation Stimulating Protein Administration to C3−/− Mice Increases Insulin Resistance via Adipocyte Inflammatory Mechanisms

“…Recombinant human ASP (rASP) was produced and purified as previously described in detail; including sequential extraction, Ni 2+ sepharose binding and HPLC reverse-phase chromatography [33] [20], [52]. Detailed characterization is provided elsewhere [20], however, HPLC-purified ASP preparations used in injections were >98% pure based on mass spectrometry, and were C5a, insulin and endotoxin negative.…”

C5L2: a controversial receptor of complement anaphylatoxin, C5a

“…Both C5L2 and C5aR are present in the anterior pituitary gland, and C5a was demonstrated to stimulate adrenocorticotropic hormone release; however, whether this effect is through C5aR or C5L2 is unclear (55). In addition, administration of ASP into the third ventricle promotes an anorexigenic state through modulation of neuropeptide Y and proopiomelanocortin expression (56).…”

LGR4 and Its Ligands, R-Spondin 1 and R-Spondin 3, Regulate Food Intake in the Hypothalamus of Male Rats

“…Saccharin (0.15% wt/vol) was used as the conditioned stimulus and lithium chloride (LiCl) (0.60M, 1% body weight, injected ip) as the malaiseinducing agent (25). Conditioned taste aversion test were done according to the protocol described by Roy et al (26). Briefly, for 6 days before the onset of the experiment, rats were restricted to 60-minute water access daily until water intake stabilized.…”