Testosterone replacement does not normalize carcass composition in chronically decerebrate male rats

Abstract

Chronically decerebrate (CD) rats, in which the forebrain and its descending projections are completely neurally isolated from hindbrain and rostral projections, gain substantial amounts of body fat, lose lean tissue, and have low circulating testosterone concentrations. We tested whether testosterone replacement would normalize body composition of male CD rats. Five groups of rats were used: CD placebo, CD testosterone, control placebo, castrate placebo, and castrate testosterone. Testosterone replacement was initiated at the first stage of CD surgery in both CDs and castrate controls. The second stage of CD surgery occurred 8 days later, and the study ended 15 days later. Testosterone implants produced 10-fold normal circulating concentrations. Food intake was fixed for all rats by tube feeding. CD rats had substantially more body fat and less lean tissue than neurally intact rats. Testosterone replacement did not affect adiposity of CD rats but did increase carcass water content. Energy expenditure of CD rats was significantly lower than that of control placebo and castrated rats. Testosterone lowered respiratory equivalency ratio and ameliorated a fall in energy expenditure late in the intermeal interval in CD rats. Castration increased, and testosterone decreased luteinizing hormone (LH) and follicle stimulating hormone (FSH) in neurally intact controls. LH was undetectable, and FSH was equivalent to neurally intact controls in CD rats, and neither was affected by testosterone. Collectively, low testosterone did not explain obesity or decreased lean body mass of CD rats, although CD rats exhibited abnormal levels of circulating reproductive hormones and disrupted testosterone negative feedback.

Effect of Crop Protection and Fertilization Regimes Used in Organic and Conventional Production Systems on Feed Composition and Physiological Parameters in Rats

“…36 The same or similar kits were widely used in physiological studies with rats. 18,37,38 Plasma hormone concentrations were analyzed for all rats in each dietary group (= 4 agricultural production systems × 4 field plot replicates × 6 rats = 96 rats). All of the hormone analyses were repeated 2 times per rat plasma sample, and results were expressed in ng/mL (insulin, leptin, GH, corticosterone, and testosterone) or μg/ mL (IGF-1) of plasma.…”

“…The concentration of IgA in blood plasma was measured using a commercially available rat ELISA kit (Bethyl Laboratories, Montgomery, Texas), and plasma concentration of C-reactive protein (CRP) was determined using an ELISA kit designed for the detection and quantification of rat CRP (BD Biosciences, Franklin Lakes, New Jersey) . The same or similar kits were widely used in physiological studies with rats. ,, …”

Feed Composition Differences Resulting from Organic and Conventional Farming Practices Affect Physiological Parameters in Wistar Rats—Results from a Factorial, Two-Generation Dietary Intervention Trial

“…Insulin, leptin, insulin-like growth factor 1 (IGF-1), corticosterone (Cs), and testosterone (Ts) plasma concentrations were measured using radioimmunoassay (RIA) kits (Linco Research, Inc., St. Charles, MO 63304, USA; www.lincoresearch.com). Growth hormone (GH), immunoglobulin A and G (IgA and IgG) plasma concentrations were assessed using enzyme-linked immunosorbent assay (ELISA) kits (Diagnostic Systems Laboratories, Inc., Webster, TX, USA, www.dslabs.com; Bethyl Laboratories, Inc., Montgomery, TX, USA, www.bethyl.com) [70][71][72]. Spleen leukocytes were cultured in vitro for analysis of their proliferation capacity, both spontaneous and mitogen-stimulated; both concanavalin A (ConA, a T-cell specific mitogen, 0.125 µg/well) and lipopolysaccharide (LPS, a B-cell specific mitogen, 2 µg/well) [46] stimulations were used (Sigma-Aldrich Sp, Poznań, Poland, www.sigmaaldrich.com).…”