Determining insulin sensitivity from glucose tolerance tests in Iberian and landrace pigs

José Miguel Rodríguez-López; Manuel Lachica; Lucrecia González-Valero; Ignacio Fernández-Fígares

doi:10.7717/peerj.11014

Determining insulin sensitivity from glucose tolerance tests in Iberian and landrace pigs

PeerJ. 2021 Mar 10:9:e11014. doi: 10.7717/peerj.11014. eCollection 2021.

Authors

José Miguel Rodríguez-López¹, Manuel Lachica², Lucrecia González-Valero², Ignacio Fernández-Fígares²

Affiliations

¹ Départment Sciences Agronomiques et Animales, Institut Polytechnique LaSalle Beauvais, Beauvais, France.
² Department of Physiology and Biochemistry of Animal Nutrition, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain.

Abstract

As insulin sensitivity may help to explain divergences in growth and body composition between native and modern breeds, metabolic responses to glucose infusion were measured using an intra-arterial glucose tolerance test (IAGTT). Iberian (n = 4) and Landrace (n = 5) barrows (47.0 ± 1.2 kg body weight (BW)), fitted with a permanent carotid artery catheter were injected with glucose (500 mg/kg BW) and blood samples collected at -10, 0, 5, 10, 15, 20, 25, 30, 45, 60, 90, 120 and 180 min following glucose infusion. Plasma samples were analysed for insulin, glucose, lactate, triglycerides, cholesterol, creatinine, albumin and urea. Insulin sensitivity indices were calculated and analysed. Mean plasma glucose, creatinine and cholesterol concentrations were lower (P < 0.01) in Iberian (14, 68 and 22%, respectively) than in Landrace pigs during the IAGTT. However, mean plasma insulin, lactate, triglycerides and urea concentrations were greater (P < 0.001) in Iberian (50, 35, 18 and 23%, respectively) than in Landrace pigs. Iberian pigs had larger area under the curve (AUC) of insulin (P < 0.05) or tended to a greater AUC of lactate (P < 0.10), and a smaller (P < 0.05) AUC for glucose 0-60 min compared with Landrace pigs. Indices for estimating insulin sensitivity in fasting conditions indicated improved β-cell function in Iberian compared with Landrace pigs, but no difference (P > 0.10) in calculated insulin sensitivity index was found after IAGTT between breeds. A time response (P < 0.05) was obtained for insulin, glucose and lactate so that maximum concentration was achieved at 10 and 15 min post-infusion for insulin (Iberian and Landrace pigs, respectively), immediately post-infusion for glucose, and 20 min post-infusion for lactate, decreasing thereafter until basal levels. There was no time effect for the rest of metabolites evaluated. In conclusion, growing Iberian pigs challenged with an IAGTT showed changes in biochemical parameters and insulin response that may indicate an early stage of insulin resistance.

Keywords: Fatty pig; Insulin resistance; Lean pig; Metabolism; Obesity.

Grants and funding

This research was supported by grants no. AGL 2006-05937/GAN and AGL 2009-08916 from Ministerio de Educación y Ciencia (Spain) and RECUPERA 2020, FEDER funding). There was no additional external funding received for this study. The publication fee was supported by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.