Protein restriction during lactation alters the autonomic nervous system control on glucose-induced insulin secretion in adult rats

Abstract

Involvement of autonomic nervous system (ANS) neurotransmitters on insulin secretion in rats submitted to protein malnutrition during lactation was studied. During the first 2/3 of lactation, mothers received a 4% protein diet (LP). Control group received normal diet (23% protein) (NP). After protein restriction, mothers received normal diets. At 81 days rats were submitted to intravenous glucose tolerance tests (ivGTT). Plasma glucose and insulin concentration (PIC) were measured. Glucose-induced insulin secretion (GIIS) was tested in pancreatic islets. Fasting normoglycemia and hypoinsulinemia were observed in LP rats. Glucose intolerance and low PIC in LP group were detected during ivGTT. Acetylcholine (Ach) or blockage of alpha-adrenoceptors induced high PIC increment in LP rats; atropine or stimulation of alpha-adrenoceptors did not change PIC. Insulin secretion of LP rat islets showed low glucose and carbachol responses. Epinephrine-inhibited GIIS in both islet groups. Hypoinsulinemia observed in lactation-malnourished rats might be caused by alterations in GIIS regulation, including ANS modulation.

Protein-energy malnutrition at mid-adulthood does not imprint long-term metabolic consequences in male rats

“…In this experimental animal model, these metabolic dysfunctions are implicated in the impairment of autonomic nervous system (ANS) function such as low tonus of vagus nerve and low acetylcholine muscarinic response in pancreatic islets [15,16]. Similar alterations were also observed by others, where ANS disruption was induced by an acute treatment with a low-protein diet in adult rats [17].…”

“…Peripheral insulin resistance, together with obesity proneness, was found when dietary insults were applied during pregnancy as well as at puberty [6,18,24,42]. On the other hand, higher insulin sensitivity in association with a lean phenotype is commonly observed if dietary insult is experienced during the first days of lactation [15,16,25,49]. Additionally, a higher capacity for the pancreatic islets to secret insulin in the former model and a weaker ability of pancreatic islets to secrete insulin in the latter model are characteristics of these metabolic programming models.…”

Intestinal remodelling in mink fed with reduced protein content

“…Maternal protein restriction during gestation and lactation in rats may lead to reduced weight in the offspring. It can be caused by (1) alteration on the control of insulin secretion induced by oscillations of glucose concentration; (2) alteration on the modulation of autonomic nervous system (Gravena et al, 2007);…”

Maternal Caloric Restriction prior to Pregnancy Increases the Body Weight of the Second-Generation Male Offspring and Shortens Their Longevity in Rats

“…Studies agree that lactation is a crucially important period of development where undernourished offspring can acquire a range of components of metabolic syndrome and some damage caused by undernutrition during gestation can be restored (Ozanne and Hales 2004;Benyshek et al 2004Benyshek et al , 2006Pinheiro et al 2008;PeixotoSilva et al 2011). Other studies argue that moderate protein restriction in the early stages of life (during the lactation period) does not cause obesity or related diseases, but is responsible for underweight and hypoinsulinemia (Zambrano et al 2005;Gravena et al 2007;de Oliveira et al 2012). Notwithstanding, with severe restriction, diabetogenic tendencies persist (Pinheiro et al 2008).…”