Neck Circumference Is Associated with Muscle Sympathetic Nerve Activity in Overweight and Obese Men but Not Women

Abstract

Background: Neck circumference (NC) is a predictor of cardiometabolic risk. The objective of this study was to explore the relationship of NC to muscle sympathetic nerve activity (MSNA) within an overweight and obese population.Methods: The study design was a retrospective cross-sectional analysis. Un-medicated persons (72 men, 53 postmenopausal women) aged 56 ± 1 years (mean ± SEM) with body mass index (BMI) 32.8 ± 0.4 kg/m2, were studied. NC was measured together with traditional anthropometric measures, supine blood pressure, fasting blood lipids, insulin, and glucose. Insulin sensitivity was assessed by homeostasis model (HOMA-IR) and Matsuda Insulin Sensitivity Index (ISI) derived from 75-g oral glucose tolerance test. Resting multiunit MSNA was recorded by microneurography in the peroneal nerve and expressed as burst frequency and burst incidence.Results: Men within the highest tertile of NC had significantly higher fasting and post-glucose plasma insulin levels (insulin AUC0−120), HOMA-IR, non-esterified fatty acids, MSNA (45 ± 2 vs. 36 ± 2 bursts per min; 69 ± 3 vs. 58 ± 3 bursts per 100 hb) and heart rate, and lower Matsuda ISI compared to men in the lowest tertile (P all <0.05). In stepwise regression analyses, NC alone explained 12%, and together with insulin AUC0−120 it accounted for 22%, of the variance in MSNA in men. In women, NC was associated with anthropometric measures but not with MSNA or metabolic indices.Conclusions: Among overweight and obese men, NC was independently associated with elevated MSNA and hyperinsulinemia, and thus may be relevant to cardiometabolic risk prediction. The biological basis of gender differences merits further elucidation.

Sex differences in the sympathoexcitatory response to insulin in obese rats: role of neuropeptide Y

“…; Straznicky et al . ). We therefore aimed to test whether this sex difference can be explained in part by differences in the central sympathoexcitatory responses to insulin in obese rats.…”

“…; Straznicky et al . ), became far less insulin resistant. Fasting plasma insulin levels were also lower in obese females compared to males.…”

“…Several studies in humans have demonstrated that obesity increases MSNA in men but not women (Lambert et al 2007; Tank et al 2008;Maqbool et al 2010;Brooks et al 2015;Straznicky et al 2017). We therefore aimed to test whether this sex difference can be explained in part by differences in the central sympathoexcitatory responses to insulin in obese rats.…”

“…In men, obesity increases muscle SNA (MSNA). In women, MSNA either does not relate (Lambert et al 2007;Tank et al 2008;Maqbool et al 2010;Brooks et al 2015;Straznicky et al 2017) or relates weakly (Ribeiro et al 2001) to indices of adiposity such as body mass index. One explanation for this sex difference may be that, in females, the sympathoexcitatory effect of leptin varies during the reproductive cycle .…”

“…; Straznicky et al . ) or relates weakly (Ribeiro et al . ) to indices of adiposity such as body mass index.…”