Animal models in obesity and hypertension. Curr Hypertens Rep. 2013;15:190-195. [PMID: 23536127 DOI: 10.1007/s11906-013-0338-3]

Cardiovascular responses to experimental weight gain in humans: a feasibility study

OBJECTIVE

Obesity and hypertension share a well known association. However, the mechanisms underlying their relationship are not well understood. Our goal was to assess the feasibility of a longitudinal, interventional weight gain study with detailed cardiovascular measurements in humans.

METHODS

Sixteen healthy, normotensive, young, male volunteers (28 ± 7 years) were enrolled. Body composition, biochemical and cardiovascular data were obtained at baseline, and after an 8-week period of overfeeding (800-1000 kcal/day). Blood pressure (BP), cardiac output (CO) and peripheral vascular resistance (PVR) were determined, as were the minimum forearm vascular resistance (MFVR), forearm blood flow (FBF) response to mental stress and heart rate variability (HRV) parameters.

RESULTS

Overfeeding resulted in a median weight gain of 5.6 kg [interquartile range (IQR) 4.6-6.4 kg; P  < 0.001]. Seated systolic and diastolic BP were significantly increased by 10 ± 9 and 4 ± 6 mmHg, respectively, after weight gain ( P  < 0.001 and P  = 0.011, respectively). CO also increased and PVR decreased significantly as a result of weight gain ( P  = 0.032 and P  = 0.044, respectively). MFVR was also significantly decreased after weight gain ( P  = 0.023). The FBF response to mental stress was blunted significantly ( P  = 0.002), and sympathovagal balance and responsiveness to orthostatic challenge altered moderately after weight gain.

CONCLUSION

Our overfeeding regimen resulted in moderate weight gain and significant increases in BP. An increase in CO is likely to be the dominant mechanism underlying the observed BP changes, with decreases in PVR partially compensating for these effects. Experimental weight gain, coupled with detailed cardiovascular phenotyping, is a feasible model to examine potential mechanisms underlying obesity-associated hypertension in young adults.

Network pharmacology: curing causal mechanisms instead of treating symptoms

For complex diseases, most drugs are highly ineffective, and the success rate of drug discovery is in constant decline. While low quality, reproducibility issues, and translational irrelevance of most basic and preclinical research have contributed to this, the current organ-centricity of medicine and the 'one disease-one target-one drug' dogma obstruct innovation in the most profound manner. Systems and network medicine and their therapeutic arm, network pharmacology, revolutionize how we define, diagnose, treat, and, ideally, cure diseases. Descriptive disease phenotypes are replaced by endotypes defined by causal, multitarget signaling modules that also explain respective comorbidities. Precise and effective therapeutic intervention is achieved by synergistic multicompound network pharmacology and drug repurposing, obviating the need for drug discovery and speeding up clinical translation.

Network and Systems Medicine: Position Paper of the European Collaboration on Science and Technology Action on Open Multiscale Systems Medicine

Introduction: Network and systems medicine has rapidly evolved over the past decade, thanks to computational and integrative tools, which stem in part from systems biology. However, major challenges and hurdles are still present regarding validation and translation into clinical application and decision making for precision medicine. Methods: In this context, the Collaboration on Science and Technology Action on Open Multiscale Systems Medicine (OpenMultiMed) reviewed the available advanced technologies for multidimensional data generation and integration in an open-science approach as well as key clinical applications of network and systems medicine and the main issues and opportunities for the future. Results: The development of multi-omic approaches as well as new digital tools provides a unique opportunity to explore complex biological systems and networks at different scales. Moreover, the application of findable, applicable, interoperable, and reusable principles and the adoption of standards increases data availability and sharing for multiscale integration and interpretation. These innovations have led to the first clinical applications of network and systems medicine, particularly in the field of personalized therapy and drug dosing. Enlarging network and systems medicine application would now imply to increase patient engagement and health care providers as well as to educate the novel generations of medical doctors and biomedical researchers to shift the current organ- and symptom-based medical concepts toward network- and systems-based ones for more precise diagnoses, interventions, and ideally prevention. Conclusion: In this dynamic setting, the health care system will also have to evolve, if not revolutionize, in terms of organization and management.

Cancer and comorbidity: The role of leptin in breast cancer and associated pathologies

Obesity is an important risk factor for postmenopausal breast cancer and also a poor prognostic factor among cancer patients. Moreover, obesity is associated with a number of health disorders such as insulin resistance/type-2 diabetes mellitus, hypertension, and other cardiovascular diseases. Frequently, these health disorders exhibit as components/complications of the metabolic syndrome. Nevertheless, obesity-related diseases may coexist with postmenopausal breast cancer; and these comorbid conditions could be substantial. Therefore, it may be assumed that different diseases including breast cancer could originate from a common pathological background in excessive adipose tissue. Adipocyte-released hormone-like cytokine (or adipokine) leptin behaves differently in a normal healthy state and obesity. A growing body of evidence suggests an important role of leptin in our major obesity-related health issues such as insulin resistance, hypertension, and neoplasia. In this context, this review describes the relationships of the abovementioned pathologies with leptin.

Nesfatin-1: functions and physiology of a novel regulatory peptide

Nesfatin-1 was identified in 2006 as a potent anorexigenic peptide involved in the regulation of homeostatic feeding. It is processed from the precursor-peptide NEFA/nucleobindin 2 (NUCB2), which is expressed both in the central nervous system as well as in the periphery, from where it can access the brain via non-saturable transmembrane diffusion. In hypothalamus and brainstem, nesfatin-1 recruits the oxytocin, the melancortin and other systems to relay its anorexigenic properties. NUCB2/nesfatin-1 peptide expression in reward-related areas suggests that nesfatin-1 might also be involved in hedonic feeding. Besides its initially discovered anorexigenic properties, over the last years, other important functions of nesfatin-1 have been discovered, many of them related to energy homeostasis, e.g. energy expenditure and glucose homeostasis. Nesfatin-1 is not only affecting these physiological processes but also the alterations of the metabolic state (e.g. fat mass, glycemic state) have an impact on the synthesis and release of NUCB2 and/or nesfatin-1. Furthermore, nesfatin-1 exerts pleiotropic actions at the level of cardiovascular and digestive systems, as well as plays a role in stress response, behavior, sleep and reproduction. Despite the recent advances in nesfatin-1 research, a putative receptor has not been identified and furthermore potentially distinct functions of nesfatin-1 and its precursor NUCB2 have not been dissected yet. To tackle these open questions will be the major objectives of future research to broaden our knowledge on NUCB2/nesfatin-1.

The prothrombotic state associated with obesity-induced hypertension is reduced by cocoa and its main flavanols

Cocoa flavanols could ameliorate cardiovascular health in obese patients.

Hypertension in children with obesity

The prevalence of obesity related hypertension has dramatically increased in children with the parallel increase in pediatric obesity. This pediatric health problem may adversely affect cardiovascular health in adult life. The pathogenesis of hypertension in obese children is not widely understood. We therefore undertake this review to raise public awareness. Early childhood parameters like birth weight and postnatal weight gain may play important roles in risk for obesity and obesity related hypertension later in childhood and adult life. Further information is required to confirm this origin of hypertension so that appropriate measures are taken in the peri-natal period. The role of sympathetic nervous system has now been well established as one of the principle mechanisms involved in obesity related hypertension. The Renin-Angiotensin system, insulin resistance due to obesity and as a part of metabolic syndrome along with imbalance in adipokines such as leptin and adiponectin, cause activation of the sympathetic system, vasoconstriction, endothelial dysfunction and sodium reabsorption among other perturbations. Multi-step interventions targeting these various mechanisms are required to break the cycle of obesity and metabolic syndrome. Vitamin D deficiency, sleep apnea due to airway obstruction and hyperuricemia may also play a significant role and should not be ignored in its early stages. Obesity is a risk factor for other co-morbid conditions like chronic kidney disease and fatty liver which further accentuate the risk of hypertension. Increased awareness is required to prevent, diagnose and treat obesity related hypertension among the pediatric population.

Neural circuitry underlying the central hypertensive action of nesfatin-1: melanocortins, corticotropin-releasing hormone, and oxytocin

Nesfatin-1 is produced in the periphery and in the brain where it has been demonstrated to regulate appetite, stress hormone secretion, and cardiovascular function. The anorexigenic action of central nesfatin-1 requires recruitment of neurons producing the melanocortins and centrally projecting oxytocin (OT) and corticotropin-releasing hormone (CRH) neurons. We previously have shown that two components of this pathway, the central melanocortin and oxytocin systems, contribute to the hypertensive action of nesfatin-1 as well. We hypothesized that the cardiovascular effect of nesfatin-1 also was dependent on activation of neurons expressing CRH receptors, and that the order of activation of the melanocortin-CRH-oxytocin circuit was preserved for both the anorexigenic and hypertensive actions of the peptide. Pretreatment of male rats with the CRH-2 receptor antagonist astressin2B abrogated nesfatin-1-induced increases in mean arterial pressure (MAP). Furthermore, the hypertensive action of CRH was blocked by pretreatment with an oxytocin receptor antagonist ornithine vasotocin (OVT), indicating that the hypertensive effect of nesfatin-1 may require activation of oxytocinergic (OTergic) neurons in addition to recruitment of CRH neurons. Interestingly, we found that the hypertensive effect of α-melanocyte stimulating hormone (α-MSH) itself was not blocked by either astressin2B or OVT. These data suggest that while α-MSH-producing neurons are part of a core melanocortin-CRH-oxytocin circuit regulating food intake, and a subpopulation of melanocortin neurons activated by nesfatin-1 do mediate the hypertensive action of the peptide, α-MSH can signal independently from this circuit to increase MAP.

Adipose afferent reflex: sympathetic activation and obesity hypertension

Excessive sympathetic activity contributes to the pathogenesis of hypertension and the progression of the related organ damage. Adipose afferent reflex (AAR) is a sympatho-excitatory reflex that the afferent activity from white adipose tissue (WAT) increases sympathetic outflow and blood pressure. Hypothalamic paraventricular nucleus (PVN or PVH) is one of the central sites in the control of the AAR, and ionotropic glutamate receptors in the nucleus mediate the AAR. The AAR is enhanced in obesity and obesity hypertension. Enhanced WAT afferent activity and AAR contribute to the excessive sympathetic activation and hypertension in obesity. Blockage of the AAR attenuates the excessive sympathetic activity and hypertension. Leptin may be one of sensors in the WAT for the AAR, and is involved in the enhanced AAR in obesity and hypertension. This review focuses on the neuroanatomical basis and physiological functions of the AAR, and the important role of the enhanced AAR in the pathogenesis of obesity hypertension.