The relationship between obesity and hypertension is well established both in children and adults. The mechanisms through which obesity directly causes hypertension are still an area of research. Activation of the sympathetic nervous system has been considered to have an important function in the pathogenesis of obesity-related hypertension. The arterial-pressure control mechanism of diuresis and natriuresis, according to the principle of infinite feedback gain, seems to be shifted toward higher blood-pressure levels in obese individuals. During the early phases of obesity, primary sodium retention exists as a result of increase in renal tubular reabsorption. Extracellular-fluid volume is expanded and the kidney-fluid apparatus is resetted to a hypertensive level, consistent with a model of hypertension because of volume overload. Plasma renin activity, angiotensinogen, angiotensin II and aldosterone values display significant increase during obesity. Insulin resistance and inflammation may promote an altered profile of vascular function and consequently hypertension. Leptin and other neuropeptides are possible links between obesity and the development of hypertension. Obesity should be considered as a chronic medical condition, which is likely to require long-term treatment. Understanding of the mechanisms associated with obesity-related hypertension is essential for successful treatment strategies. Hypertension Research (2010) 33, 386-393; doi:10.1038/hr.2010.9Keywords: leptin; obesity; pressure natriuresis; rennin-angiotensin-aldosterone system; sympathetic nervous system INTRODUCTION Obesity is a common disorder that develops from the interaction between the genotype and the environment and involves social, behavioral, cultural, physiological, metabolic and genetic factors. A large number of studies have shown that obesity has an important negative impact on health in a population, leading to the recommendation for general practitioners to have an important function in the management of this condition and of its associated comorbidities such as hypertension, hyperlipidemia and hyperinsulinemia/insulin resistance. The relationship between obesity and hypertension is well established both in adults and children. 1,2 Obese individuals exhibit higher levels of office as well as ambulatory blood pressure (BP) from childhood to old age. Obese subjects display higher BP levels than non-obese individuals even in the normotensive range. The combination of obesity, hypertension and other cardiovascular risk factors significantly increases the probability of adverse cardiovascular outcomes, and raises considerations for aggressive treatment strategies. 3 The mechanisms through which obesity directly causes hypertension are still an area of research. Human and animal studies have elucidated the function of adipose tissue derivatives (adipokines and cytokines), neurohumoral pathways, metabolic functions and modulation of pressor/depressor mechanisms. Although obesity-related hypertension may be the result of a combinatio...

Lorcaserin ((1R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine HCl) is a selective 5-HT 2C receptor agonist with clinical efficacy in phase-III obesity trials. Based on evidence that this drug class also affects behaviors motivated by drug reinforcement, we compared the effect of lorcaserin on behavior maintained by food and nicotine reinforcement, as well as the stimulant and discriminative stimulus properties of nicotine in the rat. Acutely administered lorcaserin (0.3-3 mg/kg, subcutaneous (SC)) dose dependently reduced feeding induced by 22-h food deprivation or palatability. Effects up to 1 mg/kg were consistent with a specific effect on feeding motivation. Lorcaserin (0.6-1 mg/kg, SC) reduced operant responding for food on progressive and fixed ratio schedules of reinforcement. In this dose range lorcaserin also reversed the motor stimulant effect of nicotine, reduced intravenous self-administration of nicotine, and attenuated the nicotine cue in rats trained to discriminate nicotine from saline. Lorcaserin also reduced the reinstatement of nicotine-seeking behavior elicited by a compound cue comprising a nicotine prime and conditioned stimulus previously paired with nicotine reinforcement. Lorcaserin did not reinstate nicotine-seeking behavior or substitute for a nicotine cue. Finally, lorcaserin (0.3-1 mg/kg) reduced nicotine-induced increases in anticipatory responding, a measure of impulsive action, in rats performing the fivechoice serial reaction time task. Importantly, these results indicate that lorcaserin, and likely other selective 5-HT 2C receptor agonists, similarly affect both food-and nicotine-motivated behaviors, and nicotine-induced impulsivity. Collectively, these findings highlight a therapeutic potential for 5-HT 2C agonists such as lorcaserin beyond obesity into addictive behaviors, such as nicotine dependence.

Previously, we showed that the 5-HT 2C receptor agonist Ro60-0175 reduces cocaine self-administration, and the ability of cocaine to reinstate responding after extinction of drug-seeking behavior. The present experiments extended these findings further by determining whether the effects of Ro60-0175 on self-administration were sustained with repeated treatment, and whether Ro60-0175 altered reinstatement induced by the pharmacological stressor yohimbine, or by the context in which self-administration occurred. In Experiment 1, Ro60-0175 (1 mg/kg, s.c.) reduced cocaine (0.25 mg/infusion) self-administration maintained by a progressive ratio schedule. This reduction was sustained over eight daily injections. In Experiment 2, rats self-administered cocaine in daily 2 h sessions for 15 days on a FR1 schedule. Following extinction, yohimbine (1 mg/kg, i.p.) reinstated responding, and this effect was reduced dose dependently by Ro60-0175 (0.3-3 mg/kg, s.c.). In Experiment 3, rats were trained to respond for cocaine on a FR1 schedule in a distinct environmental context (A); responding was then extinguished in a different context (B). Reinstatement tests occurred in either context A or B.Responding was reinstated only when rats were tested in the original self-administration context (A). This reinstatement was reduced dose dependently by Ro60-0175. All effects of Ro60-0175 were blocked by the 5-HT 2C receptor antagonist SB242084. Thus, Ro60-0175, acting via 5-HT 2C receptors, reduces cocaine self-administration and cocaine-seeking triggered by a stressor and by drug-associated cues. The effects of Ro60-0175 do not exhibit tolerance within the 8-day test period. These results indicate that selective 5-HT 2C receptor agonists may be a useful pharmacological strategy for treatment of drug abuse.

The purpose of this study was to investigate differences in left ventricular mass index (LVMI) and the prevalence of left ventricular hypertrophy (LVH) in children and adolescents classified as normotensives, prehypertensives and hypertensives by ambulatory blood pressure (BP) levels. A total of 124 consecutive children and adolescents aged 5 to 18 years were analysed. Patients underwent 24 h ambulatory blood pressure monitoring (ABPM) and echocardiography. Hypertensive and prehypertensive subjects had significantly higher LVMI than normotensives (36.8 +/- 8.4 g/m(2.7) and 34.1 +/- 3.4 g/m(2.7) vs. 29.5 +/- 8.3 g/m(2.7), P < 0.01 and P < 0.05, respectively). In multivariate analysis predictors for LVMI were body mass index (BMI) z score and hypertension (R-squared = 0.31). LVMI values in hypertensive subjects were significantly higher than those of normotensives even after adjustment for age, sex and BMI z score. The prevalence of LVH was significantly higher in the prehypertensive compared to normotensive subjects, and was equal to that of the hypertensive subjects. Hypertension and prehypertension in children and adolescents were associated with pathologically elevated LVMI values. If confirmed in a larger group prehypertensive children may be at risk for target organ damage similar to the condition of established hypertension.

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Results show that the amphetamine-sensitized state impairs prefrontally mediated attentional set shifting. This is consistent with cognitive deficits in schizophrenia and addiction, and with the evidence that amphetamine sensitization is accompanied by functional changes in the mPFC. These results further add to a growing literature showing that activating D(1) receptors in the mPFC improves aspects of cognition.

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