Postoperative hunger after outpatient surgery in patients anesthetized with propofol vs sevoflurane: a randomized-controlled trial

PURPOSE

Previous preclinical and preliminary clinical data suggest an appetite-stimulating effect of propofol compared with halogenated drugs. This study compared the effects of propofol with those of sevoflurane on recovery of hunger during the postoperative period.

METHODS

Patients undergoing outpatient transvaginal oocyte retrieval were randomized to propofol-remifentanil (propofol group) or sevoflurane-remifentanil (sevoflurane group) anesthesia. The primary endpoint was the time before feeling hungry (≥ 50/100 mm on a visual analogue scale). Secondary endpoints included plasma levels of ghrelin, leptin, and insulin (ten minutes, one hour, and two hours after anesthesia), caloric intake at first feed, and discharge readiness time.

RESULTS

In the 58 patients allocated to either the propofol or sevoflurane group, there was no difference in the median [interquartile range] recovery time of hunger (97 [75-138] vs 97 [80-140] min, respectively; median difference, 1; 95% confidence interval [CI], - 15 to 14; P = 0.91); caloric intake (245 [200-343] vs 260 [171-314] kcal; P = 0.39); or discharge readiness time (125 [85-153] vs 125 [95-174] min, P = 0.29). The groups showed no difference in crude plasma levels of ghrelin, leptin, and insulin at any time-point. When peptide plasma levels were expressed as a % change from baseline, there was a higher insulin plasma level one hour after anesthesia in the sevoflurane group (median difference, 4.9%; 95% CI, - 16.2 to 43.4) compared with the propofol group (median difference, - 21.2%; 95% CI, - 35.7 to 9.1; adjusted P = 0.01).

CONCLUSION

Propofol did not accelerate the recovery of hunger compared with sevoflurane after outpatient minor surgery. Moreover, propofol did not have distinguishable effects on other clinical or biological parameters associated with food intake.

TRIAL REGISTRATION

www.ClinicalTrials.gov (NCT02272166); registered 22 October, 2014.

Motivation, risk-taking and sensation seeking behavior in propofol anesthesia exposed peripubertal rats

Adolescent neurodevelopment confer vulnerability to the actions of treatments that produce adaptations in neurocircuitry underlying motivation, impulsivity and reward. Considering wide usage of a sedative-hypnotic agent propofol in clinical practice, we examined whether propofol is a challenging treatment for peripubertal brain. Motivation/hedonic behavior (sucrose preference test), approach/avoidance behavior (elevated plus maze test) and response to dissociative drug phencyclidine (PCP) were studied in peripubertal rats (the rodent model of periadolescence) after propofol anesthesia exposure (PAE). Neurodegeneration (Fluoro-Jade staining) and the expression of proteins (Western blot) involved in excitatory synaptic transmission and activity-dependent synaptic stabilization in the medial prefrontal cortex (mPFC) and striatum (components of motivation/reward circuitry; process both appetitive and aversive events) were examined as well. In peripubertal rats PAE produced 1) transient brain-region specific changes in the expression of N-methyl-d-aspartate (NMDA) receptor subunits NR2A and NR2B, PSD-95 and N-cadherin, without neurotoxicity, 2) hyperlocomotor response to PCP, 3) no changes in preference for palatable 1% sucrose solution and a decrease in food eaten, 4) preference for 20% sucrose solution without changes in food eaten, 5) stretch-attended postures and open arms entries in the elevated plus maze test. Overall, these novel findings show that PAE leaves transient synaptic trace recognized as early form of synaptic plasticity related to passive drug exposure in the brain systems implicated in motivation/reward, increases drug-responsiveness, favors risk-taking and preference of novel/intense stimuli repairing otherwise present motivational deficiency. These findings accentuate multifaceted response to propofol in peripuberty and the importance of environmental stability for the most favorable neurobehavioral recovery.

The hypnotic effect of propofol involves inhibition of GABAergic neurons in the lateral hypothalamus

Propofol is widely used for induction and maintenance of anaesthesia, which causes a rapid loss of consciousness. So far the mechanisms underlying the effect of propofol are still largely unknown. Here, we found that microinjection of propofol in the lateral hypothalamus caused a significant decrease in wakefulness and an increase in the amount of non-rapid eye movement sleep and rapid eye movement sleep. Application of propofol in the lateral hypothalamus affected the electroencephalogram power spectra with a decrease in theta oscillations and an increase in the delta oscillations. Additionally, using whole-cell patch clamp recording, we found propofol inhibited the excitability of the GABAergic neurons in the lateral hypothalamus, which plays a critical role in controlling wakefulness. Altogether, these findings indicate that propofol targets lateral hypothalamus and generates a hypnotic state, which might involve the inhibition of GABAergic neurons. These results provide a novel mechanism to explain propofol-elicited anaesthesia.

Anesthetic drugs modulate feeding behavior and hypothalamic expression of the POMC polypeptide precursor and the NPY neuropeptide

Background

Several hypnotic drugs have been previously identified as modulators of food intake, but exact mechanisms remain unknown. Feeding behavior implicates several neuronal populations in the hypothalamic arcuate nucleus including orexigenic neuropeptide Y and anorexigenic pro-opiomelanocortin producing neurons. The aim of this study was to investigate in mice the impact of different hypnotic drugs on food consumption and neuropeptide Y or pro-opiomelanocortine mRNA expression level in the hypothalamic arcuate nucleus.

Methods

Saline control, isoflurane, thiopental, midazolam or propofol were administered to C57Bl/6 mice. Feeding behavior was evaluated during 6 h. In situ hybridization of neuropeptide Y and pro-opiomelanocortine mRNAs in the hypothalamus brain region was also performed. Data were analyzed by Kruskal Wallis test and analysis of variance (p < 0.05).

Results

Midazolam, thiopental and propofol induced feeding behavior. Midazolam and thiopental increased neuropeptide Y mRNA level (respectively by 106 and 125%, p < 0.001) compared with control. Propofol and midazolam decreased pro-opiomelanocortine mRNA level by 31% (p < 0,01) compared with control. Isoflurane increased pro-opiomelanocortine mRNA level by 40% compared with control.

Conclusion

In our murine model, most hypnotics induced food consumption. The hypnotic-induced regulation of neuropeptide Y and pro-opiomelanocortine hypothalamic peptides is associated with this finding. Our data suggest that administration of some hypnotic drugs may affect hypothalamic peptide precursor and neuropeptide expression and concomittantly modulate food intake. Thus, this questions the choice of anesthetics for better care management of patients undergoing major surgery or at risk of undernutrition.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0557-x) contains supplementary material, which is available to authorized users.

Characterization of cerebrospinal fluid (CSF) and plasma NPY levels in normal volunteers over a 24-h timeframe

Neuropeptide Y (NPY) is abundant in mammals, where it contributes to diverse behavioral and physiological functions, centrally and peripherally, but little information is available in regard to NPY cerebrospinal fluid (CSF)/plasma concentration relationships and dynamics. Since plasma NPY levels are commonly used as proxy "biomarkers" for central NPY activity in stress and mental health research in humans this study aims to better characterize the CSF/plasma NPY relationships. Subjects were eleven healthy male volunteers, admitted to the clinical research center for placement of an indwelling CSF catheter, as well as venous catheter, for 24-h collection of CSF NPY (cNPY) and plasma NPY (pNPY) samples. As observed in prior studies, group mean (SE) cNPY concentrations [792.1 (7.80) pg/mL] were higher than pNPY concentrations [220.0 (3.63) pg/mL]. For the eleven normal volunteers who had sufficient common (hourly) pNPY and cNPY data points, analysis of pNPY/cNPY concentration ratios and lagged cross-correlation analysis was completed. Average pNPY/cNPY concentration ratios ranged from .20 to .40 across study subjects, with a mean of .29. pNPY/cNPY cross correlation analyses, computed at varying time lags, were non-significant. An attempt was made to analyze the circadian rhythmicity of NPY secretion, but circadian components were not detectable. Using 24-h data collection, we characterized CSF/plasma NPY relationships, including presentation of evidence of weak CSF and plasma correlations, an important consideration for study design of NPY in stress or mental health.

Neuropeptide alterations in the tree shrew hypothalamus during volatile anesthesia

Neuropeptides are critical signaling molecules, involved in the regulation of diverse physiological processes including energy metabolism, pain perception and brain cognitive state. Prolonged general anesthesia has an impact on many of these processes, but the regulation of peptides by general anesthetics is poorly understood. In this study, we present an in-depth characterization of the hypothalamic neuropeptides of the tree shrew during volatile isoflurane/nitrous oxide anesthesia administered accompanying a neurosurgical procedure. Using a predicted-peptide database and hybrid spectral analysis, we first identified 85 peptides from the tree shrew hypothalamus. Differential analysis was then performed between control and experimental group animals. The levels of 12 hypothalamic peptides were up-regulated following prolonged general anesthesia. Our study revealed for the first time that several neuropeptides, including alpha-neoendorphin and somatostatin-14, were altered during general anesthesia. Our study broadens the scope for the involvement of neuropeptides in volatile anesthesia regulation, opening the possibility for investigating the associated regulatory mechanisms.

Lower plasma neuropeptide Y level in patients with atypical febrile convulsions

Febrile convulsion (FC) is the most common neurological disease in children. Cases with seizures that persist for more than 15 minutes or recurrent seizures within the same febrile illness are considered to be atypical and may have a different prognosis. Neuropeptide Y (NPY), an endogenous anticonvulsant that is widely distributed throughout the central nervous system, including the hippocampus, is known to prevent seizures by increasing the seizure threshold. Based on our previously finding that patients with atypical FC have lower concentrations of NPY, we hypothesized that the concentration of NPY may play a role in the development of atypical FC. To investigate this hypothesis, we used a radioimmunoassay to measure the plasma NPY concentration of 60 children with FC (typical FC, n = 46; atypical FC, n = 14) and 56 age-matched controls. The atypical FC group had significantly lower concentrations of NPY than children with typical FC and controls (66.47 +/- 19.11 pmol/L vs. 88.68 +/- 28.50 pmol/L and 86.82 +/- 22.66 pmol/L, respectively). Very low NPY levels were found in two patients; one patient (NPY level: 44.75 pmol/L) experienced prolonged seizures lasting for up to 1 hour and the other had recurrent seizures (three seizures) during the same febrile illness (NPY level: 33.53 pmol/L). These results suggest that patients with inadequate NPY inhibitory activity are more susceptible to atypical FC.

Laparophobia: a cognitive perspective on appetite control in anorexia nervosa

Decades of research have demonstrated that anorexia nervosa (AN) may be associated with aberrant cognition, yet, its role in maintaining stringent dieting has received relatively little attention from mainstream researchers of eating disorders. The purpose of the present article is to highlight cognitive ('top-down') factors that are considered responsible for anticipatory anxiety of stoutness and frank fat-phobia (laparophobia). A cognitive model proposed departs from the formulation suggesting that phobia of over-eating is superimposed on avoidant tendencies ('environmental autonomy syndrome'), whereas excessive exercising becomes a natural coping strategy with laparophobia, an instrument of reward. AN ideation involves complex neuronal circuitries and multiple neurochemical components that may conceivably represent a mirror image of those underlying obesity. The emphasis on phobia and aberrant membrane excitability akin to channelopathies behoves the clinicians to be aware of potential uses of drugs acting at the gamma-aminobutyric acid and the N-methyl-D-aspartate/AMPA [2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl) propionic acid] receptors sites as the adjuncts to conventional agents in managing AN.

The sensitivity of hyperpolarization-activated cation current (Ih) to propofol in rat area postrema neurons

Area postrema neurons mediate various autonomic responses, including emesis. We examined the effects of propofol, a widely used anesthetic with antiemetic properties, on the hyperpolarization-activated cation current (Ih) in rat area postrema neurons using a slice patch-clamp technique. Although propofol suppressed Ih of area postrema neurons in a dose-dependent manner that was similar to what we observed for the hippocampal CA1 neurons, the IC50 for Ih in area postrema neurons (38 microM) was more than six times less than that found for hippocampal CA1 neurons (235 microM). We conclude that rat area postrema neurons are exquisitely sensitive to propofol. Given that reductions of Ih are associated with decreased excitability in neurons, we believe that the known antiemetic effects of propofol anesthesia are at least partly a result of a direct action on area postrema neurons to lower their excitability.

Nausea and vomiting after laparoscopic surgery are not associated with an increased peripheral release of serotonin

PURPOSE

To determine whether patients suffering postoperative nausea and vomiting (PONV) present a different serotonin release pattern from those who do not present this complication.

METHODS

Forty-eight consecutive women undergoing outpatient laparoscopic tubal ligation were enrolled in this prospective, cumulative case-control study. The study compared serotonin activity in 15 patients totally free of emetic symptoms (asymptomatic group) and, among patients with PONV (n = 33), those 15 who presented the most severe symptoms (PONV group). Patients were anesthetized with a regimen including sufentanil (0.1-0.3 microg x kg(-1)) plus thiopental (3-5 mg x kg(-1)) for induction and isoflurane (0.6-1%) in nitrous oxide (60%) for maintenance. Peripheral serotonin activity was assessed by measurement with high-performance liquid chromatography of serotonin's principal urinary metabolite: 5-hydroxyindoacetic acid (5-HIAA) corrected for urinary creatinine.

RESULTS

The preoperative and postoperative urinary 5-HIAA:creatinine ratios were 6.9 ng x microg(-1) (confidence interval; CI 95%, 2.7-11.0) and 5.9 ng x microg(-1) (CI 95%, 2.4-9.4) respectively in the asymptomatic group (P = 0.69), and were 5.1 ng x microg(-1) (CI 95%, 2.5-7.7) and 5.6 ng x micro(-1) (CI 95%, 3.4-7.7) respectively in the PONV group (P = 0.75). There was also no difference between groups in the variation of 5-HIAA:creatinine ratios from the preoperative to the postoperative period (P = 0.21).

CONCLUSION

PONV after laparoscopic tubal ligation are not associated with an increased urinary excretion of serotonin metabolites. Patients with severe PONV present a peripheral serotonin release comparable to asymptomatic patients.