Vertebroplasty versus Active Control Intervention for Chronic Osteoporotic Vertebral Compression Fractures: The VERTOS V Randomized Controlled Trial

Background Evidence regarding percutaneous vertebroplasty (PV) for chronic painful osteoporotic vertebral compression fractures (OVCFs) remains limited. Purpose To compare pain relief, quality of life, and disability between PV and active control (anesthetic infiltration) interventions for chronic OVCF. Materials and Methods This prospective randomized clinical trial was conducted between May 2013 and June 2019 in participants with pain due to OVCF lasting longer than 3 months with bone marrow edema present at MRI. Study participants were randomly assigned to undergo PV (n = 40) or active control intervention (n = 40). The primary outcome was pain severity, assessed with the visual analog scale (VAS) (range, 0-10) during 12 months after treatment. Secondary outcomes included Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO) score (range, 0-100) and Roland Morris Disability Questionnaire (RMDQ) score (range, 0-100). Outcomes were analyzed according to a longitudinal multilevel model used to test the difference between groups in change from baseline across follow-up. Results The mean age of the 80 participants (54 women) was 69 years ± 10 (SD) in the PV group and 71 years ± 10 in the active control group. VAS score was 7.6 (95% CI: 7.0, 8.2) in the PV group and 7.3 (95% CI: 6.9, 7.8) in the active control group at baseline (P = .47) and 3.9 (95% CI: 3.1, 4.8) and 5.1 (95% CI: 4.3, 6.0), respectively, at month 12 (P = .045). At month 12, the group difference from baseline was 1.3 (95% CI: 0.1, 2.6; P = .02) for VAS, 5.2 (95% CI: 0.9, 9.4; P = .02) for QUALEFFO, and 7.1 (95% CI: -3.3, 17.5; P = .18) for RMDQ, favoring the PV group. Conclusion In the treatment of pain caused by chronic OVCFs, PV is more effective for pain relief and quality of life improvement than anesthetic injection alone, with similar improvement for disability between the groups. Clinical trial registration no. NCT01963039 © RSNA, 2023 See also the editorial by Beall and De Leacy in this issue.

Predictive Factors for Sustained Pain after (sub)acute Osteoporotic Vertebral Fractures. Combined Results from the VERTOS II and VERTOS IV Trial

Purpose

Osteoporotic vertebral compression fractures are treated conservatively or in selected cases with percutaneous vertebroplasty (PV). The purpose of this retrospective analysis is to determine predictive factors for a high visual analogue scale (VAS) pain score after conservative, sham or PV and is based on previously published randomized trials.

Methods

The VERTOS II compared conservative versus PV, and VERTOS IV compared sham versus PV treatment. The conservative group received pain medication. The sham and PV group received subcutaneous lidocaine/bupivacaine. In addition, the PV group received cementation, which was simulated in the sham group. Nineteen different predictors of high (≥ 5) versus low (< 5) VAS pain score at 12 months were investigated.

Results

20.7% of patients in the PV group demonstrated a VAS ≥ 5 at the 12-month, compared to 40.1% in the conservative or sham group, with a significant difference (χ²(1) = 15.26, p < 0.0001, OR = 2.57, 95% CI = 1.59 to 4.15). In the subgroup analysis, we detected five predictors for the risk of high pain scores (VAS ≥ 5 after 12 months follow-up), namely: female, baseline VAS > 8, long-term baseline pain, mild/severe Genant and new fractures.

Conclusions

Statistically significant more patients had a high pain score at 12 months in the sham and conservative group when compared with the PV group. Five predictors were identified for sustained high local back pain, regardless of the received treatment. Patients with moderate fracture deformity were less likely to have high pain scores at 12 months if they received PV than if they had sham or conservative therapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-022-03170-7.

[Osteomalacia following intravenous iron suppletion]

BACKGROUND

Ferric carboxymaltose (FCM) is highly effective in supplementing iron-deficiency anemia and frequently used. However, it can severely interfere with the phosphate metabolism.

CASE DESCRIPTION

A 63 year old man with iron-deficiency anemia due to hereditary hemorrhagic telangiectasia was treated with intravenous FCM. After initiation of the FCM he developed generalized bone and muscle pain as well as insufficiency fractures. Treatment with colecalciferol was started. However, the bone pain increased and further investigation showed a hypophosphatemicosteomalacia with high urine phosphate loss suggesting renal phosphate wasting. Serum FGF23 level was increased confirming the diagnosis of FGF23 mediated hypophosphatemicosteomalacia induced by intravenous iron suppletion.

CONCLUSION

FCM injections may cause FGF23 mediated hypophosphatemia already 4 weeks after suppletion. Therefore it is recommended that serum phosphate levels should be checked frequently. In patients developing hypophosphatemia, a non-maltose form of iron suppletion must be started as well as active vitamin D.

Sweet dreams or bitter nightmare: a narrative review of 25 years of research on the role of sleep in diabetes and the contributions of behavioural science

The aim of this review was to provide an overview of developments, clinical implications and gaps in knowledge regarding the relationship between diabetes and sleep over the past 25 years, with special focus on contributions from the behavioural sciences. Multiple prospective observational and experimental studies have shown a link between suboptimal sleep and impaired glucose tolerance, decreased insulin sensitivity and the development of type 2 diabetes. While prevalence rates of suboptimal sleep vary widely according to definition, assessment and sample, suboptimal subjective sleep quality appears to be a common reality for one-third of people with type 1 diabetes and over half of people with type 2 diabetes. Both physiological and psychosocial factors may impair sleep in these groups. In turn, suboptimal sleep can negatively affect glycaemic outcomes directly or indirectly via suboptimal daytime functioning (energy, mood, cognition) and self-care behaviours. Technological devices supporting diabetes self-care may have both negative and positive effects. Diabetes and its treatment also affect the sleep of significant others. Research on the merits of interventions aimed at improving sleep for people with diabetes is in its infancy. Diabetes and sleep appear to be reciprocally related. Discussion of sleep deserves a central place in regular diabetes care. Multi-day, multi-method studies may shed more light on the complex relationship between sleep and diabetes at an individual level. Intervention studies are warranted to examine the potential of sleep interventions in improving outcomes for people with diabetes.

Excellent response to pasireotide therapy in an aggressive and dopamine-resistant prolactinoma

Prolactinomas are the most commonly encountered pituitary adenomas in the clinical setting. While most can be controlled by dopamine agonists, a subset of prolactinomas are dopamine-resistant and very aggressive. In such tumors, the treatment of choice is neurosurgery and radiotherapy, with or without temozolomide. Here, we report a patient with an highly aggressive, dopamine-resistant prolactinoma, who only achieved biochemical and tumor control during pasireotide long-acting release (PAS-LAR) therapy, a second-generation somatostatin receptor ligand (SRL). Interestingly, cystic degeneration, tumor cell necrosis or both was observed after PAS-LAR administration suggesting an antitumor effect. This case shows that PAS-LAR therapy holds clinical potential in selective aggressive, dopamine-resistant prolactinomas that express somatostatin (SST) receptor subtype 5 and appears to be a potential new treatment option before starting temozolomide. In addition, PAS-LAR therapy may induce cystic degeneration, tumor cell necrosis or both in prolactinomas.

Vertebroplasty versus sham procedure for painful acute osteoporotic vertebral compression fractures (VERTOS IV): randomised sham controlled clinical trial

OBJECTIVE

To assess whether percutaneous vertebroplasty results in more pain relief than a sham procedure in patients with acute osteoporotic compression fractures of the vertebral body.

DESIGN

Randomised, double blind, sham controlled clinical trial.

SETTING

Four community hospitals in the Netherlands, 2011-15.

PARTICIPANTS

180 participants requiring treatment for acute osteoporotic vertebral compression fractures were randomised to either vertebroplasty (n=91) or a sham procedure (n=89).

INTERVENTIONS

Participants received local subcutaneous lidocaine (lignocaine) and bupivacaine at each pedicle. The vertebroplasty group also received cementation, which was simulated in the sham procedure group.

MAIN OUTCOME MEASURES

Main outcome measure was mean reduction in visual analogue scale (VAS) scores at one day, one week, and one, three, six, and 12 months. Clinically significant pain relief was defined as a decrease of 1.5 points in VAS scores from baseline. Secondary outcome measures were the differences between groups for changes in the quality of life for osteoporosis and Roland-Morris disability questionnaire scores during 12 months' follow-up.

RESULTS

The mean reduction in VAS score was statistically significant in the vertebroplasty and sham procedure groups at all follow-up points after the procedure compared with baseline. The mean difference in VAS scores between groups was 0.20 (95% confidence interval -0.53 to 0.94) at baseline, -0.43 (-1.17 to 0.31) at one day, -0.11 (-0.85 to 0.63) at one week, 0.41 (-0.33 to 1.15) at one month, 0.21 (-0.54 to 0.96) at three months, 0.39 (-0.37 to 1.15) at six months, and 0.45 (-0.37 to 1.24) at 12 months. These changes in VAS scores did not, however, differ statistically significantly between the groups during 12 months' follow-up. The results for secondary outcomes were not statistically significant. Use of analgesics (non-opioids, weak opioids, strong opioids) decreased statistically significantly in both groups at all time points, with no statistically significant differences between groups. Two adverse events occurred in the vertebroplasty group: one respiratory insufficiency and one vasovagal reaction.

CONCLUSIONS

Percutaneous vertebroplasty did not result in statistically significantly greater pain relief than a sham procedure during 12 months' follow-up among patients with acute osteoporotic vertebral compression fractures.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01200277.

Subjective sleep impairment in adults with type 1 or type 2 diabetes: Results from Diabetes MILES--The Netherlands

AIMS

Despite growing recognition of the impact of sleep on diabetes, a clear profile of people with diabetes regarding subjective sleep impairment has yet to be established. This study examines: (1) subjective sleep characteristics in adults with type 1 and type 2 diabetes; (2) the relationship of poor subjective sleep quality with glycaemic control, self-care and daytime functioning; (3) possible risk markers for poor sleep quality.

METHODS

In a cross-sectional study, Dutch adults with type 1 (n=267) or type 2 diabetes (n=361) completed an online survey, including the Pittsburgh Sleep Quality Index (PSQI), socio-demographic, clinical, self-care and psychological measures.

RESULTS

Poor sleep quality (PSQI-score >5) was reported by 31% of adults with type 1 and 42% of adults with type 2 diabetes. Participants with good and poor sleep quality did not differ in self-reported HbA1c or the frequency of meeting lifestyle recommendations. Poor sleep quality was related to a higher self-care burden and higher levels of daytime sleepiness, fatigue, depressive and anxiety symptoms, and diabetes-specific distress. In multivariable logistic regression analyses examining risk markers, poor sleep quality was associated with depressive symptoms in adults with type 1 (OR=1.39, 95% CI 1.25-1.54) and type 2 diabetes (OR=1.31, 1.16-1.47), and with being female in those with type 2 diabetes (OR=2.72, 1.42-5.20).

CONCLUSIONS

Poor subjective sleep quality is prevalent both in adults with type 1 and type 2 diabetes, and is related to poor daytime functioning and higher self-care burden. The temporal relation with depression and merits of therapy should be explored.

Insulin resistance in patients with type 1 diabetes assessed by glucose clamp studies: systematic review and meta-analysis

OBJECTIVE

The aim of this study was to perform a systematic review and meta-analysis on insulin resistance in adult patients with type 1 diabetes mellitus compared to healthy controls, assessed by hyperinsulinemic euglycemic clamp studies.

DESIGN AND METHODS

We conducted a systematic search of publications using PubMed, EMBASE, Web of Science and COCHRANE Library. Hyperinsulinemic euglycemic clamp studies comparing adult patients with type 1 diabetes mellitus to healthy controls were eligible. Primary outcome measures were pooled mean differences of insulin sensitivity of endogenous glucose production (EGP), of glucose uptake and of lipolysis. We estimated mean (standardized) differences and 95% CIs using random effects meta-analysis.

RESULTS

We included 38 publications in this meta-analysis. The weighed mean differences in EGP during hyperinsulinemia between patients and controls was 0.88 (95% CI: 0.47, 1.29) in the basal state and 0.52 (95% CI: 0.09, 0.95) in insulin stimulated conditions, indicating decreased hepatic insulin sensitivity in patients. Insulin sensitivity of glucose uptake was either reported as M value (M), glucose infusion rate (GIR), glucose disposal rate (GDR) or metabolic clearance rate (MCR). Weighed mean differences were similar for M -3.98 (95% CI: -4.68, -3.29) and GIR -4.61 (95% CI: -5.86, -3.53). Weighed mean difference for GDR was -2.43 (95% CI: -3.03, -1.83) and -3.29 (95% CI: -5.37, -1.22) for MCR, indicating decreased peripheral insulin sensitivity in patients. Insulin mediated inhibition of lipolysis was decreased in patients, reflected by increased non-esterified fatty acid levels.

CONCLUSIONS

Insulin resistance is a prominent feature of patients with type 1 diabetes mellitus and involves hepatic, peripheral and adipose tissues.

Impaired sustained attention in adult patients with type 1 diabetes is related to diabetes per se

BACKGROUND

Patients with type 1 diabetes have altered sleep characteristics and are thought to have deficits in sustained attention. We compared the sustained attention to response task (SART) of patients with type 1 diabetes to that of healthy controls, and related results with sleep characteristics and disease-related factors.

METHODS

SART was applied in 122 patients and 109 controls. Glucoregulation was assessed by HbA1c values and a questionnaire assessing glycaemic history. Clinical parameters were obtained from medical charts. Polyneuropathy was assessed by neurological examination and quantitative sensory testing. Sleep characteristics were assessed with sleep questionnaires. Anxiety and depression scores were assessed by the Hospital Anxiety and Depression Scale.

RESULTS

The SART reaction time (RT) was significantly longer than in controls (327 ± 5 vs. 285 ± 3 ms, p < 0.001), although there were no significant differences in error scores. Repeated measurement analyses showed that diabetes per se was associated with prolonged RT (p < 0.001) and more commission errors (p = 0.010). None of the sleep-related and diabetes-related factors were significantly associated with these SART parameters.

CONCLUSIONS

Patients with type 1 diabetes had impaired sustained attention, which was associated with diabetes per se but not with disturbed sleep characteristics.

Sleep characteristics and insulin sensitivity in humans

The diurnal variation of the geophysical position of the earth in relation to the sun has imposed considerable evolutionary pressure. The suprachiasmatic nucleus, which serves as the central biological clock, receives the input regarding light-dark through the optic nerves. This nucleus in turn conveys output in a diurnal fashion to other hypothalamic nuclei and to the autonomic nervous system. Sleep is the most extreme phenotypical adaptation to this diurnal light-dark cycle. In recent years, sleep duration has been reduced and sleep deprivation has become endemic in our modern 24/7 society, either by voluntary sleep restriction and/or through sleep disorders. Experimental studies in humans have documented that sleep deprivation induces insulin resistance in multiple metabolic pathways in both healthy subjects and patients with type 1 diabetes. Epidemiological studies have documented that sleep duration is an important risk factor for development of insulin resistance and type 2 diabetes. Several potential pathways have been suggested to contribute to insulin resistance after sleep restriction, including altered function of the autonomic nervous system, endocrine changes, and an altered inflammatory state. Nonetheless, the causal factors explaining the relation between altered sleep characteristics and insulin resistance in multiple organs need additional study, and most likely include central autonomic pathways.

Insulin resistance in multiple tissues in patients with type 1 diabetes mellitus on long-term continuous subcutaneous insulin infusion therapy

BACKGROUND

The aim of this study was to determine whether insulin resistance is present in lean patients with uncomplicated type 1 diabetes mellitus on long-term continuous subcutaneous insulin infusion (CSII), compared with matched healthy controls.

METHODS

We studied eight patients (four men and four women) with type 1 diabetes mellitus on continuous subcutaneous insulin infusion and eight healthy controls, matched for age, gender and body mass index. Insulin sensitivity was measured by hyperinsulinemic euglycemic clamp studies with infusion of [6,6-(2) H(2)] glucose.

RESULTS

Endogenous glucose production did not differ in the basal state between patients and controls. However, endogenous glucose production was less suppressed during clamp conditions in patients compared with controls (64% vs 79%, p = 0.01), indicating decreased hepatic insulin sensitivity. During the clamp study, glucose disposal rate was ~38% lower in patients compared with controls (24.4 ± 2.5 vs 39.7 ± 5.6 µmol/kgLBM/min, p = 0.04). Accordingly, the rate of infusion of glucose was ~51% lower in patients (17.7 ± 2.8 vs 39.7 ± 5.7 µmol/kgLBM/min, p = 0.02). Finally, non-esterified fatty acids levels were ~2.5 times higher in patients during steady state clamp conditions (150 ± 26 vs 58 ± 4 pmol/L, p = 0.01), reflecting decreased insulin sensitivity of lipolysis.

CONCLUSIONS

Insulin resistance is a prominent feature of lean patients with type 1 diabetes mellitus, despite long term and stable treatment with continuous subcutaneous insulin infusion. Insulin resistance in type 1 diabetes involves both lipolysis, hepatic and peripheral glucose metabolism.

Disturbed subjective sleep characteristics in adult patients with long-standing type 1 diabetes mellitus

AIMS/HYPOTHESIS

Decreased sleep duration and/or impaired sleep quality negatively influence glucoregulation. The aim of this study was to assess subjective sleep characteristics in patients with type 1 diabetes, to relate sleep characteristics to long-term glycaemic control and to assess possible risk factors for impaired sleep.

METHODS

We studied 99 adult patients with type 1 diabetes (55 men, 44 women, duration of diabetes 26.9 ± 1.2 years) and 99 age-, sex- and BMI-matched non-diabetic controls. Subjective sleep characteristics were assessed by validated questionnaires, i.e. Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and the Berlin Questionnaire. Glucoregulation was assessed by HbA(1c) values. Clinical variables were obtained from medical charts. Depression was assessed by the Hospital Anxiety and Depression Scale (HADS). Peripheral polyneuropathy was assessed by neurological examination and quantitative sensory testing.

RESULTS

Of the patients with type 1 diabetes, 35% had subjective poor sleep quality compared with 20% of the control participants (p = 0.021). A higher proportion of the patients with type 1 diabetes were at increased risk for obstructive sleep apnoea (OSA) (17.2% vs 5.1%, p = 0.012). There was no significant association between individual sleep characteristics and HbA(1c) values. On logistic regression analysis, the HADS depression score, presence of peripheral polyneuropathy, habitual snoring and other sleep disturbances (e.g. hypoglycaemia) were independently associated with poor sleep quality.

CONCLUSIONS/INTERPRETATION

Adult patients with long-standing type 1 diabetes mellitus have disturbed subjective sleep quality and a higher risk for OSA compared with control participants. Subjective sleep disturbances are part of the complex syndrome of long-standing type 1 diabetes.

Patients previously treated for nonfunctioning pituitary macroadenomas have disturbed sleep characteristics, circadian movement rhythm, and subjective sleep quality

CONTEXT AND OBJECTIVE

Fatigue and excessive sleepiness have been reported after treatment of nonfunctioning pituitary macroadenomas (NFMA). Because these complaints may be caused by disturbed nocturnal sleep, we evaluated objective sleep characteristics in patients treated for NFMA.

DESIGN

We conducted a controlled cross-sectional study.

SUBJECTS AND METHODS

We studied 17 patients (8 women; mean age, 54 yr) in remission of NFMA during long-term follow-up (8 yr; range, 1-18 yr) after surgery (n = 17) and additional radiotherapy (n = 5) without comorbidity except for hypopituitarism and 17 controls matched for age, gender, and body mass index. Sleep was assessed by nocturnal polysomnography, sleep and diurnal movement patterns by actigraphy, and quality of life and subjective sleep characteristics by questionnaires.

RESULTS

Compared to controls, patients had reduced sleep efficiency, less rapid eye movement sleep, more N1 sleep, and more awakenings in the absence of excessive apnea or periodic limb movements. Actigraphy revealed a longer sleep duration and profound disturbances in diurnal movement patterns, with more awakenings at night and less activity during the day. Patients scored higher on fatigue and reported impaired quality of life.

CONCLUSION

Patients previously treated for NFMA suffer from decreased subjective sleep quality, disturbed distribution of sleep stages, and disturbed circadian movement rhythm. These observations indicate that altered sleep characteristics may be a factor contributing to impaired quality of life and increased fatigue in patients treated for NFMA.

Partial sleep restriction decreases insulin sensitivity in type 1 diabetes

OBJECTIVE

Sleep restriction results in decreased insulin sensitivity and glucose tolerance in healthy subjects. We hypothesized that sleep duration is also a determinant of insulin sensitivity in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

We studied seven patients (three men, four women) with type 1 diabetes: mean age 44 +/- 7 years, BMI 23.5 +/- 0.9 kg/m(2), and A1C 7.6 +/- 0.3%. They were studied once after a night of normal sleep duration and once after a night of only 4 h of sleep. Sleep characteristics were assessed by polysomnography. Insulin sensitivity was measured by hyperinsulinemic euglycemic clamp studies with an infusion of [6,6-(2)H(2)]glucose. RESULTS Sleep duration was shorter in the night with sleep restriction than in the unrestricted night (469 +/- 8.5 vs. 222 +/- 7.1 min, P = 0.02). Sleep restriction did not affect basal levels of glucose, nonesterified fatty acids (NEFAs), or endogenous glucose production. Endogenous glucose production during the hyperinsulinemic clamp was not altered during the night of sleep restriction compared with the night of unrestricted sleep (6.2 +/- 0.8 vs. 6.9 +/- 0.6 micromol x kg lean body mass(-1) x min(-1), NS). In contrast, sleep restriction decreased the glucose disposal rate during the clamp (25.5 +/- 2.6 vs. 22.0 +/- 2.1 micromol x kg lean body mass(-1) x min(-1), P = 0.04), reflecting decreased peripheral insulin sensitivity. Accordingly, sleep restriction decreased the rate of glucose infusion by approximately 21% (P = 0.04). Sleep restriction did not alter plasma NEFA levels during the clamp (143 +/- 29 vs. 133 +/- 29 micromol/l, NS).

CONCLUSIONS

Partial sleep deprivation during a single night induces peripheral insulin resistance in these seven patients with type 1 diabetes. Therefore, sleep duration is a determinant of insulin sensitivity in patients with type 1 diabetes.

A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects

BACKGROUND

Subsequent nights with partial sleep restriction result in impaired glucose tolerance, but the effects on insulin sensitivity have not been characterized.

OBJECTIVE

The aim of this study was to evaluate the effect of a single night of partial sleep restriction on parameters of insulin sensitivity.

RESEARCH DESIGN AND METHODS

Nine healthy subjects (five men, four women) were studied once after a night of normal sleep duration (sleep allowed from 2300 to 0730 h), and once after a night of 4 h of sleep (sleep allowed from 0100 to 0500 h). Sleep characteristics were assessed by polysomnography. Insulin sensitivity was measured by hyperinsulinemic euglycemic clamp studies (from 1130 to 1430 h) with infusion of [6,6-(2)H(2)]glucose.

RESULTS

Sleep duration was shorter in the night with sleep restriction than in the unrestricted night (226 +/- 11 vs. 454 +/- 9 min; P< 0.0001). Sleep restriction did not affect basal levels of glucose, nonesterified fatty acids, insulin, or endogenous glucose production. Sleep restriction resulted in increased endogenous glucose production during the hyperinsulinemic clamp study compared to the unrestricted night (4.4 +/- 0.3 vs. 3.6 +/- 0.2 micromol x kg lean body mass(-1) x min(-1); P = 0.017), indicating hepatic insulin resistance. In addition, sleep restriction decreased the glucose disposal rate during the clamp (32.5 +/- 3.6 vs. 40.7 +/- 5.1 micromol x kg lean body mass(-1) x min(-1); P = 0009), reflecting decreased peripheral insulin sensitivity. Accordingly, sleep restriction decreased the rate of glucose infusion by approximately 25% (P = 0.001). Sleep restriction increased plasma nonesterified fatty acid levels during the clamp study (68 +/- 5 vs. 57 +/- 4 micromol/liter; P = 0.005).

CONCLUSIONS

Partial sleep deprivation during only a single night induces insulin resistance in multiple metabolic pathways in healthy subjects. This physiological observation may be of relevance for variations in glucoregulation in patients with type 1 and type 2 diabetes.

High fat diet induced hepatic insulin resistance is not related to changes in hypothalamic mRNA expression of NPY, AgRP, POMC and CART in mice

The hypothalamic circuitry, apart from its impact on food intake, modulates insulin sensitivity to adapt metabolic conditions in the face of environmental fluctuations in nutrient availability. The purpose of the present study was to investigate the effects of 2 weeks high fat feeding in wildtype mice on (1) insulin sensitivity and triglyceride accumulation in liver and muscle in relation to (2) mRNA expression levels of Neuropeptide Y (NPY), Agouti-related protein (AgRP), pro-opiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus. Two weeks of high fat feeding induced hepatic insulin resistance in the presence of increased hepatic triglyceride accumulation. In muscle, however, 2 weeks of high fat feeding did not result in changes in insulin sensitivity or in triglyceride content. mRNA expression levels of NPY, AgRP, POMC, and CART in the hypothalamus were not different between the groups. This study shows that 2 weeks of high fat feeding in mice does not affect mRNA expression levels of NPY, AgRP, POMC or CART, in the whole hypothalamus, despite induction of hepatic, but not peripheral, insulin resistance. Therefore, a major physiological role of these neuroendocrine factors in the induction of hepatic insulin resistance during a high fat diet seems less likely.

Sixteen hours of fasting differentially affects hepatic and muscle insulin sensitivity in mice

Fasting readily induces hepatic steatosis. Hepatic steatosis is associated with hepatic insulin resistance. The purpose of the present study was to document the effects of 16 h of fasting in wild-type mice on insulin sensitivity in liver and skeletal muscle in relation to 1) tissue accumulation of triglycerides (TGs) and 2) changes in mRNA expression of metabolically relevant genes. Sixteen hours of fasting did not show an effect on hepatic insulin sensitivity in terms of glucose production in the presence of increased hepatic TG content. In muscle, however, fasting resulted in increased insulin sensitivity, with increased muscle glucose uptake without changes in muscle TG content. In liver, fasting resulted in increased mRNA expression of genes promoting gluconeogenesis and TG synthesis but in decreased mRNA expression of genes involved in glycogenolysis and fatty acid synthesis. In muscle, increased mRNA expression of genes promoting glucose uptake, as well as lipogenesis and beta-oxidation, was found. In conclusion, 16 h of fasting does not induce hepatic insulin resistance, although it causes liver steatosis, whereas muscle insulin sensitivity increases without changes in muscle TG content. Therefore, fasting induces differential changes in tissue-specific insulin sensitivity, and liver and muscle TG contents are unlikely to be involved in these changes.