Insulin like growth factor-I in acute subarachnoid hemorrhage: a prospective cohort study

The neurobiology of insulin-like growth factor I: From neuroprotection to modulation of brain states

After decades of research in the neurobiology of IGF-I, its role as a prototypical neurotrophic factor is undisputed. However, many of its actions in the adult brain indicate that this growth factor is not only involved in brain development or in the response to injury. Following a three-layer assessment of its role in the central nervous system, we consider that at the cellular level, IGF-I is indeed a bona fide neurotrophic factor, modulating along ontogeny the generation and function of all the major types of brain cells, contributing to sculpt brain architecture and adaptive responses to damage. At the circuit level, IGF-I modulates neuronal excitability and synaptic plasticity at multiple sites, whereas at the system level, IGF-I intervenes in energy allocation, proteostasis, circadian cycles, mood, and cognition. Local and peripheral sources of brain IGF-I input contribute to a spatially restricted, compartmentalized, and timed modulation of brain activity. To better define these variety of actions, we consider IGF-I a modulator of brain states. This definition aims to reconcile all aspects of IGF-I neurobiology, and may provide a new conceptual framework in the design of future research on the actions of this multitasking neuromodulator in the brain.

Copeptin and insulin-like growth factor-1 predict long-term outcomes after aneurysmal subarachnoid hemorrhage: A large prospective cohort study

OBJECTIVE

The predictive roles of copeptin and insulin-like growth factor-1 (IGF-1) in aneurysmal subarachnoid hemorrhage (aSAH) remain controversial. We aimed to define the relationship between copeptin and IGF-1 levels and functional outcome as well as quality of life (QoL) after aSAH.

METHODS

Patients with aSAH were prospectively enrolled in a tertiary university hospital. Controls were sex- and age-matched healthy subjects. Plasma concentrations of copeptin and IGF-1 were measured on admission. Demographics and clinical, radiological and laboratory characteristics of the patients were collected. Favorable functional outcome was defined as modified Rankins≤2, and QoL was evaluated by the 36-Item Short Form Health Survey (SF-36) 1 year after aSAH. Uni- and multivariable analyses were performed.

RESULTS

One hundred eighteen patients were eligible, with 122 healthy controls were included in this study. Plasma copeptin levels were significantly higher and plasma IGF-1 was lower in patients than in controls. Both copeptin (adjusted HR 4.143 [1.120-15.328], p = 0.033) and IGF-1 levels (adjusted HR 0.089 [0.013-0.602], p = 0.013) were positively associated with 1-year mortality, while only single copeptin and IGF-1 concentrations were independent predictors of poor functional outcome and QoL, respectively.

CONCLUSIONS

Plasma copeptin and IGF-1 levels are abnormal in patients with acute aSAH, and this may reliably predict long-term mortality, functional outcome and QoL.

Plasma Estrogen Levels Are Associated With Severity of Injury and Outcomes After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Biochemical mediators alter cerebral perfusion and have been implicated in delayed cerebral ischemia (DCI) and poor outcomes after aneurysmal subarachnoid hemorrhage (aSAH). Estrogens (estrone [E1] and estradiol [E2]) are mediators with neuroprotective properties that could play a role in DCI. This study explored associations between plasma estrogen levels and outcomes following aSAH.

METHODS

Plasma samples from 1-4, 4-6, and 7-10 days after hemorrhage from 99 adult aSAH patients were analyzed for estrogen levels using liquid chromatography tandem mass spectrometry. DCI was operationalized as radiographic/ultrasonic evidence of impaired cerebral blood flow accompanied by neurological deterioration. Outcomes were assessed using the Modified Rankin Scale at 3 and 12 months after hemorrhage. Statistical analysis included correlation, regression, and group-based trajectory.

RESULTS

Higher E1 and E2 levels were associated with higher Hunt and Hess grade (E1, p = .01; E2, p = .03), the presence of DCI (E1, p = .02; E2, p = .02), and poor 3-month outcomes (E1, p = .002; E2, p = .002). Trajectory analysis identified distinct populations over time for E1 (61% E1 high) and E2 (68% E2 high). Patients in higher trajectory groups had higher Fisher grades (E1, p = .008; E2, p = .01), more frequent DCI (E1, p = .04; E2, p = .08), and worse 3-month outcomes (E1, p = .01; E2, p = .004) than low groups.

CONCLUSIONS

These results provide the first clinical evidence that plasma E1 and E2 concentrations are associated with severity of injury and outcomes after aSAH.

Endothelin-1-induced focal cerebral ischemia in the growth hormone/IGF-1 deficient Lewis Dwarf rat

Aging is a major risk factor for cerebrovascular disease. Growth hormone (GH) and its anabolic mediator, insulin-like growth factor (IGF)-1, decrease with advancing age and this decline has been shown to promote vascular dysfunction. In addition, lower GH/IGF-1 levels are associated with higher stroke mortality in humans. These results suggest that decreased GH/IGF-1 level is an important factor in increased risk of cerebrovascular diseases. This study was designed to assess whether GH/IGF-1-deficiency influences the outcome of cerebral ischemia. We found that endothelin-1-induced middle cerebral artery occlusion resulted in a modest but nonsignificant decrease in cerebral infarct size in GH/IGF-1 deficient dw/dw rats compared with control heterozygous littermates and dw/dw rats with early-life GH treatment. Expression of endothelin receptors and endothelin-1-induced constriction of the middle cerebral arteries were similar in the three experimental groups. Interestingly, dw/dw rats exhibited reduced brain edema and less astrocytic infiltration compared with their heterozygous littermates and this effect was reversed by GH-treatment. Because reactive astrocytes are critical for the regulation of poststroke inflammatory processes, maintenance of the blood-brain barrier and neural repair, further studies are warranted to determine the long-term functional consequences of decreased astrocytic activation in GH/IGF-1 deficient animals after cerebral ischemia.

Muscle atrophy, voluntary activation disturbances, and low serum concentrations of IGF-1 and IGFBP-3 are associated with weakness in people with chronic stroke

BACKGROUND

The muscle weakness that is exhibited poststroke is due to a multifactorial etiology involving the central nervous system and skeletal muscle changes. Insulinlike growth factor 1 (IGF-1) and IGF binding protein 3 (IGFBP-3) have been described as biomarkers of neuromuscular performance in many conditions. However, no information about these biomarkers is available for people with chronic hemiparesis.

OBJECTIVE

The purpose of this study was to investigate possible factors involved in muscle weakness, such as IGF-1 and IGFBP-3 serum concentrations, muscle volume, and neuromuscular performance of the knee flexors and extensors, in people with chronic hemiparesis poststroke.

DESIGN

This was a cross-sectional study.

METHODS

A cross-sectional study was performed on 14 individuals poststroke who were paired with healthy controls. Mobility, function, balance, and quality of life were recorded as outcome measures. Knee flexor and extensor muscle volumes and neuromuscular performance were measured using nuclear magnetic resonance imaging, dynamometry, and electromyography. The serum concentrations of IGF-1 and IGFBP-3 were quantified by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The hemiparetic group had low serum concentrations of IGF-1 (25%) and IGFBP-3 (40%); reduced muscle volume in the vastus medialis (32%), vastus intermedius (29%), biceps femoris (16%), and semitendinosus and semimembranosus (12%) muscles; reduced peak torque, power, and work of the knee flexors and extensors; and altered agonist and antagonist muscle activation compared with controls.

CONCLUSIONS

Low serum concentrations of IGF-1 and IGFBP-3, deficits in neuromuscular performance, selective muscle atrophy, and decreased agonist muscle activation were found in the group with chronic hemiparesis poststroke. Both hemorrhagic and ischemic stroke were considered, and the data reflect a chronic poststroke population with good function.

The relationship between serum insulin-like growth factor I levels and ischemic stroke risk

Objective

The aim of the study was to assess the relationship between insulin-like growth factor I (IGF-I) serum levels and acute ischemic stroke (AIS) in a Chinese population.

Methods

All consecutive patients with first-ever AIS from August 1, 2011 to July 31, 2013 were recruited to participate in the study. The control group comprised 200 subjects matched for age, gender, and conventional vascular risk factors. IGF-I serum levels were determined by chemiluminescence immunoassay. The National Institutes of Health Stroke Scale (NIHSS) score was assessed on admission blinded to serum IGF-I levels.

Results

The median serum IGF-1 levels were significantly (P = 0.011) lower in AIS patients (129; IQR, 109–153 ng/mL) compared with control cases (140; IQR, 125–159 ng/mL). We found that an increased risk of AIS was associated with IGF-I levels ≤135 ng/mL (unadjusted OR: 4.17; 95% CI: 2.52–6.89; P = 0.000). This relationship was confirmed in the dose-response model. In multivariate analysis, there was still an increased risk of AIS associated with IGF-I levels ≤135 ng/mL (OR: 2.16; 95% CI:1.33–3.52; P = 0.002) after adjusting for possible confounders.

Conclusion

Lower IGF-I levels are significantly related to risk of stroke, independent from other traditional and emerging risk factors, suggesting that they may play a role in the pathogenesis of AIS. Thus, strokes were more likely to occur in patients with low serum IGF-I levels in the Chinese population; further, post-ischemic IGF-I therapy may be beneficial for stroke.

Somatotropic and thyroid hormones in the acute phase of subarachnoid haemorrhage

BACKGROUND

Somatotropic and thyroid hormones are probably important for the recovery after acute brain injury. Still, the dynamics of these hormones after spontaneous subarachnoid haemorrhage (SAH) is not well described. The purpose of this study was to investigate the relation between somatotropic and thyroid hormones and clinical factors after SAH.

METHODS

Twenty patients with spontaneous SAH were included prospectively. Serum concentrations of TSH, fT4, T3, IGF-1 and GH were measured once a day for 7 days after SAH. Hormone patterns and serum concentrations were compared to the severity of SAH, neurological condition at admission, clinical course and outcome of the patients.

RESULTS

During the first week after SAH, all patients showed increased GH and IGF-1 concentrations. In the whole group, concentrations of TSH increased, whereas T3 and fT4 decreased. There were no relations of serum concentrations of IGF-1 or GH to clinical condition at admission, clinical course or outcome of the patients. Half of the patients showed low T3 serum concentrations. A complicated course was associated with a deeper fall in TSH and T3 concentrations. There were negative correlations for mean concentrations of TSH and T3 versus WFNS grade and a positive correlation for T3 versus GOS after 6 months, indicating that low concentrations of TSH and T3 were connected to worse SAH grade and poor outcome.

CONCLUSIONS

All patients showed increased GH and IGF-1 concentrations irrespective of the grade of SAH or clinical course. Patients with a complicated clinical course showed a more pronounced fall in TSH and T3 concentrations and low serum T3 concentrations were related to a more serious SAH and poor patient outcome. These results need to be studied further and they may contribute to the accumulated knowledge needed to understand the complex mechanisms influencing the unpredictable clinical course after SAH.

Aneurysmal subarachnoid hemorrhage (aSAH) results in low prevalence of neuro-endocrine dysfunction and NOT deficiency

Neuro-endocrine deficiencies have been argued to be common sequelae after aneurysmal subarachnoid hemorrhage (aSAH). As this, however, does not resemble our clinical experience, we studied the incidence of neuro-endocrine and neuropsychological deficits after aSAH. Twenty-six patients (20 females) were prospectively screened for neuro-endocrine and neuropsychological deficits 3, 6 and 12 months after aSAH. GH, IGF-1, prolactin, LH, FSH, estradiol, testosterone, ACTH as well as cortisol during ACTH-stimulation were assessed. Neuropsychological analysis covered verbal comprehension, short term and working memory, visuospatial construction, figural memory, psychomotor speed, attention, and concentration. During the study period 5 individuals demonstrated neuro-endocrine dysfunction. Hypogonadotrophic hypogonadism resolved spontaneously in 2 patients and central hypothyroidism in one of these patients during the study. After 12 months three patients presented low IGF-1 levels. 73.9% of our cohort was affected by neuropsychological deficits during follow-up. At 3, 6 and 12 months the prevalences were 56.5, 52.6 and 42.1%, respectively. Interestingly, all patients with neuro-endocrine dysfunction presented impaired clinical outcome with a GOS 4 at some time point of the study (GOS 4 vs. 5, 45.5% vs. 0, P = 0.007). We found a low prevalence of neuro-endocrine and a high prevalence of neuropsychological deficits in patients 3, 6 and 12 months after aSAH without significant interrelation. Spontaneous recovery of neuro-endocrine alterations most likely presents an adaption to or dysfunction after severe illness. This hypothesis is strengthened by the fact that only patients with inferior clinical outcome after aSAH as assessed by GOS demonstrated neuro-endocrine dysfunction.

Year in review 2010: Critical Care--Neurocritical care

In 2010 Critical Care published a large number of articles on critical care aspects of neurologic and neurosurgical conditions. These aspects included investigation of diagnostic criteria for bacterial meningitis, critical illness myopathy and their relationship to systemic inflammation. A number of studies investigated the biology of sepsis-related delirium, its biomarkers, its relationship to inflammation and its impact on outcome. Other teams reported on the use of magnetic resonance imaging, biomarkers and electroencephalogram to predict outcome in patients who were comatose following cardiac arrest. Our understanding of the pathophysiology as well as management of subarachnoid hemorrhage was addressed in several papers. Topics included the effect of hemodynamic treatment of delayed cerebral ischemia, pulmonary edema and the impact of subarachnoid hemorrhage on endocrine function. Finally, outcome from neurocritical care and patients' retrospective willingness to consent to the treatment they received were reported.