Links between growth hormone deficiency, adaptation and social phobia

Pediatric obesity-Long-term consequences and effect of weight loss

Childhood obesity is, according to the WHO, one of the most serious challenges of the 21st century. More than 100 million children have obesity today. Already during childhood, almost all organs are at risk of being affected by obesity. In this review, we present the current knowledge about diseases associated with childhood obesity and how they are affected by weight loss. One major causative factor is obesity-induced low-grade chronic inflammation, which can be observed already in preschool children. This inflammation-together with endocrine, paracrine, and metabolic effects of obesity-increases the long-term risk for several severe diseases. Type 2 diabetes is increasingly prevalent in adolescents and young adults who have had obesity during childhood. When it is diagnosed in young individuals, the morbidity and mortality rate is higher than when it occurs later in life, and more dangerous than type 1 diabetes. Childhood obesity also increases the risk for several autoimmune diseases such as multiple sclerosis, Crohn's disease, arthritis, and type 1 diabetes and it is well established that childhood obesity also increases the risk for cardiovascular disease. Consequently, childhood obesity increases the risk for premature mortality, and the mortality rate is three times higher already before 30 years of age compared with the normal population. The risks associated with childhood obesity are modified by weight loss. However, the risk reduction is affected by the age at which weight loss occurs. In general, early weight loss-that is, before puberty-is more beneficial, but there are marked disease-specific differences.

Mice lacking BCAS1, a novel myelin-associated protein, display hypomyelination, schizophrenia-like abnormal behaviors, and upregulation of inflammatory genes in the brain

The abnormal expression and function of myelin-related proteins contribute to nervous system dysfunction associated with neuropsychiatric disorders; however, the underlying mechanism of this remains unclear. We found here that breast carcinoma amplified sequence 1 (BCAS1), a basic protein abundant in the brain, was expressed specifically in oligodendrocytes and Schwann cells, and that its expression level was decreased by demyelination. This suggests that BCAS1 is a novel myelin-associated protein. BCAS1 knockout mice displayed schizophrenia-like behavioral abnormalities and a tendency toward reduced anxiety-like behaviors. Moreover, we found that the loss of BCAS1 specifically induced hypomyelination and the expression of inflammation-related genes in the brain. These observations provide a novel insight into the functional link between oligodendrocytes and inflammation and/or abnormal behaviors.

The effects of repeat traumatic brain injury on the pituitary in adolescent rats

Adolescents are one of the highest groups at risk for sustaining both traumatic brain injury (TBI) and repeat TBI (RTBI). Consequences of endocrine dysfunction following TBI have been routinely explored in adults, but studies in adolescents are limited, and show an incidence rate of endocrine dysfunction in 16-61% in patients, 1-5 years after injury. Similar to in adults, the most commonly affected axis is growth hormone (GH) and insulin-like growth hormone 1 (IGF-1). Despite TBI being the primary cause of morbidity and mortality among the pediatric population, there are currently no experimental studies specifically addressing the occurrence of pituitary dysfunction in adolescents. The present study investigated whether a sham, single injury or four repeat injuries (24 h interval) delivered to adolescent rats resulted in disruption of the GH/IGF-1 axis. Circulating levels of basal GH and IGF-1 were measured at baseline, 24 h, 72 h, 1 week, and 1 month after injury, and vascular permeability of the pituitary gland was quantified via Evans Blue dye extravasation. Changes in weight and length of animals were measured as a potential consequence of GH and IGF-1 disruption. The results from the current study demonstrate that RTBI results in significant acute and chronic decreases in circulation of GH and IGF-1, reduction in weight gain and growth, and an increase in Evans Blue dye extravasation in the pituitary compared with sham and single injury animals. RTBI causes significant disruption of the GH/IGF-1 axis that may ultimately affect normal cognitive and physical development during adolescence.

Role of growth hormone (GH) in the treatment on neural diseases: from neuroprotection to neural repair

Growth hormone (GH) is a pleiotropic hormone that exerts important functions in the control of brain development as well as in the regulation neuronal differentiation and function, together with several behavioral and psychological effects that have been linked to its modulatory actions on brain neurotransmitters. In addition, the possibility that GH may play a role on brain repair after injury has been also envisaged, and a number of reports have shown that GH administration following injury confers neuroprotection and accelerates the recovery of some neural functions. In this review we have analyzed the state of the art of GH administration in several neural diseases. Though more studies are still necessary in order to completely understand the importance of GH in these processes, the promising results obtained so far, together with the absence of untoward effects during GH therapy, encourages the development of clinical assays in order to further support the use GH treatment in neural diseases in which neuroprotection and/or neuroregeneration are involved.

The stress system in the human brain in depression and neurodegeneration

Corticotropin-releasing hormone (CRH) plays a central role in the regulation of the hypothalamic-pituitary-adrenal (HPA)-axis, i.e., the final common pathway in the stress response. The action of CRH on ACTH release is strongly potentiated by vasopressin, that is co-produced in increasing amounts when the hypothalamic paraventricular neurons are chronically activated. Whereas vasopressin stimulates ACTH release in humans, oxytocin inhibits it. ACTH release results in the release of corticosteroids from the adrenal that, subsequently, through mineralocorticoid and glucocorticoid receptors, exert negative feedback on, among other things, the hippocampus, the pituitary and the hypothalamus. The most important glucocorticoid in humans is cortisol, present in higher levels in women than in men. During aging, the activation of the CRH neurons is modest compared to the extra activation observed in Alzheimer's disease (AD) and the even stronger increase in major depression. The HPA-axis is hyperactive in depression, due to genetic factors or due to aversive stimuli that may occur during early development or adult life. At least five interacting hypothalamic peptidergic systems are involved in the symptoms of major depression. Increased production of vasopressin in depression does not only occur in neurons that colocalize CRH, but also in neurons of the supraoptic nucleus (SON), which may lead to increased plasma levels of vasopressin, that have been related to an enhanced suicide risk. The increased activity of oxytocin neurons in the paraventricular nucleus (PVN) may be related to the eating disorders in depression. The suprachiasmatic nucleus (SCN), i.e., the biological clock of the brain, shows lower vasopressin production and a smaller circadian amplitude in depression, which may explain the sleeping problems in this disorder and may contribute to the strong CRH activation. The hypothalamo-pituitary thyroid (HPT)-axis is inhibited in depression. These hypothalamic peptidergic systems, i.e., the HPA-axis, the SCN, the SON and the HPT-axis, have many interactions with aminergic systems that are also implicated in depression. CRH neurons are strongly activated in depressed patients, and so is their HPA-axis, at all levels, but the individual variability is large. It is hypothesized that particularly a subgroup of CRH neurons that projects into the brain is activated in depression and induces the symptoms of this disorder. On the other hand, there is also a lot of evidence for a direct involvement of glucocorticoids in the etiology and symptoms of depression. Although there is a close association between cerebrospinal fluid (CSF) levels of CRH and alterations in the HPA-axis in depression, much of the CRH in CSF is likely to be derived from sources other than the PVN. Furthermore, a close interaction between the HPA-axis and the hypothalamic-pituitary-gonadal (HPG)-axis exists. Organizing effects during fetal life as well as activating effects of sex hormones on the HPA-axis have been reported. Such mechanisms may be a basis for the higher prevalence of mood disorders in women as compared to men. In addition, the stress system is affected by changing levels of sex hormones, as found, e.g., in the premenstrual period, ante- and postpartum, during the transition phase to the menopause and during the use of oral contraceptives. In depressed women, plasma levels of estrogen are usually lower and plasma levels of androgens are increased, while testosterone levels are decreased in depressed men. This is explained by the fact that both in depressed males and females the HPA-axis is increased in activity, parallel to a diminished HPG-axis, while the major source of androgens in women is the adrenal, whereas in men it is the testes. It is speculated, however, that in the etiology of depression the relative levels of sex hormones play a more important role than their absolute levels. Sex hormone replacement therapy indeed seems to improve mood in elderly people and AD patients. Studies of rats have shown that high levels of cumulative corticosteroid exposure and rather extreme chronic stress induce neuronal damage that selectively affects hippocampal structure. Studies performed under less extreme circumstances have so far provided conflicting data. The corticosteroid neurotoxicity hypothesis that evolved as a result of these initial observations is, however, not supported by clinical and experimental observations. In a few recent postmortem studies in patients treated with corticosteroids and patients who had been seriously and chronically depressed no indications for AD neuropathology, massive cell loss, or loss of plasticity could be found, while the incidence of apoptosis was extremely rare and only seen outside regions expected to be at risk for steroid overexposure. In addition, various recent experimental studies using good stereological methods failed to find massive cell loss in the hippocampus following exposure to stress or steroids, but rather showed adaptive and reversible changes in structural parameters after stress. Thus, the HPA-axis in AD is only moderately activated, possibly due to the initial (primary) hippocampal degeneration in this condition. There are no convincing arguments to presume a causal, primary role for cortisol in the pathogenesis of AD. Although cortisol and CRH may well be causally involved in the signs and symptoms of depression, there is so far no evidence for any major irreversible damage in the human hippocampus in this disorder.

Long-Term Challenges in Growth Hormone Treatment

Growth hormone deficiency (GHD) is defined biochemically as a response to hypoglycaemia with a peak GH concentration of less than 5 microg/l. The 'GHD syndrome' is a range of psychological and physical symptoms that are associated with GHD, which include increased central adiposity, decreased bone mineral density, abnormal lipid profiles, decreased cardiovascular performance, reduced lean body mass (LBM), social isolation, depressed mood and increased anxiety. Importantly, the combination of physical and psychological problems can often result in a reduced quality of life. A number of trials have shown that GH replacement therapy can lead to a substantial improvement in GHD associated symptoms. Following up to 12 months of treatment with GH, LBM increased, left ventricular systolic function improved and the mean volume of adipose tissue fell. After only 4 months of treatment, a rise in exercise capacity was recorded, and after 2 years' treatment, isokinetic and isometric muscle strength had normalized in proximal muscle groups. Feelings of well-being and vitality also improved significantly. However, studies on the effects of treatment on insulin sensitivity in GH-deficient patients have had conflicting results. In this paper, we will discuss the long-term consequences of GHD and the effects of GH replacement therapy.

A preliminary study of baclofen-induced growth hormone release in generalised social phobia

OBJECTIVE

The authors sought to examine central GABA(B) receptor responses in patients with generalised social phobia using the growth hormone (GH) response to baclofen.

METHOD

Baclofen 20 mg was administered to 15 patients and 15 healthy matched controls and plasma growth hormone was monitored over a 3 h period.

RESULTS

The GH response in patients was significantly reduced in comparison to that of controls when calculated as both area under the curve (AUC) and delta (Delta) response.

CONCLUSIONS

The results suggest an abnormality of central GABA(B) receptor function in this disorder.

Neural growth hormone: an update

It is now well established that growth hormone (GH) gene expression is not restricted to the pituitary gland and occurs in many extrapituitary tissues, including the central and peripheral nervous systems. Indeed, GH gene expression occurs in the brain prior to its ontogenic appearance in the pituitary gland, and GH may have evolved phylogenetically as a neuropeptide, rather than as an endocrine. Recent studies on the regulation and roles of neural GH in health and disease are the focus of this brief review.

The social anxiety spectrum

Social anxiety disorder is well suited to the spectrum concept because it has trait-like qualities of early onset, chronicity, and no empirically derived threshold that demarcates normal from clinically significant trait social anxiety. Social anxiety disorder has been shown to respond to relatively specific pharmacologic and cognitive-behavioral therapies, which makes identification of other conditions that may lie on the social anxiety disorder spectrum important because of possible treatment implications. Biologic markers associated with social anxiety disorder also may be shared by similar but nonidentical traits, such as behavioral inhibition and detachment. Clarification of the trait spectrums associated with specific biologic systems offers an opportunity for improving the understanding of the origin of these conditions. Strong evidence exists that at least some forms of shyness, avoidant personality disorder, and selective mutism lie on a social anxiety disorder spectrum. For several other disorders that share a prominent focus on social comparison, significant subgroups of patients seem to have features of social anxiety disorder. These disorders include major depression (especially the atypical subtype), body dysmorphic disorder, and eating disorders. Several other disorders marked by social dysfunction or inhibition, including substance use disorders (especially alcoholism), paranoid disorder, bipolar disorder, autism, and Asperger's disorder, also may show some overlap with social anxiety disorder features (e.g., social anxiety as a cause or complication of substance abuse, social avoidance in paranoid disorder, social disinhibiton in bipolar disorder, and social communication deficits in autism and Asperger's disorder). Social anxiety disorder also is associated with other anxiety disorders in general and other phobias in particular. In respect to traits, a growing body of evidence links behavioral inhibition to the unfamiliar to a social anxiety disorder spectrum with some specificity. Biologic measures of dopamine system hypoactivity have been linked to social anxiety disorder, trait detachment, and general deficits in reward and incentive function. It remains to be clarified, however, whether this brain system function is best characterized by a social anxiety disorder spectrum or some variant that incorporates social reward deficits or social avoidance behavior. Social anxiety disorder, shyness, and behavioral inhibition all seem to have a genetic component, but more research is needed to attempt to identify a more specifically heritable temperament associated with these conditions. Finally, the emergent concept of a social anxiety spectrum needs maturation. Although the notion of a single social anxiety disorder spectrum currently has some clinical use, the authors believe that exclusive focus on the notion of a single continuum with two extremes--from social disinhibition in mania to the most severe form of social anxiety, avoidant personality disorder--is premature and limiting in respect to etiologic research. An alternative approach is to conceptualize multiple, probably overlapping spectra in this area of social psychopathology. Individual dimensions might be based on various core phenomenologic, cognitive, or biologic characteristics. A bottom-up biologic approach holds promise for identifying spectra with a common etiology that might respond to specific treatments. Taking a pluralistic view of the concept of spectrum at this stage may help accelerate our understanding of social anxiety and related disorders.

Quality of life and self-esteem in children treated for idiopathic short stature

OBJECTIVE

Changes in health-related quality of life (HRQOL) and self-esteem were studied in children with idiopathic short stature (ISS) participating in a study on the effect of growth hormone treatment.

STUDY DESIGN

Prepubertal children (n = 36) with ISS were randomly assigned to a treatment or control group. Children with ISS, their parents, and the pediatrician completed HRQOL and self-esteem questionnaires 3 times in 2 years.

RESULTS

At the start, children with ISS did not have lower scores than the norm population, except for social functioning HRQOL. The pediatrician reported an improvement of HRQOL in the treatment group, the parents reported no change, and the children in the treatment group reported the same, or sometimes even worse, HRQOL or self-esteem than the control group. Changes related to the child's satisfaction with height and hardly to growth itself.

CONCLUSION

The assumption that growth hormone treatment improves HRQOL in children with ISS could not be supported in this study.

Growth hormone in the brain: characteristics of specific brain targets for the hormone and their functional significance

During the past decade studies have shown that growth hormone (GH) may exert profound effects on the central nervous system (CNS). For instance, GH replacement therapy was found to improve the psychological capabilities in adult GH deficient (GHD) patients. Furthermore, beneficial effects of the hormone on certain functions, including memory, mental alertness, motivation, and working capacity, have been reported. Likewise, GH treatment of GHD children has been observed to produce significant improvement in many behavioral problems seen in these individuals. Studies also indicated that GH therapy affects the cerebrospinal fluid levels of various hormones and neurotransmitters. Further support that the CNS is a target for GH emerges from observations indicating that the hormone may cross the blood-brain barrier (BBB) and from studies confirming the presence of GH receptors in the brain. It was previously shown that specific binding sites for GH are present in discrete areas in the CNS of both humans and rats. Among these regions are the choroid plexus, hippocampus, hypothalamus, and spinal cord. The density of GH binding in the various brain regions was found to decline with increasing age. More recently, we were able to clone and determine the structure of several GH receptors in the rat and human brain. Although the brain receptor proteins for the hormone were shown to differ in molecular size compared to those present in peripheral tissues the corresponding transcripts did not seem to differ from their peripheral congeners. GH receptors in the hypothalamus are likely to be involved in the regulatory mechanism for hormone secretion and those located in the choroid plexus have been suggested to have a role in the receptor-mediated transport of GH across the BBB. The functions mediated by the GH receptors identified in the hippocampus are not yet known but recently it was speculated that they may be involved in the hormone's action on memory and cognitive functions.

Continuation of growth hormone (GH) replacement in GH-deficient patients during transition from childhood to adulthood: a two-year placebo-controlled study

Previous studies have demonstrated beneficial effects of GH replacement, in adults with GH deficiency (GHD), on body composition, physical fitness, and quality of life. These studies, however, concern patients with adult-onset GHD or childhood-onset (CO) patients enrolled several years after withdrawal of initial therapy. So far, the effects of continuation of GH-administration in patients with CO-GHD have not been examined. We studied a group of nineteen young adults (13 males + 6 females; 16-26 yr old; mean age, 20.2 +/- 0.65 yr) with CO-GHD, in a randomized, parallel, double-blind, placebo-controlled trial for 1 yr, followed by an open phase with GH for 1 yr. All patients received GH therapy at the start of study, and trial medication (GH/placebo) was given in a similar dose. Patients randomized to continued GH treatment exhibited no significant changes in any parameters tested, but intra- and interindividual variations in insulin-like growth factor (IGF)-I levels could suggest compliance problems. Discontinuation of GH for 1 yr resulted in a decrease in serum IGF-I, from 422.0 +/- 56.8 to 147.8 +/- 33.4 microg/L, in the placebo group (P = 0.003). After discontinuation of GH for 1 yr, an increase in total body fat (TBF, kg), measured by dual-energy x-ray absorptiometry scan, was seen [placebo: 22.7 +/- 2.7 to 26.5 +/- 2.5 (P = 0.01); GH: 16.2 +/- 2.1 to 17.2 +/- 2.1 (not significant)]. Resumption of GH after placebo was followed by increments in serum IGF-I (microg/L) [from 147.8 +/- 33.4 to 452 +/- 76 (P = 0.001)] and IGF-binding protein 3, as well as in fasting glucose (mmol/L) [4.9 +/- 0.2 vs. 5.3 +/- 0.2 (P = 0.03)]. After resumption of GH lean body mass (kg) increased [52.4 +/- 4.9 vs. 60.7 +/- 5.6 (P = 0.006)]. Likewise, resumption of GH therapy increased thigh muscle volume and thigh muscle/fat ratio, as assessed by computed tomography [muscle volume (cm2/10 mm): 118.2 +/- 11.7 vs. 130.0 +/- 10.9 (P = 0.002); muscle/fat ratio: 1.33 +/- 0.24 vs. 1.69 +/- 0.36 (P = 0.02)]. In conclusion, discontinuation of GH treatment in GHD patients, during the transition from childhood to adulthood, induces significant and potentially unfavorable changes in IGF-I and body composition, both of which are reversed after resumption of GH treatment. By contrast, continuation of GH therapy results in unaltered IGF-I and body composition. We recommend continuation of GH therapy in these patients, to be undertaken in collaboration between pediatricians and adult endocrinologists.

Psychosocial outcome in growth hormone deficient patients diagnosed during childhood

Social disabilities have been described in GHD patients. The aim of this study was to evaluate the social outcome of a group of adult hypopituitary patients diagnosed and treated during childhood. Seventy patients were interviewed at a mean age of 25.6 years (range 18-50 yr). They answered a semistructured questionnaire and the Beck Depression Inventory test. Patients were compared for academic achievement, marital status and employment with the nearest age sibling. We found high levels of school repeaters, school was often not completed, and around 50% were overprotected by teachers and teased by peers. 32% were unemployed, while 58% of those employed work with their families. 80% still live with their parents; only 16% are married and 9% have children. 44% had no dating experience and 52% had never had sexual intercourse. Depression was common, especially in hypogonadic subjects. Juvenilization was the most common complaint. We did not found differences in maximal educational achievements and levels of employment between patients and siblings, but significantly more married siblings were found. Depression, social isolation and dependent life style were found in GHD patients. Appropriate medical and psychological counseling should be included for patients and their families as part of treatment.

Neurobiological perspectives on social phobia: from affiliation to zoology

Social phobia (or "social anxiety disorder") is a prevalent condition that has been the subject of increased scrutiny in recent years. The purpose of this paper is to review the neurobiology of social phobia. It is apparent from the extant literature that this disorder is poorly understood from a neurobiological perspective. There are nonetheless a number of clinical and preclinical observations which, at times, converge to illuminate areas worthy of further study. Included in this category are suggestive findings of central serotonergic dysregulation in social phobia, response to serotonin reuptake inhibitors in social phobia, and the role of serotonergic function in septohippocampal models of anxiety. Abnormalities in central dopaminergic function are also posited, supported to some extent by recent neuroimaging findings. There are in addition a number of animal and human behavioral models in existence that may be relevant to the study of social phobia. Included in this category are models of social dominance in wild baboons, social affiliation in the prairie vole, and behavioral inhibition to the unfamiliar in childhood. Newer technologies that are likely to play a major role in the delineation of the neural circuitry (e.g., functional magnetic resonance imaging) and heritability (e.g., molecular genetics) of social phobia are discussed. Finally, an interactive role for biology and experience in the expression of social phobia is considered.

Effects of physiological growth hormone (GH) therapy on cognition and quality of life in patients with adult-onset GH deficiency

GH replacement of adults with acquired GH deficiency (GHD) results in body composition changes including increases in lean mass and bone mineral density. However, the effects of long-term GH therapy on cognitive function are largely unknown, and there are conflicting data regarding quality of life. We performed a randomized, double-blind, placebo-controlled study of GH replacement in adults with GHD and measured cognition and sense of well-being using standardized psychometric tests before and after therapy. Forty men (median age 51 yr, range 24-64 yr) with a history of pituitary disease were randomized to GH therapy (starting dose, 10 +/- 0.3 micrograms/kg per day: mean treatment dose, 4 +/- 2 micrograms/kg per day) vs. placebo for 18 months, and GH doses were adjusted according to serum insulin growth factor-I levels. At baseline, the patients displayed a full-scale intelligence quotient (IQ) score nearly 1 SD above the normal mean. Mean scores on all cognitive tests fell within normal limits, and on many tests, fell above the mean. On tests of verbal learning and delayed visual memory, mean test scores fell below the mean (although within normal limits), suggestive of a relative compromise in the area of memory performance. Following 18 months of GH replacement therapy, there were no significant changes in cognitive function or quality of life. We conclude that acquired GHD in adult men is not associated with significant alterations in cognitive function as assessed by standardized tests, and chronic low-dose GH replacement therapy does not result in significant beneficial effects on cognitive function or quality of life. Although previous studies have suggested that GH replacement in adults with acquired GHD may improve quality of life, our data do not support the use of physiological GH replacement in GHD men for this indication.

Psychoneuroendocrinology of children and adolescents

This article reviews psychoneuroendocrinologic approaches to the understanding of internalizing disorders (depression and anxiety disorders) and externalizing disorders. This article discusses three specific psychoneuroendocrine systems: measures of the hypothalamic-pituitary-adrenal (HPA) axis, measure of the serotonergic function, and measures of the growth-hormone (GH) response to pharmacologic challenge. The hypothalamic-pituitary-adrenal (HPA) axis is the main system; understanding this system may reveal information on the permissive and etiologic relationship of stress to psychiatric disorder.