Increased locomotor and thermogenic activity in mice with targeted ablation of the GHRH gene

Neuroendocrine control of brown adipocyte function by prolactin and growth hormone

Growth hormone (GH) is fundamental for growth and glucose homeostasis, and prolactin for optimal pregnancy and lactation outcome, but additionally, both hormones have multiple functions that include a strong impact on energetic metabolism. In this respect, prolactin and GH receptors have been found in brown, and white adipocytes, as well as in hypothalamic centers regulating thermogenesis. This review describes the neuroendocrine control of the function and plasticity of brown and beige adipocytes, with a special focus on prolactin and GH actions. Most evidence points to a negative association between high prolactin levels and the thermogenic capacity of BAT, except in early development. During lactation and pregnancy, prolactin may be a contributing factor that limits unneeded thermogenesis, downregulating BAT UCP1. Furthermore, animal models of high serum prolactin have low BAT UCP1 levels and whitening of the tissue, while lack of Prlr induces beiging in WAT depots. These actions may involve hypothalamic nuclei, particularly the DMN, POA and ARN, brain centers that participate in thermogenesis. Studies on GH regulation of BAT function present some controversies. Most mouse models with GH excess or deficiency point to an inhibitory role of GH on BAT function. Even so, a stimulatory role of GH on WAT beiging has also been described, in accordance with whole-genome microarrays that demonstrate divergent response signatures of BAT and WAT genes to the loss of GH signaling. Understanding the physiology of BAT and WAT beiging may contribute to the ongoing efforts to curtail obesity.

Common and uncommon mouse models of growth hormone deficiency

Mouse models of growth hormone deficiency (GHD) have provided important tools for uncovering the various actions of GH. Nearly 100 years of research using these mouse lines has greatly enhanced our knowledge of the GH/IGF-1 axis. Some of the shared phenotypes of the five "common" mouse models of GHD include reduced body size, delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, and enhanced insulin sensitivity. Since these common mouse lines outlive their normal-sized littermates - and have protection from age-associated disease - they have become important fixtures in the aging field. On the other hand, the twelve "uncommon" mouse models of GHD described herein have tremendously divergent health outcomes ranging from beneficial aging phenotypes (similar to those described for the common models) to extremely detrimental features (such as improper development of the CNS, numerous sensory organ defects, and embryonic lethality). Moreover, advancements in next generation sequencing technologies have led to the identification of an expanding array of genes that are recognized as causative agents to numerous rare syndromes with concomitant GHD. Accordingly, this review provides researchers with a comprehensive up-to-date collection of the common and uncommon mouse models of GHD that have been used to study various aspects of physiology and metabolism associated with multiple forms of GHD. For each mouse line presented, the closest comparable human syndromes are discussed providing important parallels to the clinic.

Effects of GHRH Deficiency and GHRH Antagonism on Emotional Disorders in Mice

Growth hormone (GH)-releasing hormone (GHRH) has been suggested to play a crucial role in brain function. We aimed to further investigate the effects of a novel GHRH antagonist of the Miami (MIA) series, MIA-602, on emotional disorders and explore the relationships between the endocrine system and mood disorders. In this context, the effects induced by MIA-602 were also analyzed in comparison to vehicle-treated mice with GH deficiency due to generalized ablation of the GHRH gene (GHRH knock out (GHRHKO)). We show that the chronic subcutaneous administration of MIA-602 to wild type (+/+) mice, as well as generalized ablation of the GHRH gene, is associated with anxiolytic and antidepressant behavior. Moreover, immunohistochemical and Western blot analyses suggested an evident activation of Nrf2, HO1, and NQO1 in the prefrontal cortex of both +/+ mice treated with MIA-602 (+/+ MIA-602) and homozygous GHRHKO (-/- control) animals. Finally, we also found significantly decreased COX-2, iNOS, NFkB, and TNF-α gene expressions, as well as increased P-AKT and AKT levels in +/+ MIA-602 and -/- control animals compared to +/+ mice treated with vehicle (+/+ control). We hypothesize that the generalized ablation of the GHRH gene leads to a dysregulation of neural pathways, which is mimicked by GHRH antagonist treatment.

Mice with gene alterations in the GH and IGF family

Much of our understanding of GH's action stems from animal models and the generation and characterization of genetically altered or modified mice. Manipulation of genes in the GH/IGF1 family in animals started in 1982 when the first GH transgenic mice were produced. Since then, multiple laboratories have altered mouse DNA to globally disrupt Gh, Ghr, and other genes upstream or downstream of GH or its receptor. The ability to stay current with the various genetically manipulated mouse lines within the realm of GH/IGF1 research has been daunting. As such, this review attempts to consolidate and summarize the literature related to the initial characterization of many of the known gene-manipulated mice relating to the actions of GH, PRL and IGF1. We have organized the mouse lines by modifications made to constituents of the GH/IGF1 family either upstream or downstream of GHR or to the GHR itself. Available data on the effect of altered gene expression on growth, GH/IGF1 levels, body composition, reproduction, diabetes, metabolism, cancer, and aging are summarized. For the ease of finding this information, key words are highlighted in bold throughout the main text for each mouse line and this information is summarized in Tables 1, 2, 3 and 4. Most importantly, the collective data derived from and reported for these mice have enhanced our understanding of GH action.

Effects of growth hormone-releasing hormone receptor antagonist MIA-602 in mice with emotional disorders: a potential treatment for PTSD

Anxiety and depression have been suggested to increase the risk for post-traumatic stress disorders (PTSD). A link between all these mental illnesses, inflammation and oxidative stress is also well established. Recent behavior studies by our group clearly demonstrate a powerful anxiolytic and antidepressant-like effects of a novel growth hormone releasing hormone (GHRH) antagonist of MIAMI class, MIA-690, probably related to modulatory effects on the inflammatory and oxidative status. In the present work we investigated the potential beneficial effects of MIA-602, another recently developed GHRH antagonist, in mood disorders, as anxiety and depression, and the possible brain pathways involved in its protective activity, in adult mice. MIA-602 exhibited antinflammatory and antioxidant effects in ex vivo and in vivo experimental models, inducing anxiolytic and antidepressant-like behavior in mice subcutaneously treated for 4 weeks. The beneficial effect of MIA-602 on inflammatory and oxidative status and synaptogenesis resulting in anxiolytic and antidepressant-like effects could be related by increases of nuclear factor erythroid 2-related factor 2 (Nrf2) and of brain-derived neurotrophic factor (BDNF) signaling pathways in the hippocampus and prefrontal cortex. These results strongly suggest that GHRH analogs should be tried clinically for the treatment of mood disorders including PTSD.

Growth hormone-releasing hormone antagonistic analog MIA-690 stimulates food intake in mice

In addition to its metabolic and endocrine effects, growth hormone-releasing hormone (GHRH) was found to modulate feeding behavior in mammals. However, the role of recently synthetized GHRH antagonist MIA-690 and MR-409, a GHRH agonist, on feeding regulation remains to be evaluated. We investigated the effects of chronic subcutaneous administration of MIA-690 and MR-409 on feeding behavior and energy metabolism, in mice. Compared to vehicle, MIA-690 increased food intake and body weight, while MR-409 had no effect. Both analogs did not modify locomotor activity, as well as subcutaneous, visceral and brown adipose tissue (BAT) mass. A significant increase of hypothalamic agouti-related peptide (AgRP) gene expression and norepinephrine (NE) levels, along with a reduction of serotonin (5-HT) levels were found after MIA-690 treatment. MIA-690 was also found able to decrease gene expression of leptin in visceral adipose tissue. By contrast, MR-409 had no effect on the investigated markers. Concluding, chronic peripheral administration of MIA-690 could play an orexigenic role, paralleled by an increase in body weight. The stimulation of feeding could be mediated, albeit partially, by elevation of AgRP gene expression and NE levels and decreased 5-HT levels in the hypothalamus, along with reduced leptin gene expression, in the visceral adipose tissue.

Protective Effects Induced by a Hydroalcoholic Allium sativum Extract in Isolated Mouse Heart

The aim of the present study was to investigate the possible protective effects of a garlic hydroalcoholic extract on the burden of oxidative stress and inflammation occurring on mouse heart specimens exposed to E. coli lipopolysaccharide (LPS), which is a well-established inflammatory stimulus. Headspace solid-phase microextraction combined with the gas chromatography-mass spectrometry (HS-SPME/GC-MS) technique was applied to determine the volatile fraction of the garlic powder, and the HS-SPME conditions were optimized for each of the most representative classes of compounds. CIEL*a*b* colorimetric analyses were performed on the powder sample at the time of delivery, after four and after eight months of storage at room temperature in the dark, to evaluate the color changing. Freshly prepared hydroalcoholic extract was also evaluated in its color character. Furthermore, the hydroalcoholic extract was analyzed through GC-MS. The extract was found to be able to significantly inhibit LPS-induced prostaglandin (PG) E₂ and 8-iso-PGF_2α levels, as well as mRNA levels of cyclooxygenase (COX)-2, interleukin (IL)-6, and nuclear factor-kB (NF-kB), in heart specimens. Concluding, our findings showed that the garlic hydroalcoholic extract exhibited cardioprotective effects on multiple inflammatory and oxidative stress pathways.

Mouse models of growth hormone deficiency

Nearly one century of research using growth hormone deficient (GHD) mouse lines has contributed greatly toward our knowledge of growth hormone (GH), a pituitary-derived hormone that binds and signals through the GH receptor and affects many metabolic processes throughout life. Although delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, small body size, and glucose intolerance appear to be among the negative characteristics of these GHD mouse lines, these mice still consistently outlive their normal sized littermates. Furthermore, the absence of GH action in these mouse lines leads to enhanced insulin sensitivity (likely due to the lack of GH's diabetogenic actions), delayed onset for a number of age-associated physiological declines (including cognition, cancer, and neuromusculoskeletal frailty), reduced cellular senescence, and ultimately, extended lifespan. In this review, we provide details about history, availability, growth, physiology, and aging of five commonly used GHD mouse lines.

Protective effects of growth hormone-releasing hormone analogs in DSS-induced colitis in mice

Besides its metabolic and endocrine effects, growth hormone (GH)-releasing hormone (GHRH) is involved in the modulation of inflammation. Recently synthetized GHRH antagonist MIA-690 and MR-409, GHRH agonist, developed by us have shown potent pharmacological effects in various experimental paradigms. However, whether their administration modify resistance to chronic inflammatory stimuli in colon is still unknown. Ex vivo results demonstrated that MIA-690 and MR-409 inhibited production of pro-inflammatory and oxidative markers induced by lipopolysaccharide on isolated mouse colon specimens. In vivo, both MIA-690 and MR-409 have also been able to decrease the responsiveness to nociceptive stimulus, in hot plate test. Additionally, both peptides also induced a decreased sensitivity to acute and persistent inflammatory stimuli in male mice, in formalin test and dextran sodium sulfate (DSS)-induced colitis model, respectively. MIA-690 and MR-409 attenuate DSS-induced colitis with particular regard to clinical manifestations, histopathological damage and release of pro-inflammatory and oxidative markers in colon specimens. Respect to MR-409, MIA-690 showed higher efficacy in inhibiting prostaglandin (PG)E₂, 8-iso-PGF_2α and serotonin (5-HT) levels, as well as tumor necrosis factor (TNF)-α, interleukin (IL)-6 and nitric oxide synthase gene expression in colon specimens of DSS-induced colitis. Furthermore, MIA-690 decreased serum insulin-like growth factor (IGF)-1 levels in mice DSS-treated, respect to MR-409. Thus, our findings highlight the protective effects of MIA-690 and MR-409 on inflammation stimuli. The higher antinflammatory and antioxidant activities observed with MIA-690 could be related to decreased serum IGF-1 levels.

Multidirectional Pharma-Toxicological Study on Harpagophytum procumbens DC. ex Meisn.: An IBD-Focused Investigation

In the present study, we investigated the water extract of Harpagophytum procumbens DC. ex Meisn. in an experimental model of inflammatory bowel diseases (IBDs). Additionally, a microbiological investigation was carried out to discriminate the efficacy against bacterial and fungal strains involved in IBDs. Finally, an untargeted proteomic analysis was conducted on more than one hundred colon proteins involved in tissue morphology and metabolism. The extract was effective in blunting the production of oxidative stress and inflammation, including serotonin, prostaglandins, cytokines, and transcription factors. Additionally, the extract inhibited the growth of Candida albicans and C. tropicalis. The extract was also able to exert a pro-homeostatic effect on the levels of a wide plethora of colon proteins, thus corroborating a protective effect. Conversely, the supraphysiological downregulation of cytoskeletal-related proteins involved in tissue morphology and antimicrobial barrier function suggests a warning in the use of food supplements containing H. procumbens extracts.

Antinflammatory, antioxidant, and behavioral effects induced by administration of growth hormone-releasing hormone analogs in mice

Growth hormone-releasing hormone (GHRH) antagonist MIA-690 and GHRH agonist MR-409, previously synthesized and developed by us have demonstrated potent antitumor effects. However, little is known about the effects of these analogs on brain functions. We investigated the potential antinflammatory and antioxidant effects of GHRH antagonist MIA-690 and GHRH agonist MR-409, on isolated mouse prefrontal cortex specimens treated with lipopolysaccharide (LPS). Additionally, we studied their effects on emotional behavior after chronic in vivo treatment. Ex vivo, MIA-690 and MR-409 inhibited LPS-induced inflammatory and pro-oxidative markers. In vivo, both MIA-690 and MR-409 induced anxiolytic and antidepressant-like effects, increased norepinephrine and serotonin levels and decreased nuclear factor-kB, tumor necrosis factor-α and interleukin-6 gene expression in prefrontal cortex. Increased nuclear factor erythroid 2–related factor 2 expression was also found in mice treated with MIA-690 and MR-409. MIA-690 showed higher efficacy in inhibiting all tested inflammatory and oxidative markers. In addition, MR-409 induced a down regulation of the gene and protein expression of pituitary-type GHRH-receptor in prefrontal cortex of mice after 4 weeks of treatment at 5 µg/day. In conclusion, our results demonstrate anxiolytic and antidepressant-like effects of GHRH analogs that could involve modulatory effects on monoaminergic signaling, inflammatory and oxidative status.

Growth hormone-releasing hormone (GHRH) deficiency promotes inflammation-associated carcinogenesis

The somatotropic axis, in addition to its well-known metabolic and endocrine effects, plays a pivotal role in modulation of inflammation. Moreover, growth hormone (GH)-releasing hormone (GHRH) has been involved in the development of various human tumors. In this work we aimed to investigate the consequences of GHRH deficiency on the development of inflammation-associated colon carcinogenesis in a mouse model of isolated GH deficiency due to generalized ablation of the GHRH gene [GHRH knock out (GHRHKO)]. Homozygous GHRHKO (-/-) male mice and wild type (C57/BL6, +/+) male mice as control group, were used. After azoxymetane (AOM)/dextran sodium sulfate (DSS) treatment -/- mice displayed higher Disease Activity Index (DAI) score, and more marked weight loss compared to +/+ animals. Additionally, -/- mice showed a significant increase in total tumors, in particular of large size predominantly localized in distal colon. In colonic tissue of AOM/DSS-treated -/- mice we found the presence of invasive adenocarcinomas, dysplasia and colitis with mucosal ulceration. Conversely, AOM/DSS-treated +/+ mice showed only presence of adenomas, without invasion of sub-mucosa. Treatment with AOM/DSS significantly increased prostaglandin (PG)E₂ and 8-iso-PGF_2α levels along with cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF)-α, nuclear factor kappa B (NF-kB) and inducible nitric oxide synthase (iNOS) gene expression, in colon specimens. The degree of increase of all these parameters was more markedly in -/- than +/+ mice. In conclusion, generalized GHRH ablation increases colon carcinogenesis responsiveness in male mice. Whether this results from lack of GH or GHRH remains to be established.

Protective Effects Induced by Two Polyphenolic Liquid Complexes from Olive (Olea europaea, mainly Cultivar Coratina) Pressing Juice in Rat Isolated Tissues Challenged with LPS

MOMAST^(®) HY100 and MOMAST^(®) HP30 are polyphenolic liquid complexes from olive pressing juice with a total polyphenolic content of 100 g/kg (at least 50% as hydroxytyrosol) and 36 g/kg (at least 30% as hydroxytyrosol), respectively. We investigated the potential protective role of MOMAST^(®) HY100 and MOMAST^(®) HP30 on isolated rat colon, liver, heart, and prefrontal cortex specimens treated with Escherichia coli lipopolysaccharide (LPS), a validated ex vivo model of inflammation, by measuring the production of prostaglandin (PG)E₂, 8-iso-PGF_2α, lactate dehydrogenase (LDH), as well as cyclooxygenase (COX)-2, tumor necrosis factor α (TNFα), and inducible nitric oxide synthase (iNOS) mRNA levels. MOMAST^(®) HY100 decreased LPS-stimulated PGE₂ and LDH levels in all tested tissues. Following treatment with MOMAST^(®) HY100, we found a significant reduction in iNOS levels in prefrontal cortex and heart specimens, COX-2 and TNFα mRNA levels in heart specimens, and 8-iso-PGF_2α levels in liver specimens. On the other hand, MOMAST^(®) HP30 was found to blunt COX-2, TNFα, and iNOS mRNA levels, as well as 8-iso-PGF_2α in cortex, liver, and colon specimens. MOMAST^(®) HP30 was also found to decrease PGE₂ levels in liver specimens, while it decreased iNOS mRNA, LDH, and 8-iso-PGF_2α levels in heart specimens. Both MOMAST^(®) HY100 and MOMAST^(®) HP30 exhibited protective effects on multiple inflammatory and oxidative stress pathways.

Increased pain and inflammatory sensitivity in growth hormone-releasing hormone (GHRH) knockout mice

Growth hormone (GH) and GH-releasing hormone (GHRH), in addition to metabolic and endocrine effects, play a role in the modulation of pain and inflammation. We aimed to elucidate the consequences of GHRH deficiency on acute nociceptive stimulation and on both acute and chronic inflammatory stimuli in a mouse model of GH deficiency. Mice with generalized ablation of the GHRH gene (GHRH knock out, GHRHKO, -/-) were compared to wild type (GHRH +/+) mice. Responsiveness to acute nociceptive stimulation and to acute inflammatory stimulation was evaluated by conventional hot plate apparatus and formalin test, respectively. We also evaluated responsiveness to colonic inflammation induced both in vivo, after dextran sodium sulfate (DSS) treatment, or ex vivo, by incubating colon segments with bacterial lipopolysaccaride (LPS). Macroscopical and histological examinations were performed, prostaglandin (PG) E₂ and 8-iso-PGF_2α levels and cyclooxigenase (COX)-2 and tumor necrosis factor (TNF)-α gene expression were measured. Compared to controls, -/- mice showed decreased response latency during the hot plate test, and increased licking/biting time in formalin test, particularly in the second phase of inflammation. DSS treated -/- mice showed a significant increase of colonic inflammation compared to controls. Moreover DSS treatment increased PGE₂ and 8-iso-PGF_2α levels, along with COX-2 and TNF-α gene expression more markedly in colon specimens of -/- mice compared to controls. LPS-induced PGE₂ and 8-iso-PGF_2α production from colonic segments incubated ex vivo was also increased in -/- mice. Generalized GHRH gene ablation increases sensitivity to thermal pain and both acute and persistent inflammatory stimuli in male mice.

Walking and postural balance in adults with severe short stature due to isolated GH deficiency

OBJECTIVES

Walking and postural balance are extremely important to obtain food and to work. Both are critical for quality of life and ability to survive. While walking reflects musculoskeletal and cardiopulmonary systems, postural balance depends on body size, muscle tone, visual, vestibular and nervous systems. Since GH and IGF-I act on all these systems, we decided to study those parameters in a cohort of individuals with severe short stature due to untreated isolated GH deficiency (IGHD) caused by a mutation in the GHRH receptor gene. These IGHD subjects, despite reduction in muscle mass, are very active and have normal longevity.

METHODS

In a cross-sectional study, we assessed walking (by a 6-min walk test), postural balance (by force platform) and fall risk (by the 'Timed Up and Go' test) in 31 IGHD and 40 matched health controls.

RESULTS

The percentage of the walked distance measured in relation to the predicted one was similar in groups, but higher in IGHD, when corrected by the leg length. Absolute postural balance data showed similar velocity of unipodal support in the two groups, and better values, with open and closed eyes and unipodal support, in IGHD, but these differences became non-significant when corrected for height and lower-limb length. The time in 'Timed Up and Go' test was higher in IGHD cohort, but still below the cut-off value for fall risk.

CONCLUSION

IGHD subjects exhibit satisfactory walking and postural balance, without increase in fall risk.

Adult individuals with congenital, untreated, severe isolated growth hormone deficiency have satisfactory muscular function

PURPOSE

While growth hormone (GH) and the insulin-like growth factor type I (IGF-I) are known to exert synergistic actions on muscle anabolism, the consequences of prolonged GH deficiency (GHD) on muscle function have not been well defined. We have previously described a large cohort of subjects with isolated GHD (IGHD) caused by a mutation in the GH-releasing hormone receptor gene, with low serum levels of GH and IGF-I. The aim of this study was to assess muscular function in these IGHD subjects.

METHODS

A total of 31 GH-naïve IGHD (16 males) and 40 control (20 males) subjects, matched by age and degree of daily physical activity, were enrolled. Fat free mass was measured by bioelectrical impedance; muscle strength by dynamometry of handgrip, trunk extension, and knee extension; myoelectric activity and muscle fatigue by fractal dimension; conduction velocity in vastus medialis, rectus femoris, and vastus lateralis muscles by surface electromyography.

RESULTS

The IGHD group showed higher knee extension strength both when corrected for weight and fat free mass, and higher handgrip and trunk extension strength corrected by fat free mass. They also exhibit higher conduction velocity of the muscles vastus medialis, rectus femoris, and vastus lateralis, but lower free fat mass and myoelectric activity of the vastus medialis, rectus femoris and vastus lateralis. There were no differences between the two groups in fractal dimension in all studied muscles.

CONCLUSION

Individuals with untreated IGHD have better muscle strength parameters adjusted for weight and fat free mass than controls. They also exhibit greater peripheral resistance to fatigue, demonstrating satisfactory muscle function.

Effects of RVD-hemopressin (α) on feeding and body weight after standard or cafeteria diet in rats

Palatability and variety of foods are major reasons for hedonic eating, and hence for obesity. Hemopressin, a hemoglobin α chain-derived peptide, plays antagonist/inverse agonist role on cannabinoid (CB)1 receptors, while RVD-hemopressin(α)[RVD-hp(α)], a N-terminally extended form of hemopressin, has been reported as an allosteric modulator of CB1 and CB2 receptors. We investigated the effects of 14 daily intraperitoneal injections of RVD-hp(α), in Sprague-Dawley rats fed a highly palatable cafeteria-style (CAF) diet (30% fat, 56% carbohydrate, 14% protein; 4.20 kcal/g) compared to standard laboratory chow (STD) food (3.5% fat, 63% carbohydrate, 14% protein, 19.5% other components without caloric value; 3.20 kcal). Food intake, body weight and locomotor activity were recorded throughout the study. Finally, rats were sacrificed and agouti-related peptide (AgRP), neuropeptide Y (NPY), pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) and fatty acid amide hydrolase (FAAH) gene expression in the hypothalamus was measured by real-time reverse transcription polymerase chain reaction. We found that CAF diet increased food intake as compared to STD diet. In both STD and CAF diet fed rats, RVD-hp(α) treatment inhibited food intake, increased locomotor activity but did not modify body weight. In vehicle injected animals, CAF as compared to STD diet increased AgRP gene expression. RVD-hp(α) treatment decreased POMC mRNA levels in both diet groups and lowered the elevated AgRP levels induced by CAF diet. RVD-hp(α) treatment plays an anorexigenic role paralleled by increased locomotor activity both in STD and CAF diet fed rats. The inhibition of feeding could be partially mediated by lowering of hypothalamic POMC and AgRP gene expression levels.

Behavioural phenotyping, learning and memory in young and aged growth hormone-releasing hormone-knockout mice

BACKGROUND

Growth hormone-releasing hormone (GHRH) plays an important role in brain functions. The aim of this study was to examine cognitive functions and emotional behaviour in a mouse model of isolated GH deficiency due to bi-allelic ablation of the GHRH gene (GHRH knockout, GHRHKO).

METHODS

Learning, memory and emotional behaviour were evaluated using a series of validated tests (Morris water maze, eight-arm radial maze, open field, elevated plus maze test, forced swim tests) in 2-, 5- and 12-month-old male mice either homozygous (−/−) or heterozygous (+/−) for the GHRHKO allele.

RESULTS

Compared with age-matched +/− mice, −/− mice showed decreased cognitive performance in Morris water maze and eight-arm radial maze tests. By comparing the effects of aging in each genotype, we observed an age-related impairment in test results in +/− mice, while in −/− mice a significant decline in cognitive function was found only in 12 months compared with 2-month-old mice, but no difference was found between 5 months old vs 2 months old. −/− mice showed increased exploration activity compared to age-matched +/− controls, while both strains of mice had an age-related decrease in exploration activity. When evaluated through open field, elevated plus maze and forced swim tests, −/− mice demonstrated a decrease in anxiety and depression-related behaviour compared to age-matched +/− controls.

CONCLUSIONS

Our results suggest that homozygous ablation of GHRH gene is associated with decreased performance in learning and memory tests, possibly linked to increased spontaneous locomotor activity. In addition, we observed an age-related decline in cognitive functions in both genotypes.

Effects of growth hormone on uncoupling protein 1 in white adipose tissues in obese mice

OBJECTIVE

The transition of white adipocytes to beige cells (a phenomenon referred to as browning or beigeing) during obesity has been previously reported. Our study aimed to examine the mechanisms through which obesity induced by a high fat diet (HFD) affects uncoupling protein 1 (UCP1) expression via signal transduction and activator of transcription 5 (STAT5s).

DESIGN

Seven-week-old male C57BL/6J mice were fed a normal or HFD for 11weeks. Body weight, white adipose tissue weight, and blood lipid and glucose levels were measured. To unveil the molecular mechanisms of UCP1 expression in adipose tissue, we performed further studying 3T3-L1 cells using qRT-PCR. We also measured UCP1 promoter activity in the TSA201 cell line using a dual luciferase assay. In addition, we analyzed the predicted consensus sequences for STAT5 binding in the UCP1 promoter region.

RESULTS

Mice fed an HFD had higher body weight and intra-abdominal adipose tissues weight and a higher expression of UCP1, GH receptor (GHR), STATs, suppressors of cytokine signaling (SOCSs), and cytokine-inducible SH2-containing protein (CISH) compared to control mice. In 3T3-L1 cell studies, GH induced phosphorylation of the STAT5, SOCSs, CISH and UCP1 expressions. UCP1 promoter activity was associated with constitutively active STAT5 in a dose-dependent manner. We confirmed functional STAT5 binding sites at -425, -279, and -178bp of the UCP1 promoter.

CONCLUSION

We suggest that endogenous GH induces UCP1 expression in adipose tissue via STAT5.

Dwarfism and insulin resistance in male offspring caused by α1-adrenergic antagonism during pregnancy

OBJECTIVE

Maternal and environmental factors control the epigenetic fetal programming of the embryo, thereby defining the susceptibility for metabolic or endocrine disorders in the offspring. Pharmacological interventions required as a consequence of gestational problems, e.g. hypertension, can potentially interfere with correct fetal programming. As epigenetic alterations are usually only revealed later in life and not detected in studies focusing on early perinatal outcomes, little is known about the long-term epigenetic effects of gestational drug treatments. We sought to test the consequences of maternal α1-adrenergic antagonism during pregnancy, which can occur e.g. during hypertension treatment, for the endocrine and metabolic phenotype of the offspring.

METHODS

We treated C57BL/6NCrl female mice with the α1-adrenergic antagonist prazosin during pregnancy and analyzed the male and female offspring for endocrine and metabolic abnormalities.

RESULTS

Our data revealed that maternal α1-adrenergic blockade caused dwarfism, elevated body temperature, and insulin resistance in male offspring, accompanied by reduced IGF-1 serum concentrations as the result of reduced hepatic growth hormone receptor (Ghr) expression. We subsequently identified increased CpG DNA methylation at the transcriptional start site of the alternative Ghr promotor caused by the maternal treatment, which showed a strong inverse correlation to hepatic Ghr expression.

CONCLUSIONS

Our results demonstrate that maternal α1-adrenergic blockade can constitute an epigenetic cause for dwarfism and insulin resistance. The findings are of immediate clinical relevance as combined α/β-adrenergic blockers are first-line treatment of maternal hypertension.

Models of GH deficiency in animal studies

Growth hormone (GH) is a peptide hormone released from pituitary somatotrope cells that promotes growth, cell division and regeneration by acting directly through the GH receptor (GHR), or indirectly via hepatic insulin-like growth factor 1 (IGF1) production. GH deficiency (GHD) can cause severe consequences, such as growth failure, changes in body composition and altered insulin sensitivity, depending of the origin, time of onset (childhood or adulthood) or duration of GHD. The highly variable clinical phenotypes of GHD can now be better understood through research on transgenic and naturally-occurring animal models, which are widely employed to investigate the origin, phenotype, and consequences of GHD, and particularly the underlying mechanisms of metabolic disorders associated to GHD. Here, we reviewed the most salient aspects of GH biology, from somatotrope development to GH actions, linked to certain GHD types, as well as the animal models employed to reproduce these GHD-associated alterations.

Subjects with isolated GH deficiency due to a null GHRHR mutation eat proportionally more, but healthier than controls

The GH/IGF-I axis has important interactions with the alimentary system and with the balance between energy intake (EI) and energy requirement (ER). Reduced EI has been described in adult-onset acquired GH deficiency (GHD). Individuals from the Brazilian Itabaianinha cohort, with isolated GHD (IGHD) due to a homozygous mutation (c.57+1G→A) in the GHRH receptor gene, are an ideal model to study the consequences of lifetime GHD. The purpose of this study is to evaluate EI and ER in this untreated IGHD cohort. Cross-sectional study of 24 adult IGHD patients and 23 controls from the same region, matched for age and gender. Estimated EI (EEI) was evaluated by dietary recall, and estimated ER (EER) by the equation of the Dietary Reference Intakes. Fat mass was assessed by DXA. Both EEI and EER were lower in IGHD than controls. However, when corrected by body weight, EEI was higher in IGHD (p = 0.005). IGHD individuals consume in percentage more proteins (p < 0.0001), less carbohydrates (p = 0.013), and equal amount of lipids in comparison to controls. The higher EEI per body weight suggests a possible increase of orexigenic mechanisms in untreated IGHD individuals, ensuring greater caloric intake, which would have adaptive advantages for small-sized individuals in environments with limited access to food. IGHD individuals seem to have a healthier dietary pattern than CO.