Enrique De Miguel

Antinociceptive and motor-blocking action of epidurally administered IQB-9302 and bupivacaine in the dog.

Background and Objectives The aim of this study was to compare the antinociceptive and motor-blocking effects of epidurally administered IQB-9302 (C18 H26N2O. HCl) and bupivacaine in the dog. Methods Twelve adult female Beagle dogs were used. Each animal received 3 concentrations (0.25%, 0.50%, and 0.75%) of either IQB-9302 (n = 6) or bupivacaine (n = 6) by means of a chronic epidural catheter. The nocifensive and motor-blocking status were determined at regular intervals before (baseline) and after drug administration. Results Epidurally administered IQB-9302 caused a more potent nocifensive and motor-blocking action than bupivacaine. The duration of complete nocifensive block was the longest with IQB-9302, whereas the duration of dermatome nocifensive block was similar for both drugs. The nocifensive to motor block ratio was significantly higher with IQB-9302. Conclusions IQB-9302 produced an anesthetic action similar to that of bupivacaine, although the former drug induced a slightly more potent nocifensive block. Nocifensive and motor block duration are very similar with IQB-9302, whereas bupivacaine induces a more prolonged motor block without nocifensive block.

Growth hormone plus high protein diet promotes adaptation after massive bowel resection in aged rats

OBJECTIVE To determine whether GH improves adaptation following massive bowel resection in the aged rat fed on a high protein-content diet. MATERIAL AND METHODS Seventy-seven male Wistar rats aged 22+/-1 months underwent 80% bowel resection or laparotomy (sham-operation). They were randomly placed into one of eight groups, treated with either growth hormone (1mg/kg/day) or saline, and fed a liquid diet containing either a high or a normal protein content. Intestinal tissue and blood samples were taken seven days after surgery and analysed to measure intestinal mucosal proliferation and mucosal height, as well as plasma levels of IGF-1 and somatostatin. RESULTS Resection of the small bowel in aged rats remarkably increased villous height and crypt proliferation. Growth hormone did not potentiate the increase in mucosal height and crypt proliferation observed after intestinal resection in aged rats fed a normal protein content diet, but did in those receiving a high-protein diet. Plasma levels of IGF-1 and somatostatin were not modified by surgery or treatment. CONCLUSION Growth hormone may increase the adaptation of intestinal mucosa in aged rats undergoing massive intestinal resection, but requires an adequate nutritional support with increased amounts of high quality protein.

Exogenous ghrelin regulates proliferation and apoptosis in the hypotrophic gut mucosa of the rat

Ghrelin is the natural endogenous ligand for growth hormone secretagogue receptors. This peptide regulates energy homeostasis and expenditure and is a potential link between gut absorptive function and growth. We hypothesized that ghrelin may induce a proliferative and antiapoptotic action promoting the recovery of the hypotrophic gut mucosa. Therefore, the aim of the study was to determine the action of exogenous ghrelin following gut mucosal hypotrophia in rats fed an elemental diet. An elemental diet provides readily absorbable simple nutrients and is usually given to patients with absorptive dysfunction. Male Wistar rats (n = 48) were fed the elemental diet for one week to induce mucosal hypotrophy and then treated for another week with systemic ghrelin and pair-fed with either a normoproteic or hyperproteic isocaloric liquid diet. Another group received a standard diet instead of the elemental diet and served as control (normotrophy). The elemental diet induced intestinal hypotrophia characterized by decreased proliferation in the ileum and increased apoptosis in jejunum and ileum. Ghrelin administration restored normal levels of proliferation in the ileum and apoptosis in the jejunum, with partial apoptosis restoration in the ileum. Ghrelin levels in plasma and fundus were increased in all groups, although the highest levels were found in rats treated with exogenous ghrelin. Ghrelin administration has a positive effect in the hypotrophic gut, regulating both proliferation and apoptosis towards a physiological balance counteracting the negative changes induced by an elemental diet in the intestines.

Differential action of growth hormone in irradiated tumoral and nontumoral intestinal tissue.

Growth hormone (GH) protects the intestines from antitumoral therapy, but it is not known whether or not the tumor is also protected in vivo. The aim of the present work was to determine whether GH administration modifies the response by a colonic adenocarcinoma to radiation in vitro and in vivo. BDIX rats were implanted with a colonic adenocarcinoma and two weeks later GH treatment was started. Animals were then irradiated, and four days later samples from the intestines and tumor were taken for analysis. In vitro assays were performed in parallel to confirm the effects observed in vivo. GH reduced radiation-induced intestinal injury by improving proliferation and reducing apoptosis and p53 expression. However, tumor proliferation was reduced by GH while apoptosis and p53 expression remained unchanged. A similar response was observed in vitro. Thus, GH administration before radiotherapy protects the intestines but not the implanted adenocarcinoma in the rat.

Effect of four enteral foods on the small bowel of undernourished rats after midgut resection.

OBJECTIVE To describe the effects of new enteral foods on the adaptation of the gut mucosa after massive intestinal resection in rats. DESIGN Laboratory experiment. SETTING Teaching hospital, Spain. SUBJECTS 91 male Wistar rats, 69 of which were studied (5 were excluded and 17 died). INTERVENTIONS Previously undernourished rats were subjected to either massive bowel resection (n = 30) or laparotomy (n = 26) and fed four enteral hypocaloric diets for 7 days: Alitraq (n = 7 in each group), Impact (n = 8 and 7), Enrich (n = 8 and 6), and Elemental (n = 7 and 6). The remainder were not operated on and fed chow (n = 7) or a diet containing no protein (n = 6). Two diets were high in protein (Alitraq and Impact) and two contained normal amounts (Enrich and Elemental). MAIN OUTCOME MEASURES Bowel mucosal thickness and proliferation; disaccharidase activity; intestinal weight and length; body weight; and plasma somatostatin, IGF-1, and peptide YY concentrations. RESULTS Enriched diets provided a higher body and intestinal weight, and increased length of jejunal and ileal villous size. Peptide concentrations were modified by resection but not by the diet given. Concentrations of somatostatin and insulin-like growth factor were reduced in all groups with the exception of somatostatin in the two diets high in protein in the sham-operated rats. CONCLUSIONS Enriched diets all improve the intestinal adaptive response to massive bowel resection in rats, offering advantages over diets with normal amounts of protein.

Somatostatin blockade improves the proliferative response but not intestinal morphological growth after small bowel resection in rats.

OBJECTIVE To find out whether or not blockade of somatostatin improves intestinal adaptation after small bowel resection. DESIGN Laboratory experiment. SETTING Teaching hospital, Spain. SUBJECTS Eighty adult Wistar rats. INTERVENTIONS Animals underwent intestinal resection or sham operation (n = 40 each) and were treated with a somatostatin antagonist either intermittently or continuously in three different doses (n = 8 each). MAIN OUTCOME MEASURES Bowel mucosal thickness, proliferation and concentrations of cAMP, somatostatin, insulin-like growth factor 1. RESULTS Intestinal resection induced a proliferative and morphometric increase of the mucosa; however, the antagonist increased proliferation only in those animals given the highest dose. Intermittent doses induced a proliferative effect that was stronger than that in the three continuous groups. There was no relationship between trophic stimulus and insulin-like growth factor 1 or cAMP, but somatostatin concentrations increased after the intermittent course. CONCLUSIONS Somatostatin receptor blockade with an antagonist does not cause in normal rats an intestinal morphological adaptation process or increase it after resection; however, it did promote a proliferative stimulus in the crypts.

Growth Hormone Protects the Intestine Preserving Radiotherapy Efficacy on Tumors: A Short-Term Study

The efficacy of radiotherapy on tumors is hampered by its devastating adverse effects on healthy tissue, particularly that of the gastrointestinal tract. These effects cause acute symptoms that are so disruptive to patients that they can lead to interruption of the radiotherapy program. These adverse effects could limit the intensity of radiation received by the patient, resulting in a sublethal dose to the tumor, thus increasing the risk of tumor resistance. The lack of an effective treatment to protect the bowel during radiation therapy to allow higher radiation doses that are lethal to the tumor has become a barrier to implementing effective therapy. In this study, we present a comparative analysis of both intestinal and tumor tissue in regard to the efficacy and the preventive impact of a short-term growth hormone (GH) treatment in tumor-bearing rats as a protective agent during radiotherapy. Our data show that the exogenous administration of GH improved intestinal recovery after radiation treatment while preserving the therapeutic effect against the tumor. GH significantly increased proliferation in the irradiated intestine but not in the irradiated tumors, as assessed by Positron Emission Tomography and the proliferative markers Ki67, cyclin D3, and Proliferating Cell Nuclear Antigen. This proliferative effect was consistent with a significant increase in irradiated intestinal villi and crypt length. Furthermore, GH significantly decreased caspase-3 activity in the intestine, whereas GH did not produce this effect in the irradiated tumors. In conclusion, short-term GH treatment protects the bowel, inducing proliferation while reducing apoptosis in healthy intestinal tissue and preserving radiotherapy efficacy on tumors.

Growth hormone increases neural cell adhesion polysialylation state in the dentate gyrus of γ‐irradiated rats

Prenatal irradiation has severe consequences in the central nervous system (CNS), ranging from microcephaly and subcortical heteropia to cognitive dysfunction in rodents (Schull and Otake, 1991; Schull et al., 1990). Radiation exposure induces cerebral cortex malformation, mental retardation, and attention deficit-hyperactivity disorders in humans (Mizumatsu et al., 2003; Monje, 2008; Schull and Otake, 1991; Schull et al., 1990); in adult g-irradiated rats, it causes memory impairment (Sienkiewicz et al., 1994). Neural cell adhesion molecule (NCAM) is the major carrier of 2,8-linked sialic acid residues (PSA), which are only present in regions of synaptic plasticity and permanent neurogenesis in the adult rat brain. NCAM is involved in synaptogenesis, neuroprotection, axonal sprouting and, memory formation (Cremer et al., 2000; Merino et al., 2000). Polysialic acid (PSA) is a posttranslational modification of NCAM that promotes plasticity and allows structural remodeling in the brain (Kiss and Rougon, 1997). Different products have been used against the detrimental effects of gamma radiation in rodents, including growth hormone (GH) (Gómez de Segura et al., 1998; Madrid et al., 2002). Several studies have identified GH-receptors in the hippocampus and the prefrontal cortex (Lobie et al., 1993; Zhai et al., 1994). The pleiotropic actions of GH in the CNS range from neuroprotection, neurogenesis (Scheepens et al., 2001), axonal elongation, and dendritic arborization, to neuronal migration, and it can reduce cognitive impairment (Aberg et al., 2000; Muresanu et al., 2006; Sienkiewicz et al., 2000). Because these brain processes are regulated by PSA-NCAM and hormones, including GH, we wanted to ascertain whether PSA-NCAM might be a target for GH effects in the dentate gyrus of g-irradiated rats. Few studies have investigated the relationship between cell adhesion molecules and the effect of GH in the hippocampus of g-irradiated rats (Hienz et al., 2008). The possibility that GH induces remodelatory effects and/or lessens cell death in the hippocampus of g-irradiated rats through a regulation of PSANCAM protein levels has not been investigated. To answer these questions, we evaluated PSA-NCAM levels by immunofluorescence and CXCR4 by immunoblot in the hippocampus of g-irradiated either treated or not treated with GH. We also analyzed whether GH exerts antioxidant effects on SOD-2-Mitochondrial Superoxide Dismutase 2-dependent levels as well as whether GH might regulate CXCR4 protein levels in the hippocampus of g-irradiated rats.

Growth hormone upregulates intestinal trefoil factor expression in the ileum of rats after γ-radiation

Growth hormone (GH) and intestinal trefoil factor (ITF) have been involved in intestinal protection and repair. This study investigates the effects of GH administration on ITF expression and histological changes associated with tissue injury in an intestinal rat model of radiation. Adult male rats were divided into four groups: control, GH, radiation and radiation + GH (GHyRAD). Ileum samples were obtained at 2 or 72 h after radiation and processed to determine ITF levels (mRNA and protein) by quantitative polymerase chain reaction, Western blot and immunohistochemistry. In addition, goblet ITF-positive cells were identified by immunohistochemistry at 72 h. Our results showed an upregulation of mRNA and protein production of ITF in ileum samples after GH and radiation + GH compared with control and irradiated samples. Irradiation alone affected ITF protein expression. However, irradiation after GH pretreatment produced the highest ITF mRNA and protein levels at both the tested time points. ITF-producing goblet cells were identified in intestinal villi (apical location). GH treatment increased the number of ITF-producing goblet cells, and radiation after GH treatment displayed further increase in the number of ITF-positive goblet cells. GH upregulates ITF in normal intestinal tissue. This upregulation is higher when radiation is given after GH treatment. Nevertheless, the mechanism by which GH regulates ITF expression remains unclear and is still under investigation. These results could open up new avenues in the therapeutic reparative and protective effects of GH during radiotherapy and chemotherapy.