Regulation of growth hormone receptor and binding protein expression in domestic species

The authors report two cases of postoperative lagophthalmos immediately following ab externo dacrycystorhinostomy (DCR). Two female patients, aged 67 and 62 years, underwent under general analgesia for chronic dacryocystitis with mucocele. An inferior surgical approach, sparing the inner canthal ligament was chosen in both cases. Lagophthalmos was observed on the operated side on the first postoperative day. Normal lid occlusion was present on the contralateral side. Impairement of palpebral occlusion was predominant in the nasal portion of the lid fissure. Upon voluntary and reflex blinking, a reduction in the downward movement of the superior lid was observed. This reduction was not as apparent when the patients were asked to produce a forced blink. Lagophthalmos disappeared progressively over 3 postoperative months in both cases. Neither epiphora nor any corneal complications were observed. Lagophthalmos following DCR via an inferior approach is a previously unreported complication and may be related to the disinsertion of the nasal portion of the orbicularis muscle and periosteum at the time of periosteal cleavage. Recovery of normal lid function may be due to reattachment of the periosteum.     

Growth hormone-insulin-like growth factor-I axis in adult insulin-dependent diabetic patients: evidence for central hypersensitivity to growth hormone-releasing hormone and peripheral resistance to growth hormone

The aim of this study was to assess the GH-IGFI axis, GH receptor availability, as reflected by the levels of GH-BP, and the amount of GH-dependent IGFBP-3 in adult IDDM patients with different degrees of metabolic control. Thus, 10 adult well-controlled IDDMs (HbA1 7.8 +/- 0.4%), 10 adult non-ketotic poorly controlled IDDMs (HbA1 13.3 +/- 7%) and 14 sex- and age-matched healthy controls were subjected to two intravenous GH-RH stimulation tests with 0.1 and 1.0 microg/kg body weight respectively, and a plasma IGF-1 generation test induced by the administration of hGH. Poorly controlled IDDM patients exhibited an exaggerated GH response to 1.0 microg/kg of GH-RH when compared to healthy control subjects. Low fasting plasma IGF-1 levels and a blunted IGF-1 response to exogenously administered hGH were also found in poorly controlled IDDMs when compared to the healthy control group. GH-BP levels were significantly lower in IDDMs than in normal controls, and correlated positively with the IGF-1 generation capacity after hGH. Serum IGFBP-3 levels measured by RIA were similar in IDDM and control groups. Good glycemic control for 5.7 +/- 0.9 months did not correct the above mentioned abnormalities of the GH-IGF-1 axis. Our findings suggest that IDDM is associated with a diminished availability of GH receptors and synthesis of IGF-1. GH might then increase as a compensatory mechanism, further down-regulating liver GH receptors, and thus perpetuating the initial abnormality.     

Passive cutaneous anaphylaxis in the domestic fowl

Histochemical demonstration of beta-glucuronidase was carried out in the normal and regenerating tail of the house lizard, Hemidactylus flaviviridis. Greater enzyme activity was particularly discernible in the stratum germinativum of the skin of the normal and fully regenerated tail. During regeneration most of the cellular elements of the blastema and the differentiating regenerate exhibited enzyme activity. Distribution of the enzyme beta-glucuronidase is correlated with the high degree of cellular proliferation. The role of the enzyme in the catabolism of mucopolysaccharides is also implicated during the wound-healing phase. In the full-grown regenerate the intensity and distribution of the enzyme activity were found to be the same as those observed in the normal tail.     

Female mate choice and male behaviour in domestic fowl

An F2 intercross derived from C57BL/6 and DBA/2 progenitor inbred strains was used to test for replication of quantitative trait loci (QTLs) for alcohol preference nominated by a previous study using BXD recombinant inbred (RI) strains (Rodriguez et al., Alcohol. Clin. Exp. Res. 19:367-379, 1995). Fourteen provisional QTLs were nominated in the original RI study with a p < 0.05 criterion. In the present study, a genome scan (101 microsatellite markers) was conducted on an F2 population (n = 218). Three significant QTLs were detected on chromosomes 1, 4, and 9, and three suggestive QTLs were detected on chromosomes 2, 3, and 10. Of these six QTLs, four were consistent with the previous RI nominations. The replication rate of 28.6% (4 of 14) is in agreement with the results of simulation studies performed by Belknap et al. (Behav. Genet. 26:149-160, 1996) and supports the methodological argument for a multistage research design for nominating and replicating QTLs.     

Ontogeny of insulin-like growth factors (IGF), IGF binding proteins, IGF receptors, and growth hormone receptor mRNA levels in porcine pancreas

We examined the ontogeny of mRNA levels of IGF-I and -II, IGF type 1 (IGFI-R) and type II receptors (IGFII-R), IGF binding protein-1 and -3 (IGFBP-1 and -3), GH receptor (GHR), and tissue concentrations of IGF and IGFBP in the pancreas of pigs. Tissues were collected from fetuses at 90 and 110 d of gestation and from pigs at 1, 21, 90 and 180 d of age. Northern blots were performed using total RNA hybridized with 32P-labeled cDNA probes (human IGF-I and human IGFI-R) and cRNA probes (rat IGF-II, human IGFII-R, human IGFBP-1, pig IGFBP-3, and pig GHR). There were two accelerated growth stages of the pancreas: the first one at 90 d of fetal life, which is characterized by cell hyperplasia (high ratio of DNA to body weight), and the second one at postnatal 90 d, which is attributed to cell hypertrophy (high ratios of pancreatic weight, RNA, and protein to DNA). The level of IGF-II mRNA and its tissue concentration were predominant during fetal life and low thereafter. The IGF-I mRNA level was high during fetal and early postnatal life and decreased thereafter. Messenger RNA levels of IGFI-R, IGFBP-3, and GHR and concentrations of IGFBP-1 and -2 were abundant during fetal and early postnatal life. In conclusion, IGF may be involved in various physiological periods of pancreatic development in pigs.     

Angiotensin-induced dipsogenesis in domestic fowl ( Gallus gallus ).

Both systemic (100, 200, and 400 mug, im) and intracranial (75, 150, and 300 ng) injections of Val-sup-5-angiotensin II-amide produced copious and dose-related drinking in 6 male White Leghorn chickens in normal water balance. Angiotensin-induced drinking has been reported in several mammalian species and in Barbary doves and white-crowned sparrows. The results of the 2 experiments reported here extend the species generality of angiotensin-induced thirst and are evaluated in light of current biochemical and pharmacological analyses of the renin-angiotensin system in chickens. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cocaine-conditioned place preference in young precocial domestic fowl.

Experiment 1 established conditioned place preference (CPP) control procedures for young precocial domestic fowl (test day age?=?13–25 days). Chicks displayed a preference (greater choice time) for white stimulus cards on first exposure to white versus red cards and equivalent preference for these stimulus cards after 6 exposures. Chicks in Experiment 2 displayed a cocaine CPP at each dose (0.5, 1.0, and 2.0 mg/kg intraperitoneally) after 6 cocaine-red card and 6 saline-white card pairings. This CPP decreased and was no longer significant over 2 additional nonreinforced test days. Experiment 3 results replicated the cocaine CPP (2.0 mg/kg) and demonstrated that the CPP did not develop when cocaine was administered several hours after card exposure. To our knowledge, these results are the first to demonstrate drug CPP in a nonmammalian model and support the notion that drug reinforcement processes are highly conserved. This precocial avian model may prove a useful addition to existing altricial models for the study of determinants of human drug use and abuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute central effects of 5,6-dihydroxytryptamine in fowl

In adult hens (Gallus domesticus) infusion into the IIIrd cerebral ventricle of 5,6-DHT (50, 75 and 100 mug) produced, after 5-10 min behavioural and electrocortical sedation and sleep lasting about 6-8 hr,and a monophasic or biphasic increase in body temperature for about 8 hr, Two and a half hr after 5,6-DHT administration, the histochemical picture showed a sustained decrease in yellow and green fluorescence in areas adjacent to the IIIrd ventricle, in the anterior hypothalamus and in the preoptic area, whereas no significant changes were detected in fluorescence of the tegmental cell-bodies. The present experiments suggest that behavioural and electrocortical effects evoked by 5,6-DHT seem to be due to a synergistic action of 5-HT and catecholamines displaced and released by this compound, whereas hyperthermic effects seem to be due to a more sustained release of 5-HT and/or to a direct action on 5-HT receptors and/or inhibition of 5-HT reuptake.     

Regulation of rat pituitary gonadotropin-releasing hormone receptor mRNA levels in vivo and in vitro

The recent isolation of cDNAs encoding the rat pituitary gonadotropin-releasing hormone receptor (GnRHR) allows studies of the regulation of the synthesis of the GnRHR and its relationship to reproductive function. Analyses of the regulation of GnRHR mRNA levels in the rat pituitary in vivo revealed a progressive increase in levels to 2.0 +/- 0.2-fold after ovariectomy (OVX) and 5.2 +/- 1.3-fold after castration (CAST) (21 days post-operative), compared to intact adult female and male controls, respectively. Replacement therapy with 17 beta-estradiol benzoate in 21-day post-OVX female rats resulted in a marked decrease in GnRHR mRNA levels by 7 days, compared to controls. In contrast, therapy with testosterone propionate in 21-day post-CAST male rats resulted in only a modest decrease in GnRHR mRNA levels. Thus, manipulation of the reproductive endocrine system in vivo results in alterations in GnRHR synthesis at the pretranslational level, which parallel known changes in cell surface gonadotropin-releasing hormone (GnRH) binding activities. The treatment of superfused primary monolayer cultures of rat pituitary cells with hourly pulses of GnRH (10 nM, 6 min/h) resulted in a marked increase in GnRHR mRNA levels (12.8 +/- 4.3-fold compared to untreated cells). In contrast, treatment of cultured cells with continuous GnRH caused no change in GnRHR mRNA levels. These in vitro data show homologous regulation of GnRHR gene expression by GnRH, and suggest that the changes in GnRHR gene expression observed in vivo may be attributable at least in part to changes in the pattern of hypothalamic GnRH secretion.     

Mycoplasmas in wild turkeys living in association with domestic fowl

One hundred and nineteen Merriam's wild turkeys (Meleagris gallopavo merriami) and 31 domestic chickens coexisting on a ranch in west-central Colorado (USA) were surveyed for mycoplasmosis by serologic and cultural methods. Although no clinical signs were apparent in any wild turkeys tested, 51 (43%) had positive rapid plate agglutination (RPA) reactions for M. gallisepticum (MG) and/or M. synoviae (MS); 37% of 56 adults and 48% of 63 subadults were classified as positive reactors to MG and/or MS. No turkeys tested in 1992 (n = 61) and 17 (29%) of 58 turkeys tested in 1993 were RPA-positive for M. meleagridis (MM). Hemagglutination inhibition (HI) test results were negative for MG, MS and MM as were most enzyme-linked immunosorbent assay (ELISA) test reactions (MG = 99%, MS = 93%, MM = 87%). Immunoblotting showed mild to moderate reactivity to MG proteins in 49% of 41 samples tested. Most chickens were strongly positive for MS by RPA (81%), HI (58%) and ELISA (87%); 48% also were positive for MG by RPA but all were MG-negative by HI and ELISA. No pathogenic mycoplasmas were isolated from either group of birds. Mycoplasma gallopavonis was commonly identified from the wild turkeys, and M. gallinaceum was isolated from both the chickens and wild turkeys. In a transmission study conducted in 1994, disease-free domestic turkeys failed to seroconvert when co-housed with wild turkeys from this population that were RPA-positive for MG. Collectively, the results of this study were inconclusive regarding the status of pathogenic mycoplasmas within this wild turkey population.     

Distribution of prepro-nociceptin/orphanin FQ mRNA and its receptor mRNA in developing and adult mouse central nervous systems

In previous studies we have shown that the insulin-responding glucose transporter isoform of 3T3-L1 adipocytes, GluT4, is almost completely located on microvilli. Furthermore, insulin caused the integration of these microvilli into the plasma membrane, suggesting that insulin-induced stimulation of glucose uptake may be due to the destruction of the cytoskeletal diffusion barrier formed by the actin filament bundle of the microvillar shaft regions [Lange et al. (1990) FEBS Lett. 261, 459-463; Lange et al. (1990) FEBS Lett. 276, 39-41]. Similar shape changes in microvilli were observed when the transport rates of adipocytes were modulated by glucose feeding or starvation. Here we demonstrate that the action of insulin on the surface morphology of hepatocytes is identical to that on 3T3L1 adipocytes; small and narrow microvilli on the surface of unstimulated hepatocytes were rapidly shortened and dilated on top of large domed surface areas. The aspect and mechanism of this effect are closely related to "membrane ruffling" induced by insulin and other growth factors. Pretreatment of hepatocytes with the PI 3-kinase inhibitor wortmannin (100 nM), which completely prevents transport stimulation by insulin in adipocytes and other cell types, also inhibited insulin-induced shape changes in microvilli on the hepatocyte surface. In contrast, vasopressin-induced microvillar shape changes in hepatocytes [Lange et al. (1997) Exp. Cell Res. 234, 486-497] were insensitive to wortmannin pretreatment. These findings indicate that PI 3-kinase products are necessary for stimulation of submembrane microfilament dynamics and that cytoskeletal reorganization is critically involved in insulin stimulation of transport processes. The mechanism of the insulin-induced cytoskeletal reorganization can be explained on the basis of the recent finding of Lu et al. [Biochemistry 35(1996) 14027-14034] that PI 3-kinase products exhibit much higher affinity for the profilin-actin complex than the primary products, PIP and PIP2. Thus, activated PI 3-kinase may direct a flux of profilin-actin complexes to the membrane locations of activated insulin receptors, where, due to the release of actin monomers after binding of profilactin to PI(3,4)P2 and PI(3,4,5)P3, massive actin polymerization is initiated. As a consequence, PI 3-kinase activation initiates a vectorial reorganization of the cellular actin system to membrane sites neighboring activated insulin receptors, giving rise to local membrane stress as visualized by extensive surface deformations and shortening of microvilli. In addition, extensive high-affinity binding of F-actin-barbed endcapping proteins enhances the cytoplasmic concentration of rapidly polymerizing filament ends. Consequently, the actin monomer concentration is lowered and the (cytoplasmic) pointed ends of the microvillar shaft bundle depolymerize and become shorter. The observations presented strengthen the previously postulated diffusion-barrier concept of glucose- and ion-uptake regulation and provide a mechanistic basis for explaining the action of insulin and other growth factors on transport processes across the plasma membrane.     

Patterns of ovarian growth and development in cattle with a growth hormone receptor deficiency

Nutritionally induced changes in growth hormone (GH) and IGF-I are associated with decreased ovarian function and may partially explain infertility and anestrus in undernourished cattle. The reproductive importance of GH and IGF-I was tested in cattle with a GH receptor deficiency (GHRD) that have reduced blood IGF-I. Blood was collected daily for plasma, and ovaries were examined daily by ultrasonography for 3 wk during an estrous cycle (estrus = d 0) in GHRD (n = 8) and control (n = 8) cattle. On d 18, blood samples were collected every 10 min for 6 h to measure LH. The GHRD cattle had fewer small antral ovarian follicles (2 to 5 mm, P < .01). After estrous cycle d 5, the first-wave dominant follicle stopped growing in GHRD but continued growing in controls (P < .001). Size of the CL was equivalent for GHRD and controls until d 5, after which CL development slowed in GHRD (P < .01). Likewise, plasma progesterone concentrations were less in GHRD (P < .001). During the luteal phase, GHRD cattle failed to develop follicles greater than 10 mm in diameter (endocrine status x day, P < .05). Size and rate of growth of preovulatory follicles, plasma estradiol, plasma FSH, and plasma LH (d 18 bleed) were similar in GHRD and controls. In conclusion, an important role for GH, GH receptor, and IGF-I in ovarian function was supported because GHRD cattle had distinctly different patterns of ovarian development compared with control cattle.     

Prolactin and growth hormone mRNA and protein characterization in SMtTW rat pituitary tumours

During human pregnancy, plasma corticotrophin-releasing hormone (CRH) levels rise from undetectable amounts prior to 20 weeks gestation to reach a peak near term, with an exponential rise during the final 5 weeks of gestation. Within hours of parturition plasma levels fall and rapidly return to undetectable baseline measurements. The appearance of CRH in maternal plasma has been attributed to the placental production and subsequent release into the maternal circulation of this hormone. Previous studies have shown that human placental extracts contain a CRH-like peptide and this has been reinforced by the observation of CRH mRNA in placental tissue. Initial attempts to identify the site of production using immunocytochemistry have led to conflicting results. This study attempts to clarify this situation by using a variety of highly specific anti-CRH antibodies to show the cellular expression of placental CRH. Intense CRH staining was observed in the syncytial trophoblast layer in first trimester and term chorionic villi, whilst the underlying cytotrophoblast appeared to be negative. The fetal membranes also contained CRH immunoreactivity with the cytotrophoblast cells in the chorionic membrane displaying the most intense staining. CRH immunoactivity was also observed in the amnion and in some cells in the decidua. As a model of cellular CRH expression, cytotrophoblast cells from term chorionic membrane were isolated and shown to be positive for CRH.