Age-related changes of the somatotropic axis in cloned Holstein calves

To determine if the development of the somatotropic axis in somatic clones (clones) is similar to that in heifers produced by artificial insemination (controls), serum samples were collected every 30 min for 6 h, once per month, for 7 mo from 4 clones generated from a 13-yr-old cow and from 4 age-matched controls. Average concentrations of growth hormone (GH) were not different between clones and controls, and GH concentrations declined over time in controls. Average concentrations of insulin-like growth factor I (IGF-I) were less in clones than controls, and IGF-I concentrations increased over time in both groups. Concentrations of IGF-binding protein 3 (IGFBP-3) were greater in controls than in clones and did not change over time. Average IGFBP-2 concentrations did not change over time and were not different between clones and controls. Clones and controls were challenged with GH-releasing hormone (GHRH) (3 microg/100 kg body weight) and somatostatin (somatotropin release-inhibiting factor [SRIF]) (1.87 and 5 microg/100 kg body weight) at 14 mo of age. GHRH-induced GH secretion was greater and SRIF inhibition of GHRH-induced GH was less in clones than in controls. We speculate that some of the differences between clones and controls in concentrations of GH, IGF-I, and IGFBP-3 may be related to the genetic merit of the animals. Although there were differences in concentrations of components of the somatotropic axis between these clones and their age-matched controls, the values recorded were all within the range reported for calves of similar ages.     

Measuring social-cognitive functions in children with somatotropic axis dysfunction

Growth hormone (GH) and insulin-like growth factor I (IGF-I) are expressed in specific regions of the central nervous system during early human development. They may consequently influence aspects of cognition, or emotional and behavioural adjustment from childhood to adulthood, in conditions associated with abnormalities of the somatotropic axis. GH receptors are relatively common within hippocampal and perihippocampal regions that are primarily involved in declarative memory for facts and events. They are also located in structures (e.g. the putamen) that are involved in the processing of social perceptions. IGF-I receptors have been discovered in the amygdala and prefrontal cortex, which contribute to the neural circuits known as the 'social brain'. The evaluation of emotional, social and behavioural adjustment among children who have deficiencies in GH or IGF-I functional integrity requires the objective assessment of their social-cognitive competence. We describe a computerized test battery, the Schedules for the Assessment of Social Intelligence (SASI), which has been shown to possess excellent psychometric properties in terms of reliability and validity. The SASI, which can be used by both children and adults, may provide new evidence for deficits and treatment effects of GH/IGF-I on emotional, behavioural and cognitive functions.     

Response of the somatotropic axis to alterations in feed intake of channel catfish (Ictalurus punctatus)

To better understand the effects of reduced feeding frequency on the GH–IGF-I axis, channel catfish (Ictalurus punctatus), were either fed (Fed control, commercial diet fed daily), fed every other day (FEOD, commercial diet fed every other day), or not fed (Unfed, no feed). Pituitary GH mRNA increased whereas hepatic growth hormone receptor (GHR), IGF-I mRNA, and plasma IGF-I decreased in the FEOD and Unfed fish (P < 0.05). In another study, fish were either continually fed (Fed) or fasted and then re-fed (Restricted) to examine the physiological regulation of somatostatin-14 (SS-14) and SS-22 mRNA. Fasting increased (P < 0.05) levels of SS-14 mRNA in the hypothalamus and pancreatic islets (Brockmann bodies) at d 30 while re-feeding decreased SS-14 mRNA to control values in all tissues examined by d 45. Fasting had no effect on levels of SS-22 mRNA in the pancreatic islets whereas SS-22 mRNA was not detected in the stomach or hypothalamus. The results demonstrate that feeding every other day has similar negative impacts on components of the GH–IGF-I axis as fasting. The observed increase in SS-14 mRNA in the hypothalamus and pancreatic islets suggests a role for SS-14 in modulating the GH–IGF-I axis in channel catfish.     

Effects of lactoferrin feeding on growth, feed intake and health of calves

Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.     

Effects of lactoferrin feeding on growth,feed intake and health of calves

Abstract

Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.     

Effect of dexamethasone on the neonatal adrenal medulla

Summary Newborn male rats were injected with a single dose of dexamethasone on the first day of life. Controls received only the diluent. Two to ten days later the experimental and control animals were sacrificed, and the adrenal medullae were processed for electron microscopy and for histochemical demonstration of catecholamines. Rats that received dexamethasone, as compared to controls showed (1) an earlier appearance of the catecholamine reaction, and (2) a pronounced development of the Golgi complex. These results are further indication that glucocorticoid stimulates the maturation of the chromaffin complex. The Golgi apparatus may play some role in this inductive mechanism.Supported by grants from Consejo Nacional de Investigaciones Científicas y Técnicas Argentina, and Comisión Asesora de Promotión a la Investigatión, Universidad National de Cuyo, Argentina. We are grateful to Teresa H. Fogal Sarmiento for her technical collaborationScientist of Consejo Nacional de Investigaciones Cientificas y Técnicas, Argentina     

Insulin-like growth factor-I, GH, insulin and glucagon concentrations in bovine colostrum and in plasma of dairy cows and neonatal calves around parturition

1. The IGF-I concentrations in colostrum on days 1 and 2 after parturition were higher than those in cow and neonate plasma. 2. The modest increase in GH concentrations in cow plasma around parturition would not be enough to stimulate IGF-I release by tissues. 3. The concentrations of insulin, GH and glucagon in colostrum were substantially lower than those in plasma.     

Polymorphism analysis in genes of the somatotropic axis in Nellore cattle selected for growth

The somatotropic axis consists of genes that are involved in muscular development. These genes are potential regions of study to identify possible QTL for economically important traits in beef cattle. The aim of this study was to verify the existence of GH1, POU1F1, and GHR polymorphisms in Nellore cattle to verify the influence of selection in these mutations and to analyse the association between molecular markers and body weight at different ages, yearling hip height, carcass fat thickness and loin eye area. Six hundred forty-five animals from the Centro APTA Bovinos de Corte, were genotyped by PCR–RFLP techniques. The association analyses were performed with general mixed models taking into consideration the effect of one marker, and other model taking into consideration interactions between two molecular markers. Only the molecular markers rs81109601 on GH1 and rs109136815 on GHR were polymorphic; however, they were not found to be under selection. The association of the GHR rs109136815 marker and loin eye area was observed (p < 0.05), as well as the effect of interaction between the markers and the female body weight at 550 days of age (p < 0.04). The interaction effect should be considered in situations where the interactivity between two genes is known.     

Interrelation between the cation-anion correlation of cow's blood and colostrum and acid-base state in newborn calves

The neonatal period of the development is characterized by metabolic and functional reorganization in the organism including the acid-alkaline state, that is the important maintain for the metabolic homeostasis. The disturbances in the cation-anion correlation, the decrease of the base reserve in the cows blood and collostrum influence to the cation-anion balance and to the normalization of the acid-alkaline state in the newborn calves that is the reason of decreasing their adaptive abilities.     

Effects of dexamethasone in rat neonatal model of axotomy-induced motoneuronal cell death.

In this study the effect of dexamethasone on the motoneuronal cell death and the nuclear and somatic morphology changes occurring after peripheral nerve transection in the neonatal rats has been determined. The study was performed on 3 day old Wistar rats. Animals were divided into 3 groups--control, axotomised, and axotomised and dexamethasone-treated. The nerve transection was performed bilaterally. A dose of 0.5 mg/kg/24h dexamethasone, administered i.p., was used. On day 7 after the operation the animals were sacrificed and the motoneurons in segments L4 and L5 in the spinal cord were counted and their morphology was analysed. 25. 88% cell loss was found in the axotomised group (p<0.001 vs. control) versus 43.33% cell loss in the dexamethasone-treated and axotomised animals (p<0.01 vs. control). Dexamethasone significantly decreased the number of the surviving motoneurons (p<0.05 vs. axotomised). The axotomised group showed enlargement of the somatic area and the maximal and minimal diameters of the cell while the dexamethasone-treated and axotomised group showed soma shrinkage and decrease in the minimal cell diameter. Our results propose a possible hazard towards the application of dexamethasone in the treatment of new-borns with concomitant nerve injuries.     

Effects of severity of dystocia on cold tolerance and serum concentrations of glucose and cortisol in neonatal beef calves

Effects of dystocia on rectal temperature and serum cortisol and glucose concentrations, were studied in neonatal calves exposed to 0 degree C. Primiparous dams were observed continuously during parturition and if Stage II (labor) was not completed within 2 h after appearance of the allantochorion, delivery was completed with obstetrical assistance. Parturitions were scored (CDS) for difficulty and obstetric assistance required: CDS 1, no assistance (n = 8); CDS 2, minor manual assistance (n = 7); CDS 3, use of a mechanical calf puller (n = 5); CDS 4, cesarean section (n = 6). A blood sample, rectal temperature, and body weight were obtained within 30 min after birth. Calves were then fed 38 degrees C pooled colostrum, muzzled to prevent suckling, and placed back with their dam in a heated (22 degrees C) barn. At 4 h of age an indwelling jugular catheter was inserted. At 5 h of age calves were placed in a 0 degree C room for 140 min and blood samples and rectal temperatures were obtained every 10 or 20 min. A shivering score (1 = no shivering; 2 = moderate shivering; 3 = intense shivering) was assigned at each sampling time. Rectal temperatures were higher (P < 0.01) in CDS 1, 2 and 4 calves (39.0, 39.3, and 39.0 +/- .02 degrees C, respectively) than in calves with CDS 3 (38.3 +/- 0.02 degrees C) and were affected by duration of cold exposure (time; P < 0.01). Shivering was not affected by CDS but was affected by time (P < 0.01). Glucose concentrations were higher (P < 0.01) in CDS 3 calves (110.1 +/- 1.6 mg/dL) than in CDS 1, 2, or 4 calves (77.2, 86.4, and 89.0 +/- 1.3 mg/dL, respectively) and changed over time (P < 0.01). Cortisol concentrations were higher in CDS 1 calves (80.0 +/- 1.7 ng/mL) than in CDS 2, 3 or 4 calves (62.7, 58.2, and 57.7 +/- 2.0 ng/mL, respectively) and were affected by time (P < 0.01). We conclude that severe dystocia (CDS 3) resulted in lower calf rectal temperature, reduced serum cortisol, and increased serum glucose which could affect the ability of the calf to withstand cold stress. Minor dystocia did not cause and timely cesarean delivery prevented, the physiological aberrations encountered in severe dystocia.     

Effects of induction of parturition in ewes with dexamethasone or oestrogen on concentrations of immunoglobulins in colostrum, and absorption of immunoglobulins by lambs

Immunoglobulins were measured in colostral whey from untreated ewes or ewes treated on days 142-145 of gestation with 15 mg oestradiol benzoate (ODB) or 10, 17.5 or 25 mg dexamethasone m-sulfobenzoate (DEX) to induce parturition. DEX at all levels reduced the concentrations of immunoglobulins in colostrum, but ODB had no effect. In a second experiment, similar treatments of ODB and DEX were applied on day 143 of gestation. Lambs were removed from their dams at birth and fed a standard volume of pooled colostrum taken from untreated ewes. They were injected with an antigen (Brucella abortus) at 12 h and 4 weeks of age. Concentrations of immunoglobulins in blood plasma at 24 h after birth of lambs from DEX-treated ewes were lower than for lambs from untreated ewes or from those treated with ODB. Response to the antigen, monitored to 12 weeks of age, was unaffected by either drug. The impairment of transfer of immunoglobulins from ewe to lamb offers a possible explanation for the higher mortality among older lambs found previously after treatment of ewes with DEX.     

Effect of neonatal dexamethasone exposure on growth and neurological development in the adult rat

Until recently, the synthetic glucocorticoid dexamethasone was commonly used to lessen the morbidity of chronic lung disease in premature infants. This practice diminished as dexamethasone use was linked to an increased incidence of cerebral palsy and short-term neurodevelopmental delay. Of more concern is the fact that we know little regarding dexamethasone effects on long-term neurodevelopment. To study the effects of neonatal dexamethasone exposure on long-term neurodevelopment, we have developed a rat model where newborn pups are exposed to tapering doses of dexamethasone at time points corresponding to the neurodevelopmental age when human infants are traditionally exposed to this drug in the neonatal intensive care unit. Using a within-litter design, pups were assigned to one of three groups on postnatal day 2 (P2): handled controls, saline-injected controls, and animals receiving intramuscular dexamethasone between P3 and P6. Somatic growth was decreased in dexamethasone-treated animals. Dexamethasone-treated animals demonstrated slight delays in indexes of neurodevelopment and physical maturation at P7 and P14, but not P20. In adolescence (P45), there was no difference between groups in an open field test. However, as adult dexamethasone-treated animals were less active in the open field and spent more time in closed arms of the elevated plus maze. The serum corticosterone response to crowding stress in dexamethasone-treated animals was no different from controls, but they demonstrate a delay in return of corticosterone levels to baseline. These differences in behavior and hormonal stress responsiveness suggest that neonatal dexamethasone exposure may permanently alter function of the neuroendocrine stress axis.