Relationship between growth hormone (GH) pulses in the peripheral circulation and GH-releasing hormone and somatostatin profiles in the cerebrospinal fluid of goats

Growth hormone (GH) is secreted in a pulsatile manner, but the underlying mechanisms of GH pulse generation remain to be resolved. In the present study, we investigated the relationship between GH pulses in the peripheral circulation and GH-releasing hormone (GHRH) and somatostatin (SRIF) profiles in the cerebrospinal fluid (CSF) of male goats. The effects of an intracerebroventricular (icv) injection of neuropeptide Y (NPY), galanin and ghrelin were also analyzed. Blood and CSF samples were collected every 15 min for 8 hr from the jugular vein and third ventricle, respectively. GH pulsatility in the goat was found to consist of distinct large pulses of 5 hr periodicity and small pulses of 1 hr periodicity. GHRH and SRIF in the CSF fluctuated in a pulsatile manner with 1 hr periodicity, and most of the descending phase of SRIF pulses were associated with the initiation of GH pulses. Icv injections of NPY, galanin and ghrelin stimulated GHRH release without affecting SRIF release. In addition, NPY suppressed, and galanin and ghrelin induced large GH pulses, although ghrelin was much more effective than galanin. These results suggest that an hourly fall in SRIF is involved in generating intrinsic circhoral rhythm of GH pulsatility. The mechanisms underlying the generation of large GH pulses of 5 hr periodicity remain unknown, while direct action of NPY and/or ghrelin on the pituitary might be involved.     

Correlation between spontaneous feeding behavior and neuropeptide Y profile in the third ventricular cerebrospinal fluid of goats

Feeding behavior is regulated by neural signals in the hypothalamus, but secretory activities of these signals in vivo and their relationship with spontaneous feeding remain to be solved. In the present study, we investigated the correlation between neuropeptide Y (NPY) and somatostatin (SRIF) profiles in cerebrospinal fluid (CSF) and spontaneous feeding behavior in goats. CSF samples were collected every 15 min for 8 h from the third ventricle and feeding behavior was observed throughout the experimental period. The spontaneous feeding behavior, the mean duration of which was 58 min, occurred with an interval of 146 min. NPY in the CSF fluctuated in an episodic fashion with a 145 min interval. Each NPY episode was followed by spontaneous feeding with a time lag of 24 min. SRIF levels in CSF changed more frequently in a pulsatile manner and were related to neither NPY profiles nor feeding behavior. These results suggest that NPY, but not SRIF, is a physiological signal to drive feeding in goats.     

Effects of photoperiod on the secretion of growth hormone in female goats

The aim of the present study was to clarify the effect of photoperiod on the secretion of growth hormone (GH) in goats. Adult female goats were kept at 20°C with an 8‐h or 16‐h photoperiod, and secretory patterns of GH for 4 h (12.00 to 16.00 hours) were compared. In addition, the goats were kept under a 16‐h photoperiod and orally administered saline (controls) or melatonin, and the effects of melatonin on the secretion of GH were examined. GH was secreted in a pulsatile manner. There were no significant differences in pulse frequency between the 8‐ and 16‐h photoperiods; however, GH pulse amplitude tended to be greater in the group with the 16‐h photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the 16‐h photoperiod (P < 0.05). The GH‐releasing response to GH‐releasing hormone (GHRH) was also significantly greater for the 16‐h photoperiod (P < 0.05). There were no significant differences in GH pulse frequency between the saline‐ and melatonin‐treated groups. However, GH pulse amplitude and mean GH concentrations were significantly greater in the saline‐treated group (P < 0.05). The present results show that a long photoperiod enhances the secretion of GH, and melatonin modifies GH secretion in female goats.     

Effects of photoperiod on secretory patterns of growth hormone in adult male goats

The aim of the present study was to clarify the effect of photoperiod on secretory patterns of growth hormone (GH) in male goats. Adult male goats were kept at 20°C with an 8‐h or 16‐h light photoperiod, and secretory patterns of GH secretion were compared. In addition, plasma profiles of prolactin (PRL), insulin‐like growth factor‐I (IGF‐I) and testosterone (T) were also examined to characterize GH secretion. GH was secreted in a pulsatile manner. There was no significant difference in pulse frequency between the 8‐h and 16‐h photoperiods. However, GH pulse amplitude tended to be greater in the group with the 16‐h photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the 16‐h photoperiod (P < 0.05). The GH‐releasing response to GH releasing hormone was greater in the 16‐h than 8‐h photoperiod (P < 0.05). Plasma PRL and IGF‐I levels were higher in the 16‐h than 8‐h photoperiod (P < 0.05). In contrast, plasma T levels were lower in the 16‐h photoperiod (P < 0.05). These results show that a long light photoperiod enhances the secretion of GH as well as PRL and IGF‐I, but reduces plasma T concentrations in male goats.     

Effects of photoperiod on the secretion of growth hormone and prolactin during nighttime in female goats

The aim of the present study was to clarify the effect of photoperiod on nighttime secretion of growth hormone (GH) in goats. Adult female goats were kept at 20°C with an 8 h or 16 h dark photoperiod, and secretory patterns of GH for 8 h in the dark period were examined with the profile of prolactin (PRL) secretion. GH was secreted in a pulsatile manner in the dark period. There were no significant differences in pulse frequency between the 8‐ and 16‐h dark photoperiods; however, pulse amplitude tended to be greater in the group with the 16‐h dark photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the same photoperiod (P < 0.05). PRL secretion increased quickly after lights off under both photoperiods. The PRL‐releasing responses were weaker in the 8‐h than 16‐h dark photoperiod. The secretory response to photoperiod was more obvious for PRL than GH. The present results show that a long dark photoperiod enhances the nighttime secretion of GH in female goats, although the response is not as obvious as that for PRL.     

Biochemical alterations in serum and cerebrospinal fluid in experimental acidosis in goats

Experimental acidosis was induced in six goats aged between one and two years by administration of whole wheat grain at 100 g kg-1 bodyweight given intraruminally. Blood and cerebrospinal fluid (CSF) samples were collected from these goats before administration of wheat grain (0 hour) and thereafter at 12, 24, 48, 72, 96 and 120 hour intervals. These were analysed for serum enzyme activities and physicochemical characters of CSF. Significantly (P less than 0.05) higher activities of amylase (at 12 hours), lactate dehydrogenase (12 to 48 hours), creatine phosphokinase (12 to 48 hours), aspartate aminotransferase (12 to 24 hours), and gamma-glutamyl transferase (12 to 96 hours) were found in serum samples of acidotic goats. Changes in CSF included decrease of pH and chloride content and higher glucose values. No difference was seen in the physical character of CSF collected at different time intervals from acidotic goats.     

饲喂半胱胺后辽宁绒山羊血液、瘤胃和盲肠内巯基含量的变化

本试验选用4头6月龄、平均体重为16kg左右、安装永久性瘤胃瘘管和盲肠瘘管的辽宁绒山羊,平均分为半胱胺组和对照组,观察辽宁绒山羊血液、瘤胃和盲肠内巯基含量的变化。结果表明:饲喂半胱胺后,瘤胃与盲肠中巯基含量总的变化趋势相同,均于采食后1～2h达到最高值,而后下降。与对照组相比,半胱胺组盲肠液中巯基含量比对照组提高9.92%(P0.05),瘤胃液中巯基含量显著提高36.56%(P0.05),血液中巯基含量显著提高20.75%(P0.05)。本研究结果提示,给辽宁绒山羊饲喂半胱胺后,巯基吸收部位主要位于瘤胃与盲肠之间的前段消化道。     

Luteinizing hormone and growth hormone secretion in ewes infused intracerebroventricularly with neuropeptide Y

Neuropeptide Y (NPY) provides an important hypothalamic link between nutritional status and neuroendocrine mechanisms regulating growth and reproduction. The objective of the following series of experiments was to determine the effects of single or continuous administration of NPY on secretion of luteinizing hormone (LH) and (or) growth hormone (GH). In experiment 1, four ovariectomized (OVX) ewes and four OVX + estrogen-treated ewes each received, in a 4 x 4 Latin Square arrangement of treatments, a single injection of 0, 0.5, 5, or 50 microg NPY via an intracerebroventricular (i.c.v.) cannulae to determine the effects on secretion of GH. NPY significantly elevated serum GH at the 50 microg dose regardless of estrogen exposure (P = 0.003). In experiment 2, eight OVX ewes were infused i.c.v. with NPY or saline (n = 4/trmt) continuously for 20 h in a linearly increasing dose, ending at 50 microg/h NPY. Blood samples were collected via jugular cannulae every 10 min during hour -4-0 (interval 1, pre-treatment), hour 6-10 (interval 2) and hour 16-20 (interval 3) relative to the initiation of infusion (0 h). Mean LH and LH pulse frequency were lower in NPY- versus saline-infused ewes during intervals 2 and 3 (P < 0.01), but NPY had no discernable effect on serum GH (P > 0.10). In experiment 3, four OVX ewes were continuously infused with NPY as in experiment 2, except that the maximum 50 microg/h dose was achieved after only 10 h of infusion. Blood samples were collected every 10 min, beginning 4 h before and continuing until 4h after the NPY infusion. Mean serum LH changed significantly over time (P = 0.0001), decreasing below pre-treatment levels by hour 3 of NPY infusion (P < 0.01), and returning to pre-treatment concentrations following the end of infusion (P > 0.15). Serum GH also changed significantly over time (P < 0.001). Mean GH levels tended to be greater than pre-treatment levels by hour 2 of infusion (P < 0.08), but thereafter returned to basal levels. Serum GH also increased following the end of NPY infusion (P < 0.03). From these data we conclude that NPY exerts a persistent inhibitory effect on secretion of LH, and may stimulate the secretion of GH during the initiation and cessation of infusion of NPY. These observations support a role for NPY in mediating the effects of undernutrition on both LH and GH, and also provide evidence for potential mechanisms by which leptin, acting through NPY, may stimulate the secretion of GH.     

Acid-base indices in ovine blood and cerebrospinal fluid]

By means of the Astrup apparatus (Blood Microsystem BMS 2) acid-base indices in blood and cerebro-spinal fluid of clinically healthy Merino sheep at the age of one year (15 head) and of two or three years (41 head) were determined. Blood collected anaerobically from v. jugularis and liquor collected by means of the suboccipital punction in heparinized syringes and/or caplaris and liquor collected by means of the suboccipital punction in heparinized syringes and/or capillaries were examined immediately after the collection. Following indices were obtained and re-counted according to nomograms: actual pH, partial CO2 pressure--pCO2 base excess--BE, base buffer--BB, standard bicarbonate--SB, actual bicarbonate--AB, total CO2--tCO2 (Tables I, II). Indices of pH, pCO2, BE and BB indicated statistically significant differences in values when comparing liquor with venous blood (in younger ewes). As the values of the sheep cerebro-spinal fluid indices examined are not to be found in literature, the above stated values can be recommended to be used as basic values for a given age group.     

捻转血矛线虫谷胱甘肽过氧化物酶体外对山羊外周血单核细胞功能的影响

本文探讨了捻转血矛线虫的谷胱甘肽过氧化物酶(HC29)体外对山羊外周血单核细胞(PBMCs)功能的影响。颈静脉采取无捻转血矛线虫感染的山羊血液,分离单核细胞后加入终浓度为5μg/mL的HC29重组蛋白进行体外培养,通过免疫荧光抗体技术观察重组蛋白与单核细胞的结合情况;HC29刺激山羊外周血单核细胞,用qPCR技术测定各试验组单核细胞中IL-2、IL-4、IL-10、IL-17、IFN-γ和TGF-βmRNA的转录水平;重组蛋白刺激单核细胞,采用CCK-8法测定细胞的增值情况;将重组蛋白与巨噬细胞共培养,测定巨噬细胞吞噬和分泌NO的情况。结果表明,重组HC29能够与外周血单核细胞结合并刺激细胞因子IL-10和IFN-γ的表达水平显著提高(P<0.01),能够引起单核细胞增值(P<0.01),巨噬细胞吞噬作用增强(P<0.01)和NO分泌增加(P<0.01)。结果表明HC29是捻转血矛线虫的一个重要抗原,主要诱导Th1类免疫反应。     

The immunophenotype of blood and cerebrospinal fluid mononuclear cells in dogs

Inflammatory neurologic diseases are common in dogs, but establishing a definitive diagnosis often is difficult. Nucleated cell number and type in cerebrospinal fluid (CSF) rarely are suggestive of an etiologic agent. We speculated that CSF leukocyte immunophenotyping would be a useful adjunct in the investigation of canine inflammatory neurologic diseases by yielding more specific etiologic information. The goals of this study were to establish the feasibility of flow cytometric evaluation of individual canine CSF samples and to identify the cell distribution in healthy dogs. The mononuclear cell populations of paired blood and CSF samples from 23 healthy dogs were characterized by labeling of cells with antibodies against CD4, CD8alpha, CD21, and CD14 molecules and by flow cytometric analysis of their expression. The mean proportion of CD4+ and CD21+ cells was significantly higher in blood than in the CSF (P < .002 and P < .001, respectively). In contrast, the mean proportion of CD14+ and CD8a+ cells was not significantly different between blood and CSF (P = .5 and p = .9, respectively). These findings demonstrate differences in the distribution and function of mononuclear cells in the circulating venous and subarachnoid compartments in the dog.     

Investigations on the treatment of cerebrospinal nematode infections in goats

In 17 goats the therapeutical outcome of cerebrospinal nematodiasis, a parasitic infection in the central nervous system with the nematode Elaphostrongylus cervi, is described. The diagnosis was made on the basis of physical findings and cerebrospinal fluid eosinophilia. The therapy was based on the administration of a non-steroidal antiinflammatory drug (flunixin meglumine) and two anthelmintics (fenbendazol, ivermectin) for five days. The response to therapy was documented immediately and 30 days after therapy and by owners report up to 30 months. Eleven goats (64.7%) showed an improvement of the neurological signs directly after therapy. Three had a complete recovery. Signs of a light and middle ataxie were still present in 6 and 2 goats, respectively. Six recumbent goats (35.3%) had to be euthanasied because of a non-therapeutical response. This study has shown a clinical impression of successful use of flunixin meglumine, fenbendazole and ivermectin in goats with light to middle neurological signs. The goats could accommodate the remaining ataxia without showing a reduced production. Goats with high neurological deficits could not be successful treated based on the high degree of the neurological damage.     

蛋白质源对山羊瘤胃微生物蛋白AA组成的影响

以4只瘘管山羊作为试验动物,研究羽毛粉(A)、玉米蛋白粉(B)、豆粕(C)和鱼粉(D)等蛋白质源配合的混合日粮对瘤胃微生物蛋白AA组成模式的影响规律。采用4×4拉丁方设计进行试验。结果表明:部分种类AA的含量在原虫和细菌区系间和同一区系内不同蛋白质处理间差异显著。原虫的Val比例高于细菌的,而细菌的Lys则高于原虫。细菌的Arg,原虫的Met、Leu和His在蛋白质处理间差异显著。综上可见,瘤胃微生物AA组成是因蛋白质来源而变化的。     

日粮营养和半胱胺制剂对山羊手术前后淋巴细胞转化的影响

研究了日粮营养和口服半胱胺制剂对山羊手术前后淋巴细胞转化能力的影响。结果显示 ,正常生理状况下 ,增加日粮营养可显著提高山羊淋巴细胞转化能力 (P <0 0 5)。半胱胺制剂可改善手术创伤导致的免疫抑制 ,显著阻止严重手术创伤后淋巴细胞的刺激指数的下降 (P <0 0 5)。