Förderung der P-Aufnahme von Bohnenpflanzen durch Kinetin

Summary Water culture experiments with 10-day-old plants ofVicia faba were carried out, concerning the influence of kinetin on the uptake of phosphorus (³²P) by the roots. When kinetin was applied to the leaves, the phosphorus uptake of the roots and the upper parts of the plants was increased. On the other hand, when kinetin was added to the nutrient solution, the phosphorus uptake was decreased.     

Similarity between the effects of suprachiasmatic nuclei lesions and of pinealectomy on gonadotropin release in ovariectomized,sulpiride-treated and melatonin-replaced rats

The aim of this study was to compare the effects of pineal indole treatments on LH and FSH release in pinealectomized and suprachiasmatic lesioned and ovariectomized rats rendered hyperprolactinemic by acute sulpiride treatment. pinealectomy or suprachiasmatic nuclei lesions in female rats both decreased plasma LH and FHS at 10, but not at 20 d after surgery, whereas the daily afternoon administration of melatonin effectively restored levels of both gonadotropins to control values. In ovariectomized rats, pinealectomy or suprachiasmatic nuclei lesions were ineffective in counteracting the high plasma levels of LH and FSH. However, sulpiride treatment in both pinealectomized and suprachiasmatic nuclei lesioned and castrated female rats significantly decreased the levels of LH and FSH, an effect which was counteracted by daily afternoon melatonin administration. Other pineal indoles tested, i.e., 5-hydroxy- and 5-methoxytryptophol, were ineffective in regulating gonadotropin levels. The results suggest that the pineal gland, through its hormone melatonin, can modulate gonadotropin secretion by acting on a dopamine mechanism independent of hypothalamic suprachiasmatic areas.     

Effects of monosodium glutamate on circulating concentrations of luteinizing hormone and growth hormone in young growing domestic fowl (Gallus domesticus)

Summary The administration of monosodium glutamate (MSG) at a dose of 4 g/kg in 5-day-old fowl or 5 daily injections of MSG (total dose 20 g/kg) in 1- to 5-day-old fowl did not affect body growth in either male or female domestic fowl. Neither MSG treatment schedule affected either testis weight or the circulating concentration of luteinizing hormone (LH). A small, but significant decrease in the plasma concentration of growth hormone (GH) was observed in female chicks which had received daily MSG injections.Acknowledgments. Paper of Journal Series, New Jersey State Experiment Station, project No. 18141 and 18443, supported by State and Hatch Act funds and grants from the National Science Foundation (PCM 80227227) and the Upjohn Company.     

The effect of gonadotropic hormones and the fetal hypophysis on testosterone production by the testis of 18 day mouse fetuses in organ culture]

The production of testosterone (measured by radioimmuno-assay) by the 18-day-old mouse fetal testis may be stimulated specifically by ovine LH (1 ng, p less than 0.005) and HCG in organ culture. A stimulation by FSH is observed only with high doses (10 mug, p less than 0.0005). Prolactin and ACTH have no effect. Age-matched fetal pituitaries increase significantly the testosterone production in the culture medium (p less than 0.0005).     

Development of melatonin rhythm in the pineal gland and eyes of chick embryo.

A melatonin rhythm was observed in the pineals of 18-day-old chick embryos incubated under a light-dark regime of 18: 6 h. A low pineal melatonin content was found during the light phase of the day. Concentrations started to increase 2 h after dark onset and reached maximum levels after 4 h of darkness. The amplitude of the pineal melatonin rhythm increased considerably after 2 days and night-time concentrations in 20-day-old embryos were more than 5 times higher than in 18-day-old ones. Significant day/night differences in melatonin production were found both in pineals and eyes. Exposure of eggs to 1 h of light during the dark period decreased the high melatonin concentrations in the eyes but not in the pineals of the 20-day-old chick embryo. The results suggest that in this precocial bird at least part of the circadian system may already operate during embryonic life.     

Development of melatonin rhythm in the pineal gland and eyes of chick embryo

A melatonin rhythm was observed in the pineals of 18-day-old chick embryos incubated under a light-dark regime of 186 h. A low pineal melatonin content was found during the light phase of the day. Concentrations started to increase 2 h after dark onset and reached maximum levels after 4 h of darkness. The amplitude of the pineal melatonin rhythm increased considerably after 2 days and night-time concentrations in 20-day-old embryos were more than 5 times higher than in 18-day-old ones. Significant day/night differences in melatonin production were found both in pineals and eyes. Exposure of eggs to 1 h of light during the dark period decreased the high melatonin concentrations in the eyes but not in the pineals of the 20-day-old chick embryo. The results suggest that in this precocial bird at least part of the circadian system may already operate during embryonic life.     

The effect of heat on rat pineal hydroxyindole-omichron-methyl transferase activity.

Exposure of adult male rats to continuously elevated temperature of 32-34 degrees C caused a significant decrease of HIOMT activity involved in the specific metabolic process of production of melatonin, considered an active pineal hormone. The effect was already evident after 24 h exposure and increased further during the next 48 h. The results obtained substantiate previous data that the pineal gland may be involved in the system regulating adaptation to extreme temperature changes.     

Enhancement of serum FSH levels after pinealectomy

Summary The effect of pinealectomy on the circadian periodicity in serum gonadotropins was investigated in adult male rats. Pinealectomy resulted in an elevation of the serum FSH concentration 7 days after the operation. A 4-fold increase in serum FSH over 24 h with no concommitant increase in serum LH following pinealectomy suggests that the control of FSH secretion could be mediated via the pineal gland.     

Enhancement of serum FSH levels after pinealectomy

The effect of pinealectomy on the circadian periodicity in serum gonadotropins was investigated in adult male rats. Pinealectomy resulted in an elevation of the serum FSH concentration 7 days after the operation. A 4-fold increase in serum FSH over 24 h with no concommitant increase in serum LH following pinealectomy suggests that the control of FSH secretion could be mediated via the pineal gland.     

Effects of a bovine pineal peptidic fraction (E5) on plasma and pituitary levels of LH,FSH and prolactin

Summary Pituitary levels of prolactin were significantly diminished after 5 s.c. injections spaced 12 h apart of 5 g of a partially purified bovine pineal peptide fraction (E₅) in both intact and castrated rats. E₅ treatment did not significantly affect the castration-induced changes in plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH) or pituitary LH but did partially block the pituitary fall in FSH in castrated animals.Supported by NSF grant PCM 8003441 and NIH Center for Reproductive Biology (Bioassay Core) No.P30 HD 10202. Many thanks are due A. Moreno for his excellent technical assistance.     

异丙酚对大鼠内毒素脑损伤STAT3表达的影响

目的 研究异丙酚对大鼠内毒素脑损伤中信号转导子与转录激活子-3( STAT3)表达的影响,探讨异丙酚在脑损伤中的保护作用及其机制.方法 健康清洁级SD大鼠72只,雌雄不限,体重220～ 250 g,随机分为3组(n=24):L组(内毒素组)和LP组(内毒素+异丙酚组)经颈内动脉注射内毒素200 μg建立大鼠内毒素脑损伤模型,C组(对照组)经颈内动脉注射等量生理盐水,LP组颈内动脉注射内毒素后即予异丙酚100 mg/kg剂量腹腔注射.3组分别于6、12、24和48h随机处死6只大鼠,取额叶皮质,检测脑组织含水量,免疫组织化学检测P-STAT3、NF-κB和iNOS表达水平的变化,Western blot法检测大鼠内毒素脑损伤后P-STAT3蛋白表达水平的变化.结果 与C组相比,L组、LP组各时间点脑组织含水量、P-STAT3、NF-κB和iNOS表达增加(P ＜0.05,P＜0.01);与L组比较,LP组各时间点脑含水量、P-STAT3、NF-κB和iNOS表达明显减少(P＜0.05,P＜0.01).结论 异丙酚可减轻大鼠内毒素性脑损伤,机制可能与抑制脑组织磷酸化STAT3、NF-κB和iNOS表达水平上调,进而减轻炎性反应有关.     

Role of phospholipid transfer protein in rabbit lung development

A 36-kDa phospholipid transfer protein (PLT-P_R), which preferentially transfers phosphatidyl choline (PC) compared to phosphatidyl inositol (PI), was purified 827-fold from rabbit lung homogenate. Incorporation of cholesterol in unilamellar vesicles reduced the PC transfer activity of PLTP_R. Dipalmitoyl phosphatidyl choline uptake by alveolar type II cells was increased in the presence of the protein, and further enhanced in the presence of surfactant liposomes. However, a decrease in uptake was noted with cholesterol in host membranes. Incorporation of PI into host membranes had a low stimulatory effect on the process. All these effects were more pronounced in adult type II cells compared to premature, term and 3-day-old pups. Received 12 September 2001; accepted 11 October 2001     

Development of rhythmic melatonin synthesis in cultured pineal glands and pineal cells isolated from chick embryo

The chick pineal gland exhibits circadian rhythms in melatonin synthesis under in vivo and in vitro conditions. A daily rhythm of melatonin production was first detectable in pineal glands isolated from chick embryos at embryonic day 16 and incubated under a LD cycle. All pineal glands isolated from 17-day-old and older embryos were rhythmic while no gland isolated at embryonic day 14 and 15 exhibited a daily rhythm in melatonin synthesis. Melatonin production in static cultures of embryonic pineal cells was rhythmic over 48 h if the cells were kept under a LD cycle. When embryonic pineal cells were incubated in constant darkness the rhythm in melatonin production was damped within 48 h. These results suggest that chick pineal cells from embryonic day 16 onwards are photosensitive but that the endogenous component of the melatonin rhythm is not completely developed at that age. A soluble analogue of cAMP stimulated and norepinephrine inhibited melatonin synthesis in cultured embryonic pineal cells. These findings indicate that the stimulatory and inhibitory pathways controlling melatonin synthesis in the mature pineal gland are effective in pineal cells isolated from chick embryos at least 2 days before hatching.     

Pineal N-acetyltransferase depression in rats exposed to heat

Summary Exposure of adult male rats to increased temperature of 33±1°C for 3 and 10 days brought about decreases in pineal N-acetyltransferase activity. These and previous findings of pineal HIOMT inhibition under similar conditions support the postulation of a possible thermoregulatory role for the pineal gland.     

Activation by S-adenosylhomocysteine of norepinephrine and serotonin in vitro uptake in synaptosomal preparations from rat brain.

S-Adenosylhomocysteine (10(-7)-10(-5) M) activated norepinephrine (NE) and serotonin (5HT) in vitro uptake in synaptosomal preparations from rat brain, but did not affect dopamine (DA) uptake. When administered to rats (7 mg/kg i.p.), it has the same effect on in vitro NE and 5HT uptake. It did not affect NE and 5HT release.     

42K spaces in submandibular gland of early postnatal rats: effects of carbachol and transport inhibitors

Equivalent spaces of 42K were measured in fragments of the submandibular gland of 1-, 7-, 14- and 21-day-old and adult rats in the absence and presence of carbachol and the transport inhibitors ouabain and furosemide. The results indicate that the 42K space was increased by carbachol in an ouabain-sensitive manner at all ages studied and that part of the secretagogue-stimulated K uptake occurred by way of a furosemide-sensitive transport system in the latter part of the postnatal period and in the adult.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Continuous administration of leukotriene C4 (LTC4, 10(-10) M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10(-9) M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC4 did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC4 (10(-10) M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC4 on LH exocytosis.     

Adenosine uptake in pyrimidine 5'-nucleotidase deficient human erythrocytes via a high affinity transport system

Using a pulse-labeling technique, 14C-adenosine uptake into pyrimidine 5'-nucleotidase (P5N) deficient erythrocytes (RBC) was found to be impaired. The Lineweaver-Burk plot showed Km values of 2.0 X 10(-3) mM and 0.2 X 10(-3) mM for normal RBC and P5N deficient RBC, respectively. These results indicate that P5N is one of regulators of the adenosine transport system and/or is associated with adenosine carrier protein.     

Inhibitory effects of LHRH on ovarian LH receptors in rats]

The administration of LHRH or of its analog [D-Ala6, des-Gly-NH10(2)] LHRH ethylamide to the female rat on day 10 of gestation resulted in termination of pregnancy and in a marked decrease in ovarian LH receptors and plasma progesterone level. Asingle injection of either compound during diestrus I also led to a decrease in LH receptors. These data demonstrate the high sensitivity of the control of ovarian LH receptors by circulating gonadotrophins and suggest that the contraceptive action of pre- and postcoitally administered LHRH is mediated by negative control of LH receptors.     

Maturation of the pineal melatonin rhythm in long- and short-day reared Djungarian hamsters

Male Djungarian hamsters, reared under long (16L/8D) or short (10L/14D) days, were sacrificed at various ages during the day or night, or at night following a 30-min light pulse. The pineal melatonin rhythm matured similarly under long and short days by 20 days of age. The results are discussed in context of the hypothesis that melatonin mediates the photoperiod effects which forestall puberty in short-day reared hamsters.