中枢血管紧张素对心血管活动调节作用

血管紧张素(Ang)广泛存在于中枢神经系统和外周组织中,对心血管活动和交感神经活动起重要调节作用。本文介绍了孤束核(NTS)、延髓头端腹侧区(RVLM)、延髓尾端腹侧区(CVLM)和室旁核(PVN)内Ang对心血管活动的影响,Ang对动脉压力感受性反射(ABR)和心交感传入反射(CSAR)的调节作用,肾素-血管紧张素系统的基因敲除研究,以及Ang与高血压和慢性心力衰竭的关系。     

Apomorphine: sterotyped behavior and regional distribution in rat brain.

The distribution of apomorphine following subcutaneous injection of 20 mg/kg (as the hydrochloride) was measured spectrofluorometrically in specific regions of rat brain. Measurable concentrations were found in the brain within a few minutes of injection, the drug was still detectable for at least 60 min in all regions, and maximum concentration was observed 20 min after injection. Stereotyped behavior, characteristic of apomorphine action, followed a time course parallel to accumulation of the drug in the brain.     

Polyamines: developmental alterations in regional disposition and metabolism in rat brain

The polyamines spermidine and spermine and the activity of the polyamine synthesizing enzyme, S-adenosyl-L-methionine (SAM) decarboxylase, were measured in regions of adult rat brains and during postnatal development. In the adult, although spermidine levels tended to correlate with the relative amounts of white matter in some areas, there were striking exceptions. SAM decarboxylase activity of the adult brain was higher than in most other mammalian tissues, although brain levels of polyamines were among the lowest. SAM decarboxylase activity appeared to be localized to cellular cytoplasm. Its activity increased with age in contrast to the levels of spermine, spermidine, DNA and RNA which decreased during postnatal development.     

Physiological role of brain angiotensin III in drinking behavior in the rat

We examined the physiologic role of endogenous brain angiotensin III (AIII), an active degradative product of angiotensin II, in drinking behavior. Adult, male spontaneously hypertensive (SH) and Wistar-Kyoto normotensive (WKY) rats that were instrumented with an intracerebroventricular (i.c.v.) cannula connected to an osmotic minipump for chronic infusion were used. 7-day i.c.v. infusion of the specific AIII antagonist, Ile⁷-AIII (10 or 100 pmol/min), resulted in no significant alteration in daily (24 h), diurnal (8:00 a.m.-8:00 p.m.) or nocturnal (8:00 p.m.-8:00 a.m.) basal water intake in both SH and WKY rats. Similar results were obtained with i.c.v. infusion of the aminopeptidase inhibitor, bestatin (150 or 300 pmol/min), given alone or simultaneously with Ile⁷-AIII (10 pmol/min). Rats that were water-deprived for the first 3 days of 7-day infusion of Ile⁷-AIII consumed significantly less water during the first 2 h after water became available. Furthermore, the accumulated water intake during the first 24 h was appreciably greater in SH than WKY rats. We interpret these results to suggest that the endogenous brain AIII may not be tonically involved in fluid homeostasis. Instead, it must be activated under conditions of dehydration, such as water deprivation, particularly in the SHRs, to initiate drinking behavior.     

Cholesterol esters in developing rat brain: enzymes of cholesterol ester metabolism

Abstract— Three enzymes of cholesterol ester metabolism, a cholesterol-esterifying enzyme which incorporates free fatty acids into cholesterol esters without participation of CoA, and two cholesterol ester hydrolases with differing pH optima, all showed distinct changes in developing rat brains. The specific activity of the esterifying enzyme was approx. 20 percent of the adult level at birth, increased gradually to the adult level by 20 days of age and remained constant thereafter. The pH 4.2 hydrolase at birth also had a specific activity of about 20 per cent of the adult level but it increased rapidly to reach a peak at 13 days, by which time the activity had increased eight-fold. The activity declined somewhat thereafter to reach the adult level by 23–30 days. In contrast, there already was 60 per cent of the adult specific activity of the pH 6.6 cholesterol ester hydrolase at birth. The activity remained constant until 12 days and then doubled during the next two weeks, reaching a broad peak, then declining slightly to reach the adult activity by 50 days. Therefore, the developmental changes of both of the hydrolases appeared to be related to the process of myelination. The period of active myelination (10–30 days) was characterized by the sharp rise in the activity of pH 6.6 cholesterol ester hydrolase and by the rapid decrease of pH 4.2 cholesterol ester hydrolase.     

Divergent mechanism regulating fluid intake and metabolism by the brain renin-angiotensin system

The purpose of this review is two-fold. First, I will highlight recent advances in our understanding of the mechanisms regulating angiotensin II (ANG II) synthesis in the brain, focusing on evidence that renin is expressed in the brain and is expressed in two forms: a secreted form, which may catalyze extracellular ANG I generation from glial or neuronal angiotensinogen (AGT), and an intracellular form, which may generate intracellular ANG in neurons that may act as a neurotransmitter. Second, I will discuss recent studies that advance the concept that the renin-angiotensin system (RAS) in the brain not only is a potent regulator of blood pressure and fluid intake but may also regulate metabolism. The efferent pathways regulating the blood pressure/dipsogenic effects and the metabolic effects of elevated central RAS activity appear different, with the former being dependent upon the hypothalamic-pituitary-adrenal axis, and the latter being dependent upon an interaction between the brain and the systemic (or adipose) RAS.     

Cadmium-induced changes in the activity of carbohydrate metabolism enzymes in mollusks

In the bivalve mollusksCrenomytilus grayanus, Mizuhopecten yessoensis, Mercenaria stimpsoni, andPeronidia venulosa, the activity of hexokinase (HK) and pyruvate kinase (PK), the key enzymes of glycolysis, and of glucose-6-phosphate dehydrogenase (G6PhDH), the main enzyme of the pentose phosphate path, was determined in the presence of heightened cadmium concentrations (500 mg/l). Under the effect of cadmium, the enzyme activity either decreased immediately or underwent an initial increase and decreased later. Such a response is consistent with the general theory of stress and suggests a difference in the adaptive capacities of the mollusks studied.     

Effects of ethanol on the activity of brain enzymes

Ethanol alters, in a selective manner, the activity of several membrane-bound enzymes in the central nervous system (CNS) which are important for neuronal transmission of information. Ethanol inhibits Na+/K+-transporting ATPase activity, while adenylate cyclase (AC) activity is stimulated by ethanol added in vitro. Ethanol's effects on AC activity are mediated primarily via effects on proteins that regulate AC activity. Ethanol has selective effects on monoamine oxidase activity, in that the B form of the enzyme is more sensitive to inhibition by ethanol added in vitro. The selective effects of ethanol on different membrane-bound CNS enzymes may result from differing membrane lipid microenvironments of the enzymes, or from differences in the enzyme proteins per se.     

Disruption of behavior and brain metabolism in artificially reared rats

Early adverse life stress has been associated to behavioral disorders that can manifest as inappropriate or aggressive responses to social challenges. In this study, we analyzed the effects of artificial rearing on the open field and burial behavioral tests and on GFAP, c‐Fos immunoreactivity, and glucose metabolism measured in anxiety‐related brain areas. Artificial rearing of male rats was performed by supplying artificial milk through a cheek cannula and tactile stimulation, mimicking the mother's licking to rat pups from the fourth postnatal day until weaning. Tactile stimulation was applied twice a day, at morning and at night, by means of a camel brush on the rat anogenital area. As compared to mother reared rats, greater aggressiveness, and boldness, stereotyped behavior (burial conduct) was observed in artificially reared rats which occurred in parallel to a reduction of GFAP immunoreactivity in somatosensory cortex, c‐Fos immunoreactivity at the amygdala and primary somatosensory cortex, and lower metabolism in amygdala (as measured by 2‐deoxi‐2‐[¹⁸fluoro]‐d ‐glucose uptake, assessed by microPET imaging). These results could suggest that tactile and/or chemical stimuli from the mother and littermates carry relevant information for the proper development of the central nervous system, particularly in brain areas involved with emotions and social relationships of the rat. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1413–1429, 2017     

Integrating transcriptional activity in genome-scale models of metabolism

Background

Genome-scale metabolic models provide an opportunity for rational approaches to studies of the different reactions taking place inside the cell. The integration of these models with gene regulatory networks is a hot topic in systems biology. The methods developed to date focus mostly on resolving the metabolic elements and use fairly straightforward approaches to assess the impact of genome expression on the metabolic phenotype.

Results

We present here a method for integrating the reverse engineering of gene regulatory networks into these metabolic models. We applied our method to a high-dimensional gene expression data set to infer a background gene regulatory network. We then compared the resulting phenotype simulations with those obtained by other relevant methods.

Conclusions

Our method outperformed the other approaches tested and was more robust to noise. We also illustrate the utility of this method for studies of a complex biological phenomenon, the diauxic shift in yeast.

     

米根霉在氮源限制下的木糖代谢和关键酶特性北大核心CSCD

【目的】解析氮源浓度对米根霉木糖代谢途径及产物的影响,提高木糖利用率。【方法】以木糖为碳源,考察不同氮源浓度下米根霉的生物量、有机酸积累量、木糖代谢关键酶(木糖还原酶、葡萄糖-6-磷酸脱氢酶)活力以及胞内还原力(NADH/NAD+、NADPH/NADP+)的差异。【结果】富氮条件下(2.4 g/L尿素),木糖代谢速率达2.03 g/(L·h),木糖还原酶、葡萄糖-6-磷酸脱氢酶的活力以及胞内还原力较高,生物量达18.01g/L,几乎不积累有机酸;限氮条件下(0.15 g/L尿素),木糖还原酶、葡萄糖-6-磷酸脱氢酶的活力以及胞内还原力水平降低,生物量仅4.02 g/L,富马酸积累量为6.55 g/L,残余木糖量较高;氮源浓度为0.6 g/L时,木糖还原酶和葡萄糖-6-磷酸脱氢酶的活力以及NADPH/NADP+处于前二者之间,此时生物量9.11 g/L,有机酸积累量较大,其中富马酸为12.28 g/L。【结论】充足的氮源可使米根霉通过木糖代谢关键酶与胞内还原力的协同效应强化木糖代谢活力,通过优化氮源浓度后,米根霉可积累更多有机酸。