Human Brain Phenol Sulfotransferase: Biochemical Properties and Regional Localization

Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of catecholamines and phenol and catechol drugs. The human blood platelet contains a thermolabile (TL) form of PST that catalyzes the sulfate conjugation of dopamine and other monoamines and a thermostable (TS) form that catalyzes the sulfate conjugation of micromolar concentrations of phenol and p-nitrophenol. Experiments were performed to determine whether the brain contains forms of PST analogous to the TL and TS forms found in the human platelet, and to determine whether there are regional variations in human brain PST activity. We found that the human brain contains at least two forms of PST, forms that are similar to the platelet TS and TL forms of the enzyme with respect to substrate specificity, apparent Km constants, thermal stability, and sensitivity to inhibitors. Optimal conditions were determined for the measurement of these two activities in brain homogenates. The stability of PST activities in the human brain after death was determined in five samples of cerebral cortex that were obtained during clinically indicated neurosurgical procedures. An average of 76 +/- 8% and 80 +/- 9% (mean +/- SEM) of the basal TL and TS PST activities, respectively, remained in these five samples of cerebral cortex after 8 h of storage under simulated post-mortem conditions. Six human brains were then obtained less that 8 h after death from patients who had no neurological disease prior to death. The mean activities of the TL and TS forms of PST were measured in 17 different regions of the six brains. If the pituitary was excluded from consideration, TL and TS PST activities both varied approximately fivefold among these regions, and both activities were highest in cerebral cortex. However, the average TS activity in the anterior pituitary, a tissue of non-neural origin embryologically, was 6.5-fold greater than the highest average TS PST activity found in cerebral cortex.     

Distribution and properties of aldehyde dehydrogenase in regions of rat brain

Abstract: NAD-dependent aldehyde dehydrogenases (EC 1.2.1.3) were isolated from various subcellular organelles as well as from different regions of rat brain. The mitochondrial, microsomal, and cytosolic fractions were found to contain 40%, 28%, and 12%, respectively, of the total aldehyde dehydrogenase (5.28 ± 0.44 nmol NADH/min/g tissue) found in rat brain homogenate when assayed with 70 μ. M propionaldehyde at pH 7.5. The total activity increased to 17.3 ± 2.7 nmol NADH/min/g tissue when assayed with 5 m M propionaldehyde. Under these conditions the three organelles contained 49%, 23%, and 9%, respectively, of the activity. The enzyme isolated from cytosol possessed the lowest K _m. The molecular weight of the enzyme isolated from all three subcellular organelles was ∼100,000. Four activity bands were found by electrophoresis of crude homogenates, isolated mitochondria, or microsomes on cellulose acetate strips. Cytosol possessed just two of the forms. The total activity was essentially the same in homogenates obtained from cortex, subcortex, pons-medulla, or cerebellum. Further, the enzyme had the same molecular distribution and total activity in each of these four brain regions. Disulfiram was found to be an in vivo and in vitro inhibitor of the enzymes obtained from these brain regions. Mercaptoethanol, required for the stability of the enzyme, reversed the inhibition produced by disulfiram. The effect was greater for enzyme isolated from cytosol than from mitochondria. Calculations led to the prediction that aldehydes such as acetaldehyde are oxidized in cytosol.     

Presynaptic Nicotinic Cholinergic Receptors Labeled by [3H]Acetylcholine on Catecholamine and Serotonin Axons in Brain

Nicotinic cholinergic receptor binding sites labeled by [3H]acetylcholine were measured in the cerebral cortices, thalami, striata, and hypothalami of rats lesioned by intraventricular injection of either 6-hydroxydopamine or 5, 7-dihydroxytryptamine. In addition, [3H]acetylcholine binding sites were measured in the cerebral cortices of rats lesioned by injection of ibotenic acid into the nucleus basalis magnocellularis. [3H]Acetylcholine binding was significantly decreased in the striata and hypothalami of both 6-hydroxydopamine- and 5,7-dihydroxytryptamine-lesioned rats. There was no change in binding in the cortex or thalamus by either lesion. Ibotenic acid lesions of the nucleus basalis magnocellularis, which projects cholinergic axons to the cortex, did not alter [3H]acetylcholine binding. These results provide evidence for a presynaptic location of nicotinic cholinergic binding sites on catecholamine and serotonin axons in the striatum and hypothalamus.     

Insulin Binding in Four Regions of the Developing Rat Brain

Specific insulin binding has been demonstrated in partially purified membranes prepared from four regions of the developing rat brain. Insulin binding to brain membranes demonstrated kinetics and hormonal specificity that were quite similar to those reported for traditional insulin target tissues (e.g., liver and adipose tissue), and binding was significantly correlated with receptor concentration. Binding in the olfactory bulbs, cerebrum, cerebellum, and hypothalamus all reached highest values at 15 days of postnatal life, with the olfactory bulbs generally showing the greatest binding at all ages studied. A temporal relationship was found between insulin binding to brain membranes in the postnatal rat and plasma membrane protein synthesis, especially in the cerebellum and olfactory bulbs.     

Ontogenetic development of corticotropin-releasing factor (CRF)-containing neural elements in the brain of the chicken during incubation and after hatching

Summary In chicken embryos of different ages and in young chickens after hatching, neural elements reacting with antibodies generated against synthetic ovine corticotropin-releasing factor (CRF) were studied by means of the peroxidase-anti-peroxidase (PAP) technique at the lightmicroscopic level. CRF-immunoreactivity was first observed in perikarya located in the periventricular part of the hypothalamus on the 14th day of the incubation period. CRF-containing neural elements were detected on the same day of incubation in the external zone of the median eminence, but not in all investigated animals. In extrahypothalamic sites, immunoreactive perikarya were demonstrable in the central gray of the mesencephalon on the 15th day of incubation. Furthermore, immunoreactive cells appeared in other brain regions such as nucleus accumbens and dorsomedial nucleus of the thalamus after hatching. The present observations provide information regarding the functional development of the hypothalamo-hypophyseal-adrenal axis in the chick embryo.     

The influence of androgen administration on the structure and function of the brain-pituitary-gonad axis of sexually immature platyfish,Xiphophorus maculatus

Summary This report demonstrates that the administration of testosterone (T) or 11-ketotestosterone (11-KT) to sexually immature (8 wks old) male platyfish (Xiphophorus maculatus) of early-and late-maturing genotypes affects the synthesis and/or release of luteinizing hormone-releasing hormone (LHRH), as assessed by immunocytochemical evaluation, increases the number and activity of pituitary gonadotropes, stimulates the production of sperm and, thus, advances the age of sexual maturation over that dictated by the genome. We also show that 11-KT and T affect different LHRH-containing centers in the brain and have differential effects on rate and degree of sexual maturation, regardless of whether the hormones are administered to early or late-maturing genotypes.     

内蒙东部地区绵羊中华双腔吸虫生物学和流行病学的研究

中华双腔吸虫(Dicrocoelium chinensis Tang et Tang,1978)的生活史虽经研究,但本吸虫在第二中间宿主及终末宿主体内发育的情况尚未经阐明(唐崇惕等,1980).内蒙科右前旗附近数个旗县是本吸虫的流行区,1980—1981年我们在那里进行本项工作,从     

The Taung endocast: a reply to Holloway

Indices of rostrality (ir, ir') are developed to assess the extent to which the medial end of the lunate sulcus (L) is rostrally positioned in photographs and figures of lateral views of primate brains and endocasts, and indices are determined for chimpanzees, SK 1585 and the Taung endocast. Ir quantifies the extent of rostrality as it has traditionally been viewed (in A-P projections) while ir' takes dorsal curvature into account. The ir of the feature that I have identified as the lunate sulcus of Taung is within one standard deviation of the mean ir for Pan and its ir' is within 1.5 standard deviations from the mean ir' for Pan. Both findings are compatible with my earlier statement that the medial end of the lunate sulcus of the Taung endocast is in a pongid-like position. Use of stereoplotting to transfer the position of L from chimpanzee endocasts and brains to australopithecine endocasts is critically assessed: Holloway stereoplotted five chimpanzee brains and then transferred their mean coordinates that describe the lunate sulcus to the Taung endocast. If stereoplotting successfully transfers the extent to which L is rostrally located, one would expect the mean L of Pan and its transferred counterpart in Taung to have identical index values of rostrality. However, the ir of the lunate sulcus that Holloway located on Taung is over two standard deviations lower than the mean ir for the five chimpanzees he stereoplotted to determine its angular coordinates, and Holloway's ir' for Taung is one standard deviation lower than the five chimpanzees' mean ir'. These discrepancies are shown to be due to shape differences, and it is concluded that stereoplotting should not be used to transfer sulci between differently shaped endocasts without correcting for these differences. I also reply to Holloway's criticisms of my use of L/H indices, palpation, techniques for sampling endocasts, and illustration of the Taung endocast. It is shown that there is room on the Taung specimen for the lateral end of L, and the pongid-like sulcal pattern of Taung is reaffirmed. Thus, we do not yet know when human-like sulcal patterns first appeared in the hominid fossil record.     

Characterization, development, and localization of the deoxycytidine phosphorylating systems in mammalian brain

The accumulation of deoxycytidine by rabbit and mouse brain was studied in vitro. Brain slices from brain stem, cerebellum, and forebrain of rabbits of various ages (1 day to 2.5 years) and forebrain from adult mice were incubated for various times in artificial CSF containing 6 nM [3H]deoxycytidine at 37 degrees C under 95% O2/5% CO2. Rabbit and mouse brain slices of all ages accumulated [3H]deoxycytidine by a saturable system (IC50 = 4 microM) and converted it to [3H]deoxycytidine phosphates and [3H]DNA. When slices from all brain regions of 1-day-old rabbits were incubated in 6 nM [3H]deoxycytidine for 30 min, tissue-to-medium ratios of 3H were between 1.2 and 2.5 and declined with age, except in cortex; the percentages of total 3H in perchloric acid homogenates of brain slices as [3H]DNA were 10-24% and declined to low levels in middle age. However, at all ages and in all regions tested, 30-85% of the [3H]deoxycytidine within the slices was phosphorylated. After homogenization and subcellular fractionation of the brain slices incubated in [3H]deoxycytidine for 30 min, the highest percentage of [3H]deoxycytidine phosphates plus [3H]DNA was present in the nuclear and mitochondrial fractions of all brain regions. Deoxycytidine phosphates were synthesized from deoxycytidine in all brain regions tested into middle age.     

Cerebral Blood Flow and Oxidative Metabolism in Conscious Fischer-344 Rats of Different Ages

Abstract: The cerebral metabolic rates for O₂ and for glucose were measured in conscious, fasted male Fischer-344 rats at the ages of 3, 12, and 24 months, and cerebral blood flow was determined with ¹⁴C-iodoantipyrine. The metabolic rates for oxygen and glucose were obtained by multiplying blood flow by the O₂ and glucose concentration differences, respectively, between blood in the femoral artery and in the superior sagittal sinus. Mean cerebral blood flow and the metabolic rates for oxygen and glucose did not differ significantly (p > 0.05) between 3 and 12 or between 12 and 24 months. Nor did the arteriovenous differences for O₂ and for glucose change significantly with age. Because the superior sagittal sinus drains blood mainly from the cerebral cortex, the results indicate that average cerebral cortical oxidative metabolism, and the coupling ratios between the cerebral metabolic rate for oxygen and cerebral blood flow and between the cerebral metabolic rate for glucose and cerebral blood flow, do not change significantly with age in the Fischer-344 rat.