Type A and type B monoamine oxidase activities in rat brain and liver mitochondria: a comparison of their properties using the non-ionic detergent Triton X-100

1. The effects of the non-ionic detergent Triton X-100 on the heterogeneity of monoamine oxidase activities were studied and compared in synaptic (fractions SM and SM2) and non-synaptic (fraction M) brain mitochondria and liver mitochondria. 2. Triton X-100 inhibited type A and type B monoamine oxidase activities in all four mitochondrial fractions in a concentration-dependent manner. Liver mitochondrial enzymatic activities were much more sensitive to this inhibition than those of brain mitochondria. The activities in the SM fraction of synaptic brain mitochondria were the least susceptible. 3. In all four mitochondrial fractions, type A activities were more sensitive to inhibition than type B activities. 4. These results suggest that the membrane micro-environment around the enzyme molecules in situ may be important in the functional expression of the activity of the enzyme.

The effects of chronic manganese feeding on the activity of monoamine oxidase in various organs of the developing rat

1. Chronic manganese feeding of rat with doses as high as 10 mg/ml in drinking water had no effect on body weight increases during postnatal development. The organ weight increases in brain, liver, heart and kidney also remained unaffected, but spleen weight was consistently lower than in the age-matched controls after Mn-feeding, being more marked at the higher doses. An increase in the Mn concentration to 20 mg/ml led to drastic body weight losses not unlike that seen in malnutrition. 2. There were differential developmental changes in monoamine oxidase (MAO) with respect to tissue type and substrate used. Manganese feeding did not affect the developmental patterns of MAO in brain, heart and kidney. However, hepatic MAO activities towards 5-HT and BzNH2 were found to increase after 10--15 days of postnatal life. 3. In contrast, the activity in the spleen towards 5-HT was lower in the high Mn-treated group in the first few days post-partum.

Energy-metabolizing enzymes in brain regions of adult and aging rats

The regional enzyme activities of glucose metabolism in the rat brain were investigated. Hexokinase (EC 2.7.1.1) and pyruvate dehydrogenase (EC 1.2.4.1), key enzymes for glucose metabolism, showed no changes in activity in all the regions studied of the aging brain as compared with the adult brain. However, the activity of D-3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) is low throughout the adult brain and, in contrast with hexokinase and pyruvate dehydrogenase, its activity decreases significantly during aging. Other enzymes that showed significant decreases during aging are aldolase (EC 4.1.2.13), lactate dehydrogenase (EC 1.1.1.27), citrate synthase (EC 4.1.3.7), and NAD+-linked isocitrate dehydrogenase (EC 1.1.1.41). The catabolic enzyme in cholinergic metabolism, acetylcholinesterase (EC 3.1.1.7), selected as an example of a non-energy-metabolising enzyme, also showed significant decreases in all regions of the brain in aging, although its highest activity remained in the striatum. These results are discussed with respect to the energy metabolism in various brain regions and their status with aging.

The nuclear oestrogen receptor in the female rat. Effects of oestradiol administration during the oestrous cycle on the uterus and contrasting effects of progesterone on the uterus and hypothalamus

Oestradiol administration to immature or ovariectomized rats has been reported to increase the uterine content of long-term nuclear oestrogen receptors. However, in the intact adult female rat, oestradiol administration did not increase the concentration of long-term nuclear oestrogen receptors at all phases of the oestrous cycle. Progesterone administration to rats in late dioestrus did not affect the concentration of uterine nuclear oestrogen receptors 24 h later, although it did prevent the normal cyclic increase at pro-oestrus in the concentration of hypothalamic nuclear oestrogen receptors. Our results therefore show that in the intact adult rat, factors other than the concentration of progesterone or oestradiol determine the nuclear concentration of oestrogen receptors in the uterus. They also demonstrate differences between neural and non-neural tissues in the regulation of oestrogen-receptor interactions.

The regional distribution of monoamine oxidase activities towards different substrates: effects in rat brain of chronic administration of manganese chloride and of ageing

The effects of chronic manganese chloride administration (1 mg MnCl2.4H2O/ml of drinking water) and ageing on the regional distribution of monoamine oxidase (MAO, EC 1.4.3.4) were studied in 2-month- and 24-28-month-old rats. In both the control and Mn-treated rats, the serotonin oxidation (type A) rates decreased in hypothalamus, pons and medulla, striatum, midbrain and cerebral cortex, but not in cerebellum, in ageing. On the other hand the benzylamine oxidation (type B) rates in hypothalamus, striatum and cerebral cortex increased in ageing. In all regions except the cerebellum, there was a uniform decrease in the A/B ratio. This decrease was verified by differential inhibition studies using clorgyline and L-deprenyl, specific type A and type B inhibitors respectively. The dopamine-oxidising rates decreased in all regions, except the cerebral cortex and the cerebellum, in ageing control rats. This age-related decrease was not seen in the striatum and midbrain of manganese-treated rats. In these rats the other effect was an age-related increase in the rate of oxidation of all the amines in the cerebellum, not observed in control rats. These selective effects of manganese are only seen when comparing age-related changes in both groups of animals, since comparison of manganese-treated rats with age-matched controls showed a significant difference only in the rate of serotonin oxidation in the cerebellum of 2-month-old rats. The relationship of these observations to the effects of ageing and manganese encephalopathy on specific amine systems is discussed.

Hypothalamic neurons in dissociated cell culture: the mechanism of increased survival times in the presence of non-neuronal cells

Rat hypothalamic neurons were cultured in the presence of fluorodeoxyuridine to inhibit nonneuronal cell proliferation. Under these conditions, neuronal cell survival was dependent on contact with homologous nonneuronal cells. This phenomenon did not seem to be due to the release of diffusable trophic factors, since neither growth on polylysine in the close proximity of nonneuronal cells nor the use of preconditioned medium significantly increased neuronal survival. However, metabolically active cell layers were required, since growth on heat-killed or fixed homologous nonneuronal cells did not increase neuronal survival. The increased survival of neurons seen here in the presence of homologous nonneuronal cells therefore appears to be due to metabolic co-operation mediated by specific, direct cell-cell contact.

Selective inhibition of L-glutamate and gammaaminobutyrate transport in nerve ending particles by aluminium, manganese, and cadmium chloride

AlCl3, MnCl2, and CdCl2 inhibited the rates of accumulation of [14C] L-glutamate and [3H] gammaaminobutyrate (GABA) in purified rat forebrain nerve-ending particles in a dose-dependent fashion. The concentrations that would give 50% inhibition (IC50) of GABA transport were 316 muM, 7.4 mM, and 1.4 mM, respectively. Ca2+ (1 mM) enhanced the inhibitory effect of Al3+ (IC50 decreased to 149 muM) but antagonized that of Mn2+ (IC50 = 10 mM) and Cd2+ (IC50 = 2.1 mM). For glutamate transport 1 mM Ca2+ changed the IC50 values from 299 to 224 micron for Al3+, 7.1 to 10 mM for Mn2+, and 2 to 3 mM for Cd2+. In contrast, the rates of accumulation of [14C] 2-deoxy-glucose and [3H] L-phenylalanine were mostly unaffected by these metal ions. The results indicate that Al3+, Mn2+, and Cd2+ exerted selective and differential effects on the transport systems of neurotransmitter substances in the synaptosomal membrane.

The relationship of the oestrogen and progestin receptors in the abnormal uterus of the adult anovulatory rat. Effects of neonatal treatment with testosterone propionate or clomiphene citrate

The neonatal administration of testosterone propionate to Wistar rats resulted in anovulatory adults in persistent vaginal oestrus. Clomiphene citrate had a similar effect. In both groups of adults, hyperplasia of the uterine epithelium and occasional metaplasia was observed. The uterine nuclear and cytosol oestrogen and progestin receptors of these anovulatory rats were found to have affinities for their respective ligands similar to those of normal females. The nuclear oestrogen receptor comprised occupied and unoccupied components, as in normal females. The content of the nuclear oestrogen receptor was comparable with that of females in the late dioestrous or pro-oestrous phase. This content was higher in the clomiphene-treated group. Despite the relatively high nuclear oestrogen receptor content the content of progestin receptors, a putative index of the oestrogenic response, was lower in the treated rats than in normal adult females throughout the cycle. Administration of oestradiol to both treatment groups resulted in depletion of cytosol oestrogen receptor content 1 h later, which, however, was not reflected by an increase in the content of nuclear oestrogen receptors. There was no measurable increase in progesterone receptor content in treated rats after daily administration of oestrogen (5 microgram/rat) for 3 days. These changes in sex-hormone-receptor interactions involving an impairment of the normal oestrogenic response may be associated with the abnormal differentiation of the uterus in these sterile, anovulatory animals.

Chromatin organization in the rat hypothalamus during early development

The organization of chromatin in neuronal and glial nuclei isolated from different brain regions of rats during development was studied by digestion of nuclei with micrococcal nuclease. A short chromatin repeat length (approx. 176 base-pairs compared with that of glial nuclei from foetal cerebral cortex (approx. 200 base-pairs) was present in hypothalamic neurons throughout the ages studied, which was similar to the repeat length of cortical neurons from 7- and 25-day-old animals (approx. 174 base-pairs). Whereas in cortical neurons the chromatin repeat length shortened from approx. 200 base-pairs in the foetus to approx. 174 base-pairs in the first postnatal week, the short chromatin repeat length of hypothalamic neurons was already present 2 days before birth, indicating that hypothalamic neurons differentiate earlier than cortical neurons during brain development.

Developmental changes in the composition of polyadenylated RNA isolated from free and membrane-bound polyribosomes of the rat forebrain, analysed by translation in vitro

Free and membrane-bound polyribosomes were isolated from the rat forebrain during its development. Polyadenylated RNA [poly(A)+ RNA] was isolated from both fractions, by using oligo(dT)-cellulose chromatography, and its composition studied by translating the poly(A)+ RNA in vitro in reticulocyte lysates. Electrophoretic analysis of the translation products showed that both free and membrane-bound polyribosomal poly(A)+ RNA gave many common components, but that there were also distinct differences in the protein composition of the products of the two fractions. Several proteins, of mol.wts. 39 000, 37 000, 31 000, 27 000 and 17 000, appeared to be products predominantly of free polyribosomal poly(A)+ RNA, whereas others, of mol.wt. 47 000, 33 000, 24 000 and 21 000 were specific to the membrane-bound polyribosomal poly(A)+ RNA fraction. More developmental changes were observed in the translational products of the membrane-bound poly(A)+ RNA fraction. Proteins of mol.wts. 33 000 and 21 000, which were predominant components of the translational products of this fraction when isolated from 10-day and older rats, were not present in translational products derived from preparations isolated from 3-day-old rats. The developmental appearance of these proteins as translational products of the membrane-bound poly(A)+ RNA suggests the appearance of new mRNA species. These transcriptional changes are discussed in relation to processes involved in brain differentiation, including myelination.

Brain regional distribution of glutamic acid decarboxylase, choline acetyltransferase, and acetylcholinesterase in the rat: effects of chronic manganese chloride administration after two years

Rats were treated chronically with manganese chloride from conception onward for a period of over 2 years in order to study the effects of manganese and aging on the activities of glutamic acid decarboxylase (GAD), choline acetyltransferase (ChAT), and acetylcholinesterase (AChE) in hypothalamus, cerebellum, pons and medulla, striatum, midbrain, and cerebral cortex (which included the hippocampus). Manganese-treated 2-month-old and 24- to 28-month-old rats and age-matched controls were studied. In control rats during aging the activities of GAD decreased in hypothalamus (19%), pons and medulla (28%), and midbrain (22%) whereas the activities of AChE decreased in all regions (20-48%), particularly in the striatum (44-48%). Changes in ChAT activities in aging were observed only in one region-a decrease (23%) in the striatum. Life-long treatment with manganese appeared to abolish partially the decreases in aging in AChE activities in hypothalamus, cerebellum and striatum, and striatal ChAT activity. Manganese treatment also seemed to abolish the age-related decreases GAD activities, since GAD activities in various brain regions of manganese-treated senescent rats were not significantly different from those of control young rats. These results are discussed in relation to other metabolic changes associated with aging and manganese toxicity.

The unoccupied nuclear oestradiol receptor in the rat uterus and hypothalamus during the oestrous cycle

The nuclear oestrogen receptor population in the rat uterus contained an unoccupied receptor component that bound oestradiol with the high affinity (Kd congruent to 0.5 nM) characteristic of oestrogen receptors. This unoccupied receptor was present at all phases of the oestrous cycle. Its content changed in parallel with that of the total nuclear receptor during the cycle. Oestradiol administration to the immature rat resulted in increases in the uterine content of long-term nuclear receptors (i.e., those still present 8 h after administration); these increases were due to occupied oestrogen receptors, since the content of unoccupied receptor was unchanged. Our previous experiments [White & Lim (1980) Biochem. J. 190, 833-837] have shown in contrast, that oestradiol administration results in an increase in the content of unoccupied nuclear receptor in the hypothalamus. However, as in the uterus, similar cyclic changes in the content of unoccupied nuclear receptor occurred in parallel with those of the total nuclear receptor population in the hypothalamus. Differences and similarities between the unoccupied nuclear receptor of the uterus and hypothalamus are briefly discussed.

Infected late false aneurysm of the deep femoral artery

A false aneurysm may mimic an abscess, but concomitant existence of the two lesions seems not to have been previously described. In a 32-year-old man, a false aneurysm of the deep femoral artery was found to be in communication with an abscess cavity in the posterolateral thigh. The false aneurysm was found in the proximity of the protruding tip of a Steinmann pin which had eroded the arterial wall. The abscess was a consequence of posttraumatic and postoperative osteomyelitis which had been previously debrided, bone grafted, and immobilize with an external fixator attached to four Steinmann pins. The condition was successfully treated by surgical drainage of te abscess cavity, excision of the false aneurysm, and ligation of the deep femoral artery.

Alterations in progesterone receptors in the rat uterus bearing an intra-uterine device during the oestrous cycle and early pregnancy

The binding characteristics, content and intracellular distribution of cytosolic and nuclear progesterone receptors have been investigated, using [3H]progesterone as ligand, in the rat uterus bearing a unilateral intra-uterine device (IUD) during the oestrous cycle and from days 3 to 6 of pregnancy. The dissociation constants of nuclear and cytosolic progesterone-receptor complexes for IUD-containing and control uterine horns were similar. Cytosolic receptor concentrations in the IUD-containing uterus were always lower but changed in a manner similar to the control during the periods studied. Nuclear receptor concentrations in the control horn reflected changes in hormone levels during the oestrous cycle although concentrations measured were greater than previously reported. However, in IUD-containing uteri the pattern was completely reversed with minimal levels at pro-oestrus. Nuclear receptor concentrations were little different in both horns during early pregnancy. Total progesterone receptor synthesis determined between metoestrus and pro-oestrus in IUD-containing horns was significantly less than that of control horns. This correlated with the attenuated rise of nuclear oestrogen receptor levels previously observed between these times in IUD-containing uterine horns.

Effect of an intra-uterine device on intracellular relationships of the uterine oestrogen receptor, particularly during pregnancy

The presence of an intra-uterine device in the rat results in a lower nuclear concentration of the oestrogen receptor in the treated horn at pro-oestrus when it is compared with the contralateral control horn. This effect was also seen after the administration of hyperphysiological doses of oestradiol and when the horn was exposed in vitro to high concentrations of oestradiol. The cyclic changes during the oestrous cycle in the activity of the oestrogen-induced enzyme peroxidase were similar in the treated and control horns. These observations have discounted the possibility that the relatively lower nuclear receptor content in the treated horn at pro-oestrus was due to a decreased exposure to oestrogen. A significantly lower nuclear content was also observed in the treated horn on days 4 and 5 of pregnancy. This was not associated with a deficiency in cytosol receptor content which increased concurrently with that of the control horn in the 6 days of pregnancy that were studied. The proportional content of the putative cytosol factor implicated in receptor translocation was similar in both horns, increasing on days 4 and 6 in concert with reported changes in 'induced protein' synthesis. There appeared to be reduced levels of nuclear receptor at a time when blastocyst implantation normally occurs.

The effects of oestrogens and progesterone on oestrogen receptors in female rat liver

The administration of oestradiol-17 beta or ethynyloestradiol as well as the synthetic progestogen norethisterone acetate resulted in translocation of the oestrogen receptor. Progesterone and the synthetic progestogen (+)-norgestrel were ineffective. The increases in nuclear oestrogen receptor content 1 h after injection of each steroid were similar but different subsequently. The increase with oestradiol-17 beta extended for 3--6 h and for at least 9 h with ethynyloestradiol. With norethisterone acetate, nuclear content was still increased after 24 h. Oestrogen injection resulted in cytosol receptor depletion and a 'deficit' in receptor content extending for 6 h, whereas norethisterone acetate-induced translocation was quantitative. With injections of norethisterone acetate + ethynyloestradiol the increase at 1 h and retention of the nuclear receptors were similar to that with norethisterone acetate alone. In contrast, the depletion of cytosol receptor and its restoration were similar to that seen with ethynyloestradiol alone, suggesting that norethisterone acetate did not interfere with the oestrogen receptor replenishment. Specific binding in vitro of [3H]oestradiol-17 beta in liver cytosols was inhibited by (+)-norgestrel and norethisterone acetate, but not progesterone, at concentrations of 10--100 microM. Nuclear receptors present after norethisterone acetate injection bound oestrogen with high affinity (Kd = 1.52 nM), similar to receptors of oestrogen-injected animals. In the uterus, differential retention of nuclear receptors in response to oestrogens is associated with different cellular responses. The differences in the response of the receptor system in liver to the various steroids suggests that the corresponding tissue responses may also be dissimilar. These results are discussed in relation to the problems of liver dysfunction in oral-contraceptive users.

Unoccupied nuclear oestrogen receptors in the female rat hypothalamus. Increases on oestrogen administration

A major proportion of the hypothalamic nuclear oestrogen receptors were available for complexing with radioactive oestradiol in vitro at 4 degrees C and were apparently unoccupied . At 6 h after oestradiol administration the content of unoccupied nuclear receptors had increased 2.5-fold and represented 71% of the total nuclear receptor content. These results suggest that unoccupied receptors may be active elements in the 'long-term' receptor population of the hypothalamus. Androgenized females had lower contents of these receptors.

A comparison of the relationships between progestin receptors and oestrogen receptors in neural and non-neural target tissues of the rat during the oestrous cycle

Similar cyclic changes in the content of nuclear oestrogen receptor occurred in the hypothalamus, cerebral cortex, uterus and pituitary during the oestrous cycle. The relationship of the unoccupied to the total nuclear oestrogen receptor at each phase was similar in all these tissues. However, cyclic changes in the content of the cytosol progestin receptor occurred only in the uterus and pituitary (where they paralleled changes in the nuclear oestrogen receptor), but not in the hypothalamus or cerebral cortex.

Nucleo-cytoplasmic relationships of oestrogen receptors in rat liver during the oestrous cycle and in response to administered natural and synthetic oestrogen

Oestrogen receptors were measured in the cytosolic and purified nuclear fractions of rat liver. Both cytosolic and nuclear receptors bind oestrogen with high affinity (Kd = 1.47 and 2.28 nM respectively) and specificity similar to that of receptors in order oestrogen-target tissues such as the uterus. During the 4-day oestrous cycle the receptor content and distribution between cytosol and nucleus did not vary; in particular, the content of nuclear receptor did not appear to fluctuate in concert with known cyclic changes in the concentration of plasma oestrogen. Injection of 50 micrograms of oestradiol-17 beta or 10 micrograms of ethynyloestradiol resulted in a 4--6-fold increase in the nuclear receptor content, with a concomitant decrease in the unoccupied-receptor content of cytosol 1 h after injection. The nuclear receptors present after injection bind oestrogens with similar affinity (Kd = 2.78 nM) and specificity to receptors present in uninjected animals. The administration of lower doses of either oestrogen was less effective in producing increases in nuclear receptor content. Hence there is apparently substantial translocation of receptor to the nucleus in response to hyperphysiological doses of oestrogen, but not to the physiological changes in plasma oestrogen concentrations during the oestrous cycle. The response to exogenous oestrogens is discussed in relation to the clinical use of synthetic oestrogens and progestogens.

Developmental changes in the protein and ribonucleic acid components of rat brain messenger ribonucleic acid-protein particles isolated from free polyribosomes by oligo(dT)-cellulose chromatography

A study has been made of the developmental changes that occur in the RNA and protein moieties of mRNA-protein particles isolated from newborn and adult rat forebrain free polyribosomes. mRNA-protein particles were isolated by oligo(dT)-cellulose chromatography from salt-washed polyribosomes dissociated by puromycin/0.5 M-KCl treatment as two fractions (E1 and E2) by using Tris/HCl/NaCl eluting buffers containing respectively 25 and 50% (v/v) formamide. Isopycnic centrifugation on CsCl gradients showed that the newborn-derived fractions E1 and E2 has buoyant densities of 1.48--1.50 and 1.41--1.43 g/cm3. Adult-derived E1 and E2 fractions had corresponding values of 1.47 and 1.42 g/cm3. The pooled mRNA-protein particles from the E1 and E2 fractions after deproteinization with proteinase K sedimented with a mean size of approx. 18 S on a sucrose gradient containing 85% formamide with little differences between mRNA molecules from newborn and adult. The mean lengths of the poly(A) segments were similar, being about 130 nucleotides long. Distinct changes were found in the protein composition of the mRNA-protein particles. Fractions E1 and E2 from the newborn contained two major proteins of mol.wts. 74 000 and 52 000 with differences in the relative proportions in each fraction. In contrast, adult fractions E1 and E2 contained predominantly the larger protein. However, the adult fraction E2 contained a more heterogeneous population of minor bands of proteins, including that of mol.wt. 52 000. The findings are discussed briefly in relation to other changes in the developing brain.