Cholinoceptive neurons without acetylcholinesterase activity and enzyme-positive neurons without cholinergic synaptic innervation are present in the main olfactory bulb of adult rat.

Light and electron microscopic histochemistry revealed acetylcholinesterase-positive and acetylcholinesterase-negative neurons in the main olfactory bulb of adult rat. Their distribution patterns on various neuron types have been analysed in detail. (1) No acetylcholinesterase staining could be demonstrated in the granule cells which receive a large number of the cholinergic synapses. (2) In contrast, enzyme activity was present in the soma and dendrites in most of the non-cholinergic and non-cholinoceptive relay cells (mitral cells and tufted cells) and in a subset of short-axon interneurons, where cholinergic synapses could not be detected. (3) Within the neuropil of glomeruli, two compartments were present, one of which was free of acetylcholinesterase-positive structures, while many enzyme-positive neuronal elements were seen in the other. (4) Characteristically, cholinergic and non-cholinergic neuronal structures showed triadic arrangements. (5) The axonal release of acetylcholinesterase from cholinergic axons is probable. It is suggested that, in the olfactory bulb, acetylcholinesterase is release by cholinergic afferent axons, and it is the cholinergic synapses that determine which postsynaptic neurons are cholinoceptive rather than the intraneuronal presence of acetylcholinesterase. In the main olfactory bulb, the acetylcholinesterase present in the relay cells therefore appears to have functions other than the hydrolysis of acetylcholine.

Evidence for the neuronal origin of brain capillary acetylcholinesterase activity.

Acute administration of monosodium-L-glutamate (MSG) to rats induces the degeneration of acetylcholinesterase (AChE)-positive neurons of the area postrema (AP). Chronic treatment with MSG results in the disappearance of AChE activity of area subpostrema (ASP) capillaries. It is concluded that processes of AChE-positive AP neurons terminate within the ASP and may contribute to the AChE activity of ASP capillaries.

Morphological evidence for the involvement of calcium in neurohypophysial hormone release.

An elevated intracellular Ca2+ concentration in the secretory nerve endings of the rat neurohypophysis was detected histochemically by means of light microscopy concomitant with the vasopressin secretion evoked by hypertonic saline. The electron microscopic and X-ray microanalytical results furnish morphological evidence for the function-dependent Ca2+ storage capacity of the mitochondria, and suggest their role in the regulation of the free Ca2+ level in the neurosecretory axon terminal.

Neurotoxin induced nerve cell degeneration: possible involvement of calcium.

Neurotoxin induced nerve cell degeneration has been studied in sensory ganglia of newborn and in the area postrema of adult rats following the administration of the selective sensory neurotoxin, capsaicin and the amino acid excitotoxin, glutamic acid, respectively. Light microscopic histochemical, autoradiographic, electroncytochemical and X-ray microanalytical studies revealed that degeneration of certain small-sized, type B primary sensory neurons, induced by capsaicin, was associated with a marked accumulation of calcium predominantly in mitochondria of the damaged ganglion cells. Similarly, monosodium glutamate treatment resulted in the appearance of calcium-containing electron-dense granules in mitochondria of degenerating area postrema neurons. In addition, after a combined administration of 45Ca2+ and capsaicin or monosodium glutamate, significantly higher levels of radioactivity have been detected by liquid scintillation spectroscopy in the Gasserian ganglia and the area postrema, respectively. It is concluded that an enhancement in intracellular calcium level may be intimately involved in the process of neuronal cell death and may represent a common basic mechanism responsible for the development of cellular events leading ultimately to the degeneration of nerve cells.

Calcium-containing mitochondrial granules in neurohypophysial axon terminals disappear following vasopressin treatment of Brattleboro rats.

The presence of intramitochondrial calcium-containing electron-dense granules was demonstrated in axon terminals of chronically hyperactive neurosecretory neurons of untreated homozygous Brattleboro rats. Following vasopressin treatment for 30 days, which has been shown to attenuate this neuronal hyperactivity, calcium-containing deposits could not be detected in mitochondria. It is concluded that the presence of intramitochondrial calcium-containing dense deposits is connected with the functional state of neurosecretory neurons.

[Ultrastructural localization of the acetylcholinesterase (AChE) activity in the diaphragm of the rat embryo (author's transl)]. / Uber die ultrastrukturelle Lokalisation der Acetylcholinesterase- (AChE-) Aktivität im Diaphragma des Rattenembryo.

Electron histochemistry revealed intense AChE activity in the diaphragm of 15 days old rat embryos. The reaction product was localized to the perinuclear cisterna and the cisternae of the sarcoplasmic reticulum of myoblasts. The development of myoneural contacts at day 17 of gestation was preceded by the appearance of AChE activity of muscle cells. Sarcoplasmic cisternae and vesicles in the subjunctional sarcoplasm may play an important role in the development of the AChE activity of the postjunctional sarcolemm.

[Changes in the butyrylcholinesterase activity of fenestrated capillaries in the area postrema during postnatal development]. / Die Veränderungen der Butyrylcholinesterase-Aktivität der fenestrierten Capillaren in der Area postrema während der postnatalen Entwicklung.

Ontogenetic changes in butyrylcholinesterase (BuChE) activity of fenestrated capillaries in the rat Area postrema lying outside of the blood-brain barrier were investigated by means of light and electron microscopic histochemical methods. Marked enzyme activity could be demonstrated in the capillary endothelial cells of the neonatal rat. The intensity of the light microscopically detectable BuChE activity in the capillaries decreased gradually during the postnatal ontogenesis, but the capacity of the enzyme synthesis of the endothelium remained unchanged in the adult rat, too. Our results do not indicate any direct correlation between BuChE positivity of capillaries and the existence of the blood-brain barrier.

[The localization of the acetylcholinesterase in the area postrema and area subpostrema of the rat. Light and electron microscopical investigations (author's transl)]. / Uber die Lokalisation der Acetylcholinesterase in der Area postrema und Area subpostrema der Ratte. Licht- und elektronenhistochemische Untersuchungen

In perfusion fixed material was studied the localization of acetylcholinesterase in the region of rat Area postrema on frozen slides and chopped tissue light and electron microscopically. In the light microscope there was a week reaction in the parenchyma cells of the Area postrema and the capillary endothelium and some nerve fibres of the Area subpostrema. Electron microscopically was demonstrated the AChE in the perinuclear cisterna, in the cisternae of the rough endoplasmatic reticulum and the neurotubuli of the axons and dendrites in the Area postrema. It was also evidenced the AChE-reaction in the pinocytic vesicles of the capillary endothelium, the axons, dendrites and some other structural elements of the neuropil in the Area subpostrema. The results were discussed from the standpoint of the functional morphology.

[Na-glutamate sensitive neurons in the area postrema of the rat (author's transl)]. / Na-Glutamat-sensitive Nervenzellen in der Area postrema bei der Ratte.

A single subcutaneous injection of monosodium-L-glutamate induces severe ultrastructural alterations in certain AChE positive parenchymal cells of the Area postrema of the adult rat. Signs of cellular degeneration include massive intracellular edema, swelling of mitochondria, vacuolization of the cisternae of the rough endoplasmic reticulum and marked alterations in the chromatin pattern of the nucleus. Identification of these cells as neurons is based on the presence of axosomatic synapses.

[Ultrastructural changes in the supraoptica-neurohypophyseal system after induction of lesions in the pituitary stalk in rats]. / Ultrastrukturelle Veränderungen des supraoptico-neurohypophysären Systems nach Läsion des Hypophysenstiels bei der Ratte.

Fine structural changes occurring in the supraoptic nucleus and the neural lobe have been studied in rats following the electrolytic lesion of the hypophysial stalk. Supraoptic neurosecretory neurones undergo a typical chromatolytic reaction. In addition, proliferating microglial cells disconnect axosomatic synapses and phagocytose degenerating neurones. Surviving neurones show signs of structural restitution 3 to 4 weeks after surgery. In the neurohypophysis degeneration of secretory nerve endings started with the disintegration of secretory vesicles 3 to 4 d postoperatively. Degenerated axon terminals were engulfed by pituicytes. Signs indicative of axonal regeneration were not observed in the neural lobe up to the end of the 4th postoperative week.

[Histochemical analysis of the multiple effect of organophosphorous compounds (Wolfatox, DFP) in rats (author's transl)]. / Histochemische Analyse der vielfältigen Wirkungen von Organophosphaten (Wolfatox, DFP) bei Ratten.

In vivo effects of Wofatox and DFP has been studied by light and electron microscopic histochemical methods in the central nervous system, in cardiac and striated muscles of rats. Singleintraperitoneal injection of Wofatox and DFP LD50 resulted in complete inhibition of the histochemically detectable acetyIcholinesterase (AChE) activity in the central nervous system. Various striated muscles exhibit different degrees of sensitivity towards inhibitors, neither can the enzyme activity of some motor end plates be completely inhibited. In addition to AChE inhibition in striated muscles, organophosphorous compounds induce also subacute myopathic changes. In the case of a lethal intoxication, ultra-structural alterations suggesting myocardial lesion can be observed.

Histochemical evidence for the role of Ca2+ and neutral protease in the development of the subacute myopathy induced by organophosphorous compounds.

A temporal and causal relationship has been established between inhibition of acetylcholinesterase (AChE) by organophosphorous compounds, accumulation of Ca2+, an increase of neutral protease activity and the development of the ultrastructural signs of subacute myopathy.

[Subcellular localization of calcium in the neurosecretory axon terminals of the neurohypophysis of the rat following stimulation by administration of hypertonic salt solution]. / Subcelluläre Lokalisation des Calciums in den neurosekretorischen Axonterminalen der Neurohypophyse der Ratte nach Erregung durch die Verabreichung von hypertonischer Kochsalzlösung.

The calcium accumulating capacity of neurohypophysial axon terminals stimulated by the intravenous injection of hypertonic saline has been studied by using light and electron microscopic histochemical methods and X-ray microanalysis. In the stimulated neurosecretory terminals Ca++ containing granules appeared in the mitochondria. Smaller granules of similar morphological appearance occurred in the smooth endoplasmic reticulum as well. It is suggested that the mitochondria and the smooth endoplasmic reticulum are intimately involved in the regulation of the intraaxonal free calcium level during the process of vasopressin secretion.

7-oxo PGI2 dramatically increases the safety margin of digitalis.

In our earlier experiments pretreatment with 7-oxo PGI2 was found to be effective against ouabain induced rhythm disturbances in guinea pigs. Maximal protection appeared 48 hours after a single dose of 50 micrograms/kg administered i.m. In the present study we wanted to clarify how cardiac glycoside induced positive inotropic responses as well as appearance of rhythm disturbances in higher doses were influenced by 7-oxo PGI2 pretreatment in dogs. The experiments were performed on anesthetized, artificially ventilated mongrel dogs weighing 9-11 kg. The ECG, left ventricular pressure, as well as +dP/dtmax and -dP/dtmax were continuously recorded. Ouabain was applied by intermittent infusion, i.e. an initial i.v. dose of 30 micrograms/kg was infused during 5 min followed by a 25 min interval, then 15 micrograms/kg was infused every 10 min for 2.5 min until cardiac arrest. Ouabain induced increasingly severe patterns of rhythm disturbances, ventricular extrasystoles (ES), ventricular tachycardia (VT), ventricular fibrillation (VF) and cardiac arrest (CA). In the case of 7-oxo PGI2 (50 micrograms/kg) pretreatment the dose of ouabain necessary to provoke ES was 62 +/- 5.0 micrograms/kg versus (v.s.) 53.3 +/- 3.4 micrograms/kg in the control group, VT: 97 +/- 5.0 micrograms/kg v.s. 80 +/- 6.2 micrograms/kg and CA: 100 +/- 4.2 micrograms/kg v.s. 87 +/- 7.7 micrograms/kg. In the pretreated group 25% of the maximal positive inotropic effect was produced by 14.2 +/- 3.6 micrograms/kg ouabain v.s. 31.7 +/- 3.6 micrograms/kg. According to the above results 7-oxo PGI2 increases the safety margin of ouabain.

[Significance of low osmolarity contrast media in state of the art roentgen diagnosis]. / Alacsony ozmotikus nyomású kontrasztanyagok jelentösége a korszerü röntgendiagnosztikában.

The authors used low-osmolality contrast material intravascularly in 546 patients, in 371 cases ioxaglate, in 80 patients iopamidol and in 95 iohexol. On each occasion good detail-rich pictures were obtained. Sensation of heat was indicated only by 1 patient (iopamidol), pain by 7 patients (ioxaglate 4, iohexol 2, iopamidol 1). The blood pressure, pulse rate and the UN, SGOT and SeBiru values showed no significant changes. The experiments were carried out on 101 dog kidneys. Selective renal angiography was done with the aforementioned materials and compared with the conventional, high-osmolality materials (iodamide, metrizoate). The histological changes were only slight, of small extent, and reversible when the new materials were used. Use of the new, low-osmolality contrast materials is justified whenever they must be given intravascularly, but it is imperative in the examination of children, patients of high risk groups and sensitive organs (nervous system, kidney, coronary vessels).