Regional distribution of choline acetyltransferase and acetylcholinesterase within the amygdaloid complex and stria terminalis system

The distribution of "marker" enzymes for cholinergic neurons has been studied in 10 subdivisions of the amygdaloid complex of the rat brain. Choline acetyltransferase activity was measured using a radiochemical method in samples dissected from fresh serial sections. Acetylcholinesterase was studied using a histochemical procedure. Both enzymes had similar patterns of distribution within the amygdaloid complex and were most concentrated in the posterior lateral and basolateral nuclei and in the nucleus of the lateral olfactory tract. These enzymes were much less concentrated in the cortical, medial, central, and basomedial nuclei. Large differences in acetylcholinesterase staining were found within the lateral posterior and the basolateral nuclei and within the pyriform cortex. Biochemical studies showed a parallel distribution of choline acetyltransferase within these nuclei. The results indicate that cholinergic neural elements in the amygdala are concentrated primarily in the basolateral complex and suggest that this region may be innervated by cholinergic fibers traveling in the ventral amygdalo-fugal pathway.

Microperoxisome distribution in the central nervous system of the rat

The distribution of microperoxisomes was studied in areas of the central nervous system having high concentrations of catecholaminergic neurons and in areas lacking this neuron type, using the alkaline DAB cytochemical method for catalase. Substantial numbers of microperoxisomes are found in neurons in the locus coeruleus and in nucleus A1 of the medulla, as well as in the substantia nigra, whereas few catalase-reactive bodies are seen in neurons of the cerebrum and cerebellum. The number of catalase-reactive microperoxisomes per unit area in the catecholaminergic neurons of the CNS is comparable to the number seen previously in neurons of the peripheral cervical sympathetic ganglia. Some spinal cord neurons also contain reactive microperoxisomes. Catalase-reactive microperoxisomes are numerous in oligodendrocytes of all areas studied, and in ependymal cells bordering the third and fourth ventricles. Astrocytes contain few reactive structures in the cytoplasm near the nucleus, but they are readily found in astrocytic processes and end-feet.

Remarkable electron-microscopic localization of thiamine diphosphate phosphohydrolase (TDPase) in the tanycytes of the rat

The electron-microscopic localization of TDPase in the tanycytes of rat brain was studied. The reaction product was demonstrated in the membranes, but not in the Golgi apparatus of this cell type. Possible functional aspects of these findings were discussed.

Monoamine oxidase localization in the ependyma and infundibular recess in the catfish Clarias batrachus and its probable significance

The presence of monoamine oxidase (MAO) in the cerebrospinal fluid (CSF) and MAO positive tracts bridging the CSF and the subependyma strongly suggest the involvement of CSF in the neuroendocrine control of hypophysial function.

The locus coeruleus: a cytoarchitectonic, Golgi and immunohistochemical study in the albino rat

The locus coeruleus of the adult albino rat is a clearly delimited nucleus in Nissl-stained preparations. It is surrounded by an extensive, relatively neuron-free neuropil which is not stained in reduced silver and Luxol fast blue preparations. Most if not all locus coeruleus neurons contain the enzyme dopamine-beta-hydroxylase (DBH) and are thus presumably adrenergic. Two general classes of medium-sized neuron were found in the locus coeruleus in Nissl- and DBH-stained material: multipolar and somewhat smaller fusiform cells. The nucleus was divided into dorsal and ventral parts cytoarchitectonically; the two are distinguished in that (a) fusiform rather than multipolar cells predominate in the dorsal division, (b) cells in the dorsal division are more densely packed, and (c) a majority of the cells in the dorsal division are aligned obliquely in a dorsolateral to ventromedial orientation when viewed in the frontal plane, and longitudinally (anteroposteriorly) when viewed in the horizontal and sagittal planes. The locus coeruleus contains an estimated 1643 +/- 21 neurons (+/- S.E.M.; N=12) as determined in Nissl-stained paraffin sections, and 1439 +/- 29 neurons (+/- S.E.M.; N=6) as determined in DBH-stained frozen sections. The latter estimate is less reliable because of some uncertainty about section thickness. The ventral division of the locus coeruleus has an estimated 210 +/- 11 neurons (+/- S.E.M.; N=6). In Golgi-Cox material counterstained with cresyl violet most locus coeruleus neurons could also be classified as multipolar or fusiform, the latter being somewhat smaller. Typically, both types of neuron have relatively long thin dendrites which branch once or twice and extend well beyond the limits of the nucleus into surrounding neuropil and nuclear areas, particularly the mesencephalic nucleus of the trigeminal nerve and pontine central gray. Spines, consisting of a thin stalk of variable length with a small bulb at the end or just a thin stalk, were scattered infrequently but regularly along all dendrites and a majority of the somata of both classes. Very thin locally ramifying axon-like plexuses were impregnated in several locus coeruleus neurons, as were larger (about 3 mum diameter) projecting axons. Only about 0.07% of the locus coeruleus neurons were impregnated in the Golgi-Cox material although a wide range of impregnation times and ages was used.

Catecholamine enzymes in the degenerative neurological disease idiopathic orthostatic hypotension

Discrete brain areas and sympathetic ganglia obtained at autopsy from patients with idiopathic orthostatic hypotension were assayed for tyrosine hydroxylase and dopamine beta-hydroxylase. Dopamine beta-hydroxylase activity was decreased 7.5-fold in sympathetic ganglia, while tyrosine hydroxylase activity was reduced more than 50-fold in the pontine nucleus locus coeruleus. These observations indicate that noradrenergic neurons of both brain and ganglion are affected in idiopathic orthostatic hypotension, but suggest that the central and peripheral biochemical deficits differ.

Time-course variations in tyrosine hydroxylase activity in the rat locus coeruleus after electrolytic destruction of the nuclei raphe dorsalis or raphe centralis

Time-course variations in tyrosine hydroxylase activity were measured in the locus coeruleus of the albino rat after electrolytic coagulation of either the nucleus raphe dorsalis or the nucleus raphe centralis. Highly significant increases were measured at 4 days after lesioning of the raphe dorsalis (30.33%) and the raphe centralis (81.55%) compared with control values, whereas the activity in groups A9 and A10 was unchanged at this time-point. In conjunction with other experimental evidences, an hypothesis is proposed that the catecholaminergic neurons located in the locus coeruleus are directly and/or indirectly controlled by the serotonin-containing neurons located in the anterior raphe system nuclei.

Vascular and brain dopamine beta-hydroxylase activity in young spontaneously hypertensive rats

Dopamine beta-hydroxylase activity was higher in mesenteric vessels, adrenal glands, and serum of 3-week-old spontaneously hypertensive rats but lower in the locus coeruleus than it was in the control Wistar-Kyoto rats. The results support the concept that the nervous system is an important regulator of blood pressure.

The localization of acetylcholinesterase in the locus coeruleus of the normal rat and after 6-hydroxydopamine treatment

The locus coerulus is a densely packed group of neurons in the floor of the fourth ventricle, and is the largest aggregate of noradrenaline-containing cells in the mammalian brain. The distribution within the locus of acetylcholinesterase (AChE), which is present in high concentration, has been studied at light and electron microscope level, both in normal rats and in ones treated with 6-hydroxydopamine. Neuronal enzyme activity is entirely intracellular and mainly concentrated in stacks of ER which occupy much of the cell cytoplasm. There are no indications of a cholinergic input. After 6-hydroxydopamine treatment extensive cell death occurs and AChE activity virtually disappears. A majority of the many blood vessels in the locus also stain strongly for AChE, unlike those present in most other areas of the rat brain. The locus coeruleus therefore represents an area of the rat brain with a high content of AChE, but no evidence of a cholinergic mechanism. Some possible explanations for this anomalous presence of AChE are briefly discussed.

Reversible changes in the accumulation and activities of tyrosine hydroxylase and dopamine-beta-hydroxylase in neurons of nucleus locus coeruleus during the retrograde reaction

To examine the biochemical events associated with the retrograde reaction in central noradrenergic neurons, changes in the activities of several enzymes subserving the metabolism of catecholamines, including tyrosine hydroxylase (TH),dopamine-beta-hydroxylase (DBH), DOPA decarboxylase (DDC), and monoamine oxidase (MAO), were measured in the nucleus locus coeruleus of rat brain following transection of the ascending axons from neurons in this nucleus by electrolytic lesions of the posterolateral hypothalamus. Such lesions produced a triphasic response in the activities of TH and DBH consisting of: (a) an increase to approximately 150 percent of control during the first 48 h followed by (b) a reduction reaching 60 percent of control by day 14, and (c) a full recovery of activity by day 21-28. In contrast, the activities of DDC and MAO, enzymes non-specific for catecholamine neurons, were unchanged. Immunochemical titration with specific antibodies to TH and DBH demonstrated that the fall in enzyme activity was entirely attributable to reduced accumulation of specific enzyme protein and not inhibition of pre-existing enzyme molecules. There was no reduction in the number of neurons in the nucleus locus coeruleus as a consequence of the lesion. We conclude that a reduction in the accumulation of specific enzymes subserving transmitter biosynthesis characterizes a reversible retrograde reaction of central noradrenergic neurons. The coincidence of the time course of reduced enzyme accumulation with regenerative sprouting from damaged noradrenergic axons and also the absence of classical signs of chromatolysis in locus coeruleus neurons following comparable lesions suggest that, first, during the retrograde reaction there may be a reordering of priorities governing accumulation of specific proteins favoring accumulation of those required for reconstitution of cellular processes by sprouting at the expense of proteins utilized in the synthesis of neurotransmitters, and second, some intrinsic neurons of the CNS may undergo reversible biochemical changes of a retrograde reaction in the absence of the classical morphological appearance of chromatolysis.

Diffusion of horseradish peroxidase perfused through the lateral ventricle of the chick telencephalon

Horseradish peroxidase, perfused into the lateral ventricle of chick brain, freely and slowly diffuses through the cerebral extracellular spaces. The layer of astrocytic end-feet surrounding blood capillaries does not consitute a barrier to the tracer which permeates the basal lamina, diffuses between the pericytic cells and finally accumulates in the intercellular space beneath the tight junctions between contiguous endothelial cells. No evidence was found for transport by micropinocytotic vesicles from the cerebral parenchyma to the capillary lumen.

Ontogeny of the induction of tyrosine hydroxylase by reserpine in the superior cervical ganglion, nucleus locus coeruleus and adrenal gland

The ontogeny of the induction of tyrosine hydroxylase by reserpine has been studied in the superior cervical ganglion, adrenal gland and nucleus locus coeruleus of the rat. The inductive response developed gradually over a period of days in all 3 areas. However, the onset of induction occurred at markedly different times in these regions, being present from day 2 of life, the earilest time tested, in the adrenal, day 6 in the locus coeruleus and day 24 in the ganglion. In the ganglion even extremely high, toxic doses of reserpine failed to induce the enzyme during the first 3 weeks of life. Decentralization studies indicated that the ganglion was functionally innervated at this time. Moreover, the onset of induction was not time-locked to a specific phase of the postnatal development of tyrosine hydroxylase activity in the areas examined. It is probable that the development of inducibility reflects maturation of mechanisms intrinsic to the adrenergic cell, and this timetable is different for cells in different areas.

Ultrastructural localization of tyrosine hydroxylase in noradrenergic neurons of brain

Tyrosine hydroxylase (EC 1.14.16.2), the enzyme catalyzing the rate-limiting step in catecholamine biosynthesis, was localized by electron microscopy within noradrenergic neurons of the nucleus locus coeruleus of the rat brain with a specific antibody to tyrosine hydroxylase labeled by the peroxidase-antiperoxidase immunohistochemical method. Labeled cell bodies and their processes were easily distinguished from unstained neuronal elements in the neuropil. The hydroxylase was only seen in the neuronal cytoplasm. Its distribution in processes was different from that in cell soma. In longitudinal sections of axons and dendrites, the peroxides reaction product appeared as fiber-like strands aligned parallel with the plasma membrane. In cross section, the labeled structures had a diameter of 220 A and exhibited an orderly distribution within the processes. The size and distribution of the peroxidase-stained structures suggest that they are neurotubules. In the perikarya, the cytoplasm was diffusely stained; the reaction was most intense on membranes of endoplasmic reticulum and Golgi apparatus, whereas lysosomes and mitochondria did not stain. The ultrastructural localization of tyrosine hydroxylase is consistent with biochemical data suggesting that the enzyme exists in different states in cell body and processes. The ultrastructural identification of enzymes subserving synthesis of neurotransmitters in central neurons and their processes may provide a useful tool in mapping the distribution of chemically specific synapses on identifiable neurons in brain.

[Histochemical study of choroid plexuses, ependymal epithelium and subcommissural organ in experimental conditions (author's transl)]

Activities of some dehydrogenases (DH) belonging to the metabolism of glucose, glutamic acid and gamma-aminobutyric acid, and to Kreb's cycle are investigated in choroid plexuses, ependymal epithelium and subcommissural organ of the rat. The observations are completed by detection of acid phosphatase activity. Metabolic modifications are demonstrated following carbonic anhydrase inhibition and plasmatic sodium hypertonicity. After treatment with Diamox, an increase of the activity of the various DH considered is observed in choroid plexuses. The effect seems to be only transient. Plasmatic hypertonicity induces some changes in DH activity in the different tissues. Acid phosphatase activity remains unchanged in these conditions.

Postmortem changes in brain catecholamine enzymes

Postmortem changes in the activities of tyrosine hydroxylase, dopa decarboxylase, and dopamine-beta-hydroxylase were examined in various areas of rat brain. Tyrosine hydroxylase activity decreased in an exponential fashion with a half-time of two to four hours in caudate-putamen, substantia nigra, and locus ceruleus. Dopa decarboxylase activity remained within 20% of control values at five hours in these areas, but then decreased precipitously. Dopamine-beta-hydroxylase activity remained within 20% of control for at least 20 hours after death.