Immunohistochemical demonstration of serotonin-containing nerve fibers in the hypothalamus of the monkey,Macaca fuscata

Summary The distributional pattern of serotonin-containing nerve fibers in the hypothalamus of the monkey (Macaca fuscata) was analyzed with the use of the peroxidaseantiperoxidase method in conjunction with a highly sensitive and specific anti-serotonin serum. The highest concentrations of serotonin-immunoreactive varicose fibers were found in the nucleus praeopticus medialis, nucleus ventromedialis hypothalami, and the complex of mammillary nuclei (nucleus praemamillaris, supramamillaris, mamillaris medialis et lateralis). However, the nucleus suprachiasmaticus, where numerous serotoninergic fibers have been reported to occur in the rat, appeared to be almost devoid of these fibers. The infundibular stalk, and the intermediate and posterior lobes of the pituitary contained considerable numbers of immunoreactive fibers. The present study provides a morphological basis for possible clarification of the influence of serotoninergic projections on various neuroendocrine mechanisms in primates. Furthermore, an attempt was made to clarify the differences and similarities concerning the distributional patterns of serotoninergic nerve fibers within the monkey hypothalamus in contrast to the rat hypothalamus.Supported by grants (No. 56440022, 57214028) from the Ministry of Education, Science and Culture, Japan     

Localisation of substance P-like immunoreactivity in the ciliary ganglia of monkey (Macaca fascicularis) and cat: a light- and electron-microscopic study

The present study describes substance P-like immunoreactivity in the ciliary ganglia of monkey (Macaca fascicularis) and cat. About 60% of neurons in the monkey ciliary ganglion and 40% in the cat ciliary ganglion were substance P-like immunoreactive, ranging from faint to moderate staining. Substance P-like immunoreactivity was located in cell bodies, dendritic profiles and axons. In the monkey, substance P-like immunoreactive pericellular arborisations were associated with about 0.5%–3% of the ganglion cells, which were either negatively, faintly or moderately stained. An electron-microscopic study demonstrated the presence of either substance P-like immunoreactive positive or negative axon terminals synapsing or closely associated with positive dendritic profiles in both the monkey and cat ciliary ganglia. The results suggest that substance P plays an important role in the ciliary ganglion, perhaps as a modulator or transmitter.     

Fluorescence microscopy of the catecholamine-containing neurons of the hypothalamohypophyseal system

Summary The hypothalamohypophyseal system of the mouse, rat, guinea-pig, cat, dog and monkey (Macaca mulatta) was studied with the fluorescence method for catecholamine-containing neurons developed by Falck et al. (1962). The fluorescent fibers are prominent in the external layer and around the primary portal plexus of the infundibulum and in the peripheral region of the neural lobe of these animals, particulary on the external surface and surrounding the primary capillary loops. These fluorescent fibers are connected with fluorescent cells in the arcuate nuclei, and this connection coincides with the tuberohypophyseal system. The neurons of this system have a particular affinity for dopamine, possibly due to their own content of dopamine. In the supraoptic and paraventricular nuclei, no fluorescent cells were found. In the pars intermedia, we also found catecholamine-containing fibers.The presence of catecholamine-containing fibers in the adeno- and neurohypophysis are considered in relation to other data derived from fluorescence and electron microscopy.     

Characteristic pattern of monoaminergic nerve fibers in the pineal organ of the monkey,Macaca fuscata

Summary Monoaminergic nerve fibers were studied in the pineal organ of the monkey, Macaca fuscata, by use of fluorescence and immunohistochemical procedures. Abundant formations of noradrenergic nerve fibers were observed in the pineal organ. They entered the parenchyma in the form of several coarse bundles via the capsule in the distal portion of the organ and spread throughout the organ after branching into smaller units. The density of the autonomic innervation decreased gradually toward the proximal portion of the organ. In the distal portion, numerous nerve fibers formed perivascular plexuses around the blood vessels and some fibers ran as bundles unrelated to the blood vessels in the stroma. Fine varicose fibers and bundles derived from these plexuses penetrated among the pinealocytes. However, only a few intraparenchymal fluorescent fibers were detected in the proximal third of the gland. With the use of serotonin antiserum serotonin-immunoreactive nerve fibers were clearly restricted to the ventroproximal part of the pineal organ. Although the somata of the pinealocytes showed intense immunoreactivity, their processes were not stained. In one exceptional case, clusters of pinealocytes displaying very intense immunoreactivity were found in an area extending from the distal margin of the ventral portion of the pineal stalk to the proximal portion of the pineal organ proper; these cells were bipolar or multipolar and endowed with well-stained processes.     

On the anatomical organization of the vagal nuclei

The neurons of origin of the right vagus and its components in both the monkey (Macaca fascicularis) and albino rats were localized by the retrograde transport of horseradish peroxidase (HRP) applied to the stomach wall, the vagal trunk and its recurrent laryngeal branch. An attempt was also made to localize the neurons forming the superior laryngeal nerve and those supplying the thoracic organs by a combination of operative procedures. The results showed that the stomach was innervated by neurons distributed throughout the entire rostrocaudal extent of the dorsal motor nucleus (DMN) on both sides of the brain stem. Neurons scattered throughout the entire extent of the DMN and nucleus ambiguus (NA) supplied the thoracic viscera. There did not appear to be any topographic arrangement in the DMN neurons supplying the abdominal and thoracic viscera as reported by other workers, and there was no clear evidence of crossing of vagal fibers in the monkey brain stem, though such crossing was seen in the rat brain stem. Both the superior and inferior ganglia of the vagus nerve were labeled following application of HRP to the vagal trunk. Neurons in the caudal part of the NA gave rise to fibers in the ipsilateral recurrent laryngeal nerve, at least on the right side. The neurons giving rise to the superior laryngeal nerve could not be delineated in this study. In all the experimental procedures described, the hypoglossal nucleus was labeled only after applying HRP to the hypoglossal nerve.     

Different effects of cholinergic agents on responses recorded from the cat visual cortex and lateral geniculate nucleus dorsalis

We investigated the effect of cholinergic agents on the cat visual evoked potentials (VEPs) recorded from the primary visual cortex (V1) and lateral geniculate nucleus dorsalis (LGNd) to determine on which level of the visual pathway the cholinergic system acts. VEPs to the alternation of 0.1 cycles per degree sinusoidal gratings at 1 and 4 Hz were recorded from N₂O-anesthetized cats directly from the surface of V1 and LGNd. The depth of recording in LGNd was determined by the site where the maximal response was obtained by 1 Hz stimulation. VEPs to 4 Hz stimulation, which showed sinusoidal waveforms and were analyzed by fast Fourier transforms, were used as indicators for modulation by cholinergic agents. Physostigmine, an acetylcholinesterase inhibitor, 0.7 mg/kg i.v., suppressed the amplitude of the responses more at V1 (suppression ratio: mean±SD, 85.4±9.3%) than at LGNd (32.4±30.7%) (P<0.05). Conversely, scopolamine, a muscarinic receptor blocker, 0.7 mg/kg i.v., increased the amplitude of the responses more at V1 (enhancement ratio: mean±SD, 60.3±22.3%) than at LGNd (−22.2±22.5%) (P<0.05). These results indicate that the V1 changes reflect a direct cortical cholinergic effect, probably by modulating the cholinergic projection from the nucleus basalis of Meynert to V1.     

Experimental anatomical considerations of the dorsal root entry zone lesions for pain relief

Dorsal root entry zone (DREZ) lesions were made in the cervical dorsal horn in cat and monkey. Terminal degeneration was observed in the lateral cervical nucleus in cat and contralateral VPL in monkey by Fink-Heimer stain. WGA-HRP was injected in the cervical dorsal horn of cat and retrograde labelled cells were observed mainly in the raphe nucleus, parabrachial nucleus, locus coeruleus, K?lliker-Fuse nucleus, Eddinger-Westphal nucleus, and hypothalamic area, indicating that these descending fiber systems are involved by the DREZ lesion. The functional role of these fibers in regard to deafferentation pain relief seems now to be open to discussion.     

An autoradiographic and electron microscopic study of retino-hypothalamic connections

Summary Retino-hypothalamic connections have been studied autoradiographically in the rat, guinea pig, rabbit, cat and monkey following the intravitreal injection of ³H-leucine or ³H-proline, and electron microscopically following unilateral eye removal in the guinea pig and monkey. In each of the species examined evidence has been found for a direct projection from the retina to the suprachiasmatic nucleus, but to no other region of the hypothalamus. The projection to the suprachiasmatic nucleus is always bilateral (even in the albino guinea pig, in which all other components of the retinal projection are crossed) but from grain counts in our autoradiographs it appears that the input to the contralateral nucleus is about twice as heavy as that on the ipsilateral side. Most of the retinal fibers appear to terminate within the ventral part of the nucleus where they form asymmetric synapses either upon small dendritic branches or dendritic spines. The possible role of this retinal projection to the suprachiasmatic nucleus in mediating a variety of light-induced neuroendocrine responses is discussed.This work was supported in part by Grants 5 PO1 EY-00491 and 5 RO1 EY-00599 from the National Eye Institute, by U.S.P.H.S. Grant HD 02274, and by Regional Primate Center Grant RR 00166.We should like to thank Mrs. Lue-Vurn Bell, Mrs. Bente Noble, Mrs. Gay Anderson and Mrs. Ludelle Moe for their excellent technical assistance, and Miss Lynn Rogers for her help with the illustrations.     

Hb bali (Macaca) β80 (EF 4) Asn→Lys: The first hemoglobin variant found in the crab-eating monkey (Macaca fascicularis) on Bali Island,Indonesia

A variant hemoglobin due to structural change in the β chain was found in the central part of Bali island, Indonesia, during field studies on the genetic variation of the Indonesian crabeating monkey (Macaca fascicularis), and was named Hb Bali (Macaca). Structural analysis yielded the following results. (1) The amino acid sequence of the normal β chain of the crab-eating monkey coincided with that of the Japanese monkey (M. fuscata) and the pig-tailed monkey (M. nemestrina). (2) Asn at the 80th position from the amino terminal of the β chain was substituted by Lys in Hb Bali. This substitution appeared to have little harmful effect on the carrier, since the hematological characteristics of the heterozygous carriers were not different from those of normal individuals.     

Peptide-containing nerve fibers in the circumvallate papillae.

The occurrence and distribution of an array of neuropeptides and dopamine-beta-hydroxylase in the circumvallate papillae of monkey, pig, cow, ferret, cat, rat and mouse was studied by immunocytochemistry. The animals were chosen to represent species with different diets. Substance P/neurokinin A- and calcitonin gene-related peptide-containing fibers were numerous in the circumvallate papillae of all animals examined, with the highest frequency in monkey, pig, cow, rat and mouse; in ferret and cat moderate numbers were detected. Vasoactive intestinal peptide/peptide histidine isoleucine amide-containing fibers were numerous in the circumvallate papillae of pig, while they were moderate in number in monkey, ferret and mouse. Neuropeptide Y-containing fibers were few to moderate in number in the circumvallate papillae of all species. Galanin-containing fibers were numerous in the pig circumvallate papillae, while only a few fibers could be detected in monkey, cow, cat, rat and mouse. Somatostatin-containing fibers were seen only in the cat circumvallate papillae, gastrin-releasing peptide-containing fibers in the cow and cat, cholecystokinin/gastrin-containing fibers in the pig and cow. Dopamine-beta-hydroxylase-containing fibers were detected in all animals studied. They were few to moderate in number in the circumvallate papillae. There was no obvious link between the peptidergic innervation pattern and the food habits.     

Initial processing of visual information within the retina and the LGN

The initial stage of information processing by the visual system reduces the information contained in the continuous image on the retina into a discrete set of responses which are carried from the lateral geniculate nucleus (LGN) to the visual cortex.-1. The optimal sampling of the light intensity distribution in the visual environment is achieved only if each channel in the visual pathways carries undistorted information corresponding to an image element. The visual system approaches as closely as possible the scheme of optimal spatial sampling, retaining the full information on the low spatial frequency content of the object light intensity. The ideal receptive field of a sustained LGN cell is then of the form J ₁ (Kr)/Kr.-2. The experimentally determined receptive fields of sustained LGN cells (and to some extent retinal ganglion cells as well) in cat closely resemble the functional form J ₁ (Kr)/Kr. The centre-surround organization of the receptive fields is therefore understood as a scheme which leads to a maximal information flow through the visual pathways.-3. The optimal sampling scheme cannot be realized by the retina alone, because of restrictions on the size of neural networks. It is therefore constructed in two stages, ending at the LGN level. A recombination of ganglion cell signals into optimal receptive fields is a major role of the LGN.     

Localization of corticotropin-releasing factor immunoreactivity in the brain of the teleost Sparus aurata

The distribution of perikarya and fibers containing corticotropin-releasing factor (CRF) was studied in the brain of the teleost Sparus aurata by immunocytochemistry using the peroxidase-antiperoxidase method. Antisera against rat CRF, arginine vasotocin, and human adrenocorticotropin (ACTH) were used. Most CRF-immunoreactive neurons were located in the nucleus lateralis tuberis, but they were absent from the nucleus preopticus, which only contained arginine vasotocin neurons. Few CRF perikarya were identified in the nucleus preopticus periventricularis and in the mesencephalic tegmentum. A conspicuous bundle of immunoreactive fibers ran along the diencephalic floor and pituitary stalk to end near the cells of the hypophysial pars intermedia. No CRF was seen near the adenohypophysial rostral pars distalis. Our results suggest that, in Sparus aurata, CRF is a releasing factor for melanotropic cells. Its role as a releasing factor for ACTH is discussed.     

The location of spinothalamic axons within spinal cord white matter in cat and squirrel monkey

The locations of spinothalamic (STT) fibers in the spinal cord white matter have been identified in cat and squirrel monkey by light-microscopic visualization of labeled fibers following multiple thalamic injections of wheatgerm agglutinin conjugated to horseradish peroxidase. Thalamic injections were combined with either a constricting dural tie or an intraspinal injection of colchicine to facilitate axonal labeling at more rostral spinal levels. In the cat, the ventral-to-dorsal distribution of labeled STT fibers was bimodal. In the ventrolateral white matter, labeled axons were coarse in nature and were primarily concentrated peripherally. In the dorsolateral white matter, labeled STT axons consisted of fine-caliber fibers concentrated in the ventral portion of the dorsolateral funiculus and were equally distributed throughout the medial and lateral white matter. In the squirrel monkey, the distribution of STT fibers was unimodal, extending from the ventral surface of the spinal white matter to the ventralmost portion of the dorsolateral funiculus. As in the cat, however, the ventrally located axons were large and coarse and were primarily located in the peripheral white matter, whereas the dorsalmost STT fibers were of fine caliber and were distributed equally in the medial and lateral white matter.     

Immunohistochemical demonstration of serotonin nerve fibers in the olfactory bulb of the rat,cat and monkey

Summary The distribution of serotonin (5-HT) positive fibers in the olfactory bulb of the rat, cat and monkey was studied using the peroxidase-anti-peroxidase (PAP) immunohistochemical method and highly specific antibodies to 5-HT. In general, 5-HT fibers were present throughout all layers in the olfactory bulb of these species except for the olfactory nerve layer and different as well as restricted laminar patterns of 5-HT distribution were observed. There were also species-related differences in the pattern of 5-HT distribution, in each layer. The most notable species difference was apparent in the glomerular layer of the main olfactory bulb. In case of the rat and cat, a very dense plexus of 5-HT fibers was observed to be diffuse in the glomerulus, while in the monkey, the distribution of 5-HT fibers was scanty and partial, as was seen in the accessory olfactory bulb of the rat.This work was supported by grant (No. 56440022) from the Ministry of Education, Science and Culture, Japan     

Kinetics of low threshold calcium channels of relay cells in cat lateral geniculate nucleus

Kinetics of the low threshold T-type Ca2+ channel is studied with single electrode voltage damp technique on brain slices of the cat lateral geniculate nucleus (LGN). Space damp is dramatically improved by blocking various K+ and Na+ channels, decreasing Ca2+ current and selecting proper holding potentials. Results from this study are similar to those obtained from acutely dissociated LGN neurons of the rat, indicating that the kinetics of T-Ca2+ channels of the cat LGN neurons is the same as that of the rat LGN. The result reported previously on the cat LGN may result from a defect in space damp.     

The distribution of corticotropin-releasing factor-immunoreactive neurons and nerve fibers in the brain of the snake,Natrix maura

Summary The anatomical distribution of neurons and nerve fibers containing corticotropin-releasing factor (CRF) has been studied in the brain of the snake, Natrix maura, by means of immunocytochemistry using an antiserum against rat CRF. To test the possible coexistence of CRF with the neurohypophysial peptides arginine vasotocin (AVT) and mesotocin (MST) adjacent sections were stained with antisera against the two latter peptides. CRF-immunoreactive (CRF-IR) neurons exist in the paraventricular nucleus (PVN). In some neurons of the PVN, coexistence of CRF with MST or of CRF with AVT has been shown. Numerous CRF-IR fibers run along the hypothalamo-hypophysial tract and end in the outer layer of the median eminence. In addition, some fibers reach the neural lobe of the hypophysis. CRF-IR perikarya have also been identified in the following locations: dorsal cortex, nucleus accumbens, amygdala, subfornical organ, lamina terminalis, nucleus of the paraventricular organ, nucleus of the oculomotor nerve, nucleus of the trigeminal nerve, and reticular formation. In addition to all these locations CRF-IR fibers were also observed in the lateral septum, supraoptic nucleus, habenula, lateral forebrain bundle, paraventricular organ, hypothalamic ventromedial nucleus, raphe and interpeduncular nuclei.     

Efferent projections from the lateral septal nucleus to the anterior hypothalamus in the rat: A study combining Phaseolus vulgaris-leucoagglutinin tracing with vasopressin immunocytochemistry

Summary The tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) was injected into the lateral septum of the rat at different rostrocaudal locations to study the efferent septal projections to the anterior hypothalamus. For spatial correlation of these septofugal elements with the vasopressinergic system a dual immunocytochemical technique was used (i) to demonstrate nerve fibers and their corresponding bouton-like structures labeled with the tracer, and (ii) to identify vasopressin in the same section. The hypothalamic paraventricular and supraoptic nuclei, the accessory hypothalamic magnocellular system, and the suprachiasmatic nucleus are recipients of PHA-L-labeled fibers from all parts of the lateral septum. Close appositions between (i) these axons and their varicosities, and (ii) vasopressin-immunoreactive perikarya and their processes, putatively indicating functional interrelationships, were observed in all these nuclear areas, especially in their neuropil formations.Abbreviations F fornix - OC optic chiasm - OT optic tract - PVN paraventricular nucleus - SCN suprachiasmatic nucleus - SON supraoptic nucleus - III third ventricle     

Immunocytochemical study of the hypothalamic magnocellular neurosecretory nuclei of the snake Natrix maura and the turtle Mauremys caspica

Summary An immunocytochemical study of the magnocellular neurosecretory nuclei was performed in the snake Natrix maura and the turtle Mauremys caspica by use of antisera against: (1) a mixture of both bovine neurophysins, (2) bovine oxytocin-neurophysin, (3) arginine vasotocin, and (4) mesotocin. Arginine vasotocin- and mesotocin-immunoreactivities were localized in individual neurons of the supraoptic and paraventricular nuclei, with a distinct pattern of distribution in both species. The same cells appeared to be stained by the anti-oxytocin-neurophysin and anti-mesotocin sera. The supraoptic nucleus can be subdivided into rostral medial and caudal portions. In N. maura, but not in M. caspica, neurophysin-immunoreactive neurons were found in the retrochiasmatic nucleus. No immunoreactive elements were seen in the suprachiasmatic nucleus of both species after the use of any of the antisera. A dorsolateral aggregation of neurophysin-containing cells, localized over the lateral forebrain bundle, was present in both species. Magnocellular and parvocellular neurophysin-immunoreactive neurons were present in the paraventricular nucleus of both species. In the turtle, the paraventricular neurons were arranged into four distinct layers parallel to the ependyma; these neurons were bipolar with the major axis perpendicular to the ventricle, and many of them projected processes toward the cerebrospinal-fluid compartment. In N. maura a group of large neurons of the paraventricular nucleus was found in a very lateral position. The posterior lobe of the hypophysis and the external zone of the median eminence contained arginine vasotocin- and mesotocin-immunoreactive nerve fibers. The lamina terminalis of both species was supplied with a dense bundle of fibers containing immunoreactive neurophysin. Neurophysin-immunore-active fibers were also present in the septum, some telencephalic regions, including the cortex and the olfactory tubercule, in the paraventricular organ, and the periventricular and periaqueductal gray of the brainstem.This work was partially supported by a Grant S-85-39 from the Direccion de Investigaciones, Universidad Austral de Chile to E.M. Rodriguez     

Simultaneous Recording of Input and Output of Lateral Geniculate Neurones

TO understand the way in which the cat dorsal lateral geniculate nucleus (LGN) processes visual information it would be useful to know the number and type of retinal inputs to individual LGN neurones. Using electrical stimulation of the optic nerve Bishop et al.¹concluded that an impulse in a single optic nerve fibre is sufficient to excite a single LGN neurone. From the appearance of excitatory postsynaptic potentials (EPSPs) recorded essentially intracellularly, Creutzfeldt suggested that LGN neurones are driven by perhaps one² or a few³ retinal ganglion cells. Hubel and Wiesel⁴ proposed models of convergence of several retinal inputs on single LGN neurones based on analyses of receptive fields. Guillery⁵ produced anatomical evidence that some types of LGN neurones receive inputs from several different retinal fibres. Now we report direct observations which were made by recording simultaneously from single LGN neurones and from individual retinal ganglion cells which provided excitatory input to them. We shall not consider inhibitory influences, which are currently under study.     

Distribution of FMRFamide-like immunoreactivity in the central nervous system of the Formosan monkey (Macaca cyclopsis)

The distribution of FMRFamide-like immunoreactivity in the central nervous system of the Formosan monkey (Macaca cyclopsis) was investigated employing immunohistochemical techniques. FMRFamide-containing cells were found to be widely distributed throughout the forebrain. Principal densities of FMRFamide neuronal perikarya were observed in the following areas: the amygdaloid complex, the olfactory tubercle, the cerebral cortex, the basal ganglia, the septum, the caudate-putamen and the arcuate nucleus. A large number of immunoreactive fibers were observed in areas ranging from the cerebral cortex to the spinal cord, and were noted in the following locations: the preoptic area, the tuberal and posterior hypothalamic areas, the bed nucleus of the stria terminalis, the nuclei of the spinal trigeminal nerve, the hypoglossal nucleus, the nucleus of the solitary tract, and the dorsal horn of the spinal cord. The results generally parallel those described in the rat and guinea pig.