Modifications in the distribution of met-enkephalin in the cat spinal cord after administration of clonidine. An immunocytochemical study

We have studied the modifications in the distribution of methionine-enkephalin in the cat spinal cord after intravenous or intrathecal administration of clonidine by using an immunocytochemical technique. In animals not treated with the substance, a very high density of immunoreactive fibers was found in layers I and II; a high density in the dorso-lateral funiculus and in the reticular formation; a moderate density in layers III, IV and V; and a low density in layer VI. However, after intravenous or intrathecal administration of clonidine a decrease in fibers containing met-enkephalin was observed in layers I and II (high or moderate density), the dorso-lateral funiculus, and the reticular formation (moderate or low density), and in layers IV and V (low or very low density). In all cases, the decrease in the immunoreactivity was more marked when clonidine was administered intrathecally. Our results suggest that clonidine induces the release of metenkephalin in the spinal cord. They further suggest that the opioid peptide released could be involved in the control of nociceptive transmission by inhibiting the release of neurotransmitters (e.g., substance P). In summary, our study shows that clonidine could be involved in antinociceptive mechanisms in the cat spinal cord.

Neuropeptides in the cat amygdala

The distribution of seven neuropeptides was studied in the cat amygdala using an indirect immunoperoxidase technique. No labeling was found for luteinizing hormone-releasing hormone or beta-endorphin (1-27). Sparse alpha-melanocyte-stimulating hormone-immunoreactive fibers were found in the basomedial nucleus of the amygdala, whereas a low density of fibers containing alpha-neo-endorphin was observed in the anterior amygdaloid area. Neurotensin was observed in fibers of the anterior amygdaloid area (low density) and both the lateral (low density) and the medial part (moderate density) of the central nucleus. A low density of fibers containing neurokinin A was found in the anterior amygdaloid area, the basolateral nucleus, and the medial part of the central nucleus. A moderate density was observed in the basomedial nucleus and in the medial and cortical nuclei. Fibers containing somatostatin-28 (fragment 1-12) were observed in all the amygdaloid nuclei, whereas immunoreactive cell bodies were found in all the nuclei except in the medial part of the central nucleus and the medial nucleus. Perikarya containing neurokinin A were observed in the latter nucleus. The results point to a discrete distribution of peptidergic fibers in the cat amygdala, as well as the occurrence of neurons containing neurokinin A and somatostatin-28 (fragment 1-12). The distribution of the peptides studied in the cat is compared with the location of the same peptides in the amygdala of other species. The possible diencephalic origin of the peptidergic fibers is also discussed.

Double immunocytochemistry in pre-embedding electron microscopy for the detection of neurotensin and tyrosine hydroxylase in the guinea pig, using two primary antisera raised in the same species

In this study we identified for electron microscopy two different antigens (neurotensin and tyrosine hydroxylase) in the same pre-embedding section of nervous tissue, using two antibodies obtained in the same species. Optimal ultrastructural results were obtained without adding to the fixative either glutaraldehyde or acrolein (normally used for electron microscopy techniques). The different developing methods used in this study (DAB in combination with either 1 nm silver-enhanced colloidal gold or benzidine dihydrochloride) are perfectly distinguishable at the ultrastructural level, and show some advantages over other previously described developing procedures. For instance, the use of small gold particles (1 nm) reduces the severity of membrane damage caused by tissue penetration of the bigger gold particles (5 nm). In addition, the reaction products are stable, so there is no need to stabilize them before osmication, as is necessary in other developing methods such as the TMB procedure. The immunolabeling results obtained in this study were similar in both developing methods, although synaptic profiles were more readily visible when the DAB/colloidal gold procedure was used. Using electron microscopy, we have detected TH immunoreactivity in dendrites and perikarya receiving synaptic contacts from NT-positive terminals, as well as TH-immunoreactive inputs on NT-positive neurons, at both the somatic and dendritic levels.

ACTH/CLIP immunoreactivity in the cat brain stem

The distribution of adrenocorticotropin hormone/corticotropin-like intermediate lobe peptide was studied in the cat brain stem, using an indirect immunoperoxidase technique. No immunoreactive cell bodies were observed. However, a high density of immunoreactive fibers was found in the periaqueductal gray, the dorsal nucleus of the raphe, the locus coeruleus, and the marginal nucleus of the brachium conjunctivum. A moderate density was found in the central linear nucleus, the central tegmental field, the Kolliker-Fuse nucleus, the inferior central nucleus, and the postpyramidal nucleus of the raphe. A low density was found in the superior and inferior colliculi, the interpeduncular nucleus, the nucleus sagulum, the superior central nucleus, the cuneiform nucleus, the accessory dorsal tegmental nucleus, the nucleus of the solitary tract, the dorsal motor nucleus of the vagus, and the paralemniscal, magnocellular, gigantocellular, and lateral tegmental fields. Moreover, single immunoreactive fibers were observed in numerous nuclei of the cat brain stem. In comparison with previous studies carried out in the same region of the cat, as well as the rat and the human, our results point to a more widespread distribution of adrenocorticotropin hormone/corticotropin-like intermediate lobe peptide immunoreactive structures in the cat brain stem. This widespread distribution indicates that the peptide might be involved in several physiological functions of the cat brain stem.

Expression of the beta-isoforms of Na,K-ATPase in the renal cortex of rats

The aim of the present study was to assess the presence of beta1- and beta2-isoforms of the beta-subunit of Na,K-ATPase in the rat renal cortex. This has been accomplished by immunohistochemistry and Western blotting using isoform-specific antisera. Western blot of brain extract, used as positive control, revealed the bands corresponding to beta1- and beta2-glycosylated peptides, with a molecular weight (MW) of approximately 50-60 that, after exhaustive treatment with N-endoglycosidase-F, migrated to the MW corresponding to the core peptides (approximately 35). In the renal cortex, Western blot revealed the bands corresponding to beta1. After deglycosylation of the samples, the bands hybridizing with the anti-beta1-antibodies moved to the MW corresponding to a partially deglycosylated form and the core peptide. Bands with a MW of approximately 50-60 hybridized with anti-beta2, although digestion with endoglycosidase failed to move the band towards a lower MW. Immunohistochemistry revealed the presence of beta1- but not beta2-isoform. Northern blot for total mRNA showed strong signals for beta1 in renal cortex, the mRNA for the beta2-isoform being undetectable. In conclusion, only mRNA and glycopeptide of the beta1-isoform seem to be present in renal cortex of adult control rats.

An immunocytochemical mapping of ACTH/CLIP in the cat diencephalon

Using an indirect immunoperoxidase technique, the location of cell bodies and fibres containing adrenocorticotropin hormone/corticotropin-like intermediate lobe peptide (ACTH/CLIP) was studied in the cat diencephalon. Immunoreactivity was observed in several diencephalic nuclei of the cat in which no immunoreactivity has been previously reported. In this sense, a low density of immunoreactive cell bodies was found in the nucleus ventromedialis hypothalami; a high density of immunoreactive fibres was found in the medial preoptic area; a moderate density in the lateral preoptic area and in the nuclei centralis thalami (pars medialis), interventralis thalami, interanteromedialis thalami, parafascicularis and praemamillaris (pars ventralis and pars dorsalis); a low density in the nuclei habenularis lateralis and reuniens thalami, and single fibres were found in the nuclei lateralis thalami (pars anterior), habenularis medialis, parataenialis, corpus geniculatum mediale, ventralis thalami (pars medialis) and in the fornix. Our results point to a more widespread distribution of ACTH/CLIP immunoreactive structures in the cat diencephalon in comparison with previous studies carried out in the same region of this feline.

An immunocytochemical mapping of beta-endorphin (1-27) in the cat diencephalon

The distribution of beta-endorphin (1-27) immunoreactive cell bodies and fibres was studied in the diencephalon of the cat using an indirect immunoperoxidase technique. In the thalamus, almost all the immunoreactive fibres were found in the midline region and in nuclei located near the midline, whereas in the hypothalamus fibres containing beta-endorphin (1-27) were visualized extending by the whole structure. The hypothalamus showed a higher density of beta-endorphin (1-27) immunoreactive fibres than the thalamus, as well as immunoreactive cell bodies, since in the thalamus no beta-endorphin (1-27) immunoreactive neuron was located. The densest network of immunoreactive fibres was observed in the epithalamus (nucleus periventricularis anterior) and in the hypothalamic nuclei arcuatus, hypothalami ventromedialis, suprachiasmaticus, periventricularis hypothalami, hypothalamus dorsomedialis, area hypothalamica dorsalis, hypothalamus anterior, filiformis, hypothalamus posterior and regio praeoptica. In the hypothalamus, a high density of perikarya containing beta-endorphin (1-27) was observed in the nucleus arcuatus and a low density in the nucleus hypothalami ventromedialis. The distribution of beta-endorphin (1-27) immunoreactive fibres and perikarya is compared with the location of other neuropeptides in the cat diencephalon. Our findings reveal that b-endorphin (1-27) immunoreactive structures are widely distributed in the cat diencephalon, suggesting that the peptide might be involved in several physiological functions.

Mapping of alpha-melanocyte-stimulating hormone-like immunoreactivity in the cat diencephalon

Using an indirect immunoperoxidase technique, we studied the location of alpha-melanocyte-stimulating hormone-like fibers and cell bodies in the cat diencephalon. In the thalamus, almost all the immunoreactive fibers were found in the midline region, whereas in the hypothalamus immunoreactive fibers were observed in the whole structure. The hypothalamus showed a higher density of both immunoreactive fibers and cell bodies; no immunoreactive neurons were found in the thalamus. The densest network of immunoreactive fibers was observed in the epithalamus (nucleus periventricularis anterior) and in the hypothalamic nuclei filiformis, hypothalami ventromedialis, arcuatus, periventricularis hypothalami, area hypothalamica dorsalis, and hypothalamus posterior. A high density of immunoreactive neurons was found in the nucleus arcuatus, in the hypothalamus lateralis, and in the area hypothalamica dorsalis; a low density was found in the nucleus hypothalami ventromedialis and in the hypothalamus dorsomedialis. By comparison with the studies of previous researchers, these data showed a more widespread distribution of alpha-melanocyte-stimulating hormone-like immunoreactive fibers and perikarya in the feline hypothalamus. Moreover, our findings indicate that the peptide is widely distributed in the cat diencephalon, suggesting that alpha-melanocyte-stimulating hormone might be involved in several physiological functions.

Neurotensin and tyrosine hydroxylase in the tuberoinfundibular system of the guinea pig hypothalamus with special emphasis to lactation status

Immunohistochemical methods allowed us to study the distribution of neurotensin immunoreactivity (NT-IR) in the infundibular area of the guinea pig and to obtain evidence of a clear increase of such immunoreactivity in females during lactation. By use of the double immunolabeling method we demonstrated the presence of NT in the tuberoinfundibular dopaminergic (TIDA) neuronal system, in the nerve terminals of the median eminence as well as in the arcuate perikarya. In addition, NT-IR was detected in anterior pituitary cells especially stained in the rostral part of the gland of lactating females. These cells were identified exclusively as gonadotrophs by use of the elution-restaining procedure. These results suggests that NT is able to participate in the modulation by TIDA of prolactin secretion. Moreover, NT production by gonadotrophs could be responsible for other unknown pituitary actions.

Calbindin D-28K-immunoreactivity in the cat diencephalon: an immunocytochemical study

The distribution of calbindin D-28k-immunoreactive fibers and cell bodies in the cat diencephalon has been analyzed by using the avidin-biotin immunoperoxidase technique. The thalamus showed a higher density of immunoreactive cell bodies than the hypothalamus. A high density of both immunoreactive perikarya and fibers was observed in the nuclei pulvinar, geniculatum mediale and laterale, lateralis posterior and dorsalis, habenularis lateralis and medialis, posterior, subparafascicularis, submedius, centralis medialis, medialis dorsalis, ventralis postero-medialis and postero-lateralis, reticularis, centralis lateralis, rhomboidens, paracentralis, ventralis lateralis, anterior and medialis, reuniens, anterior ventralis and medialis, hypothalamus posterior, corpus mamillare, area hypothalamica dorsalis and in the hypothalami ventromedialis. Moreover, a high density of fibers containing calbindin and a moderate/low density of immunoreactive cell bodies was found in the nuclei periventricularis anterior, parataenialis, hypothalamus lateralis, mamillaris lateralis, filiformis, periventricularis hypothalami, hypothalamus anterior and in the suprachiasmaticus.

Distribution of parvalbumin immunoreactivity in the cat diencephalon

The distribution of parvalbumin-immunoreactive cell bodies and fibers in the cat diencephalon has been analyzed by using the avidin-biotin immunoperoxidase technique. The thalamus showed a higher density of immunoreactive cell bodies than the hypothalamus. A high or moderate density of perikarya and a high density of fibers containing parvalbumin was observed in the nuclei lateralis posterior, lateralis dorsalis, pulvinar, corpus geniculatum laterale, reticularis, medialis dorsalis, centrum medianum, subparafascicularis, ventralis postero-medialis, ventralis postero-lateralis, habenularis medialis, parafascicularis, corpus geniculatum mediale, centralis lateralis, rhomboidens, reuniens, centralis medialis, ventralis medialis, ventralis lateralis, parataenialis, anterior ventralis, anterior medialis, ventralis anterior, hypothalamus posterior, corpus mamillare, area hypothalamica dorsalis, and in the nucleus suprachiasmaticus. Moreover, a high or moderate density of immunoreactive fibers and a low density of parvalbumin-immunoreactive cell bodies was observed in the nuclei periventricularis anterior, anterior dorsalis, habenularis lateralis, corpus geniculatum laterale (pars ventralis), periventricularis hypothalami, hypothalamus lateralis, hypothalamus anterior, and in the hypothalamus dorsomedialis.

Distribution of calbindin D-28k-immunoreactivity in the cat brainstem

We studied the distribution of calbindin-immunoreactive fibers and cell bodies in the cat brainstem. The densest clusters of immunoreactive perikarya were found in the inferior and superior colliculi, the inferior olive, the periaqueductal gray, the central tegmental field and the substantia nigra, whereas the central linear nucleus, the locus coeruleus, the nucleus incertus, the dorsal and ventral nuclei of the lateral lemniscus, the cuneiform nucleus, the pontine gray, the Kölliker-Fuse nucleus, the dorsal motor nucleus of the vagus and the medial nucleus of the solitary tract had the lowest density. In the lateral tegmental field, the marginal nucleus of the brachium conjunctivum, the superior central nucleus, the nucleus sagulum, the dorsal nucleus of the raphe, the interpeduncular nucleus and the retrorubral nucleus the density of immunoreactive cell bodies was moderate. A high density of immunoreactive fibers was observed in the substantia nigra, the nucleus ruber, the superior and inferior colliculi, the periaqueductal gray, the interpeduncular nucleus, the central, magnocellular and lateral tegmental fields, the marginal nucleus of the brachium conjunctivum, the postpyramidal nucleus of the raphe, the inferior olive, the internal division of the lateral reticular nucleus and the medial and lateral nuclei of the superior olive. A moderate density of calbindin-immunoreactive fibers was found in the retrorubral nucleus, the central linear nucleus, the locus coeruleus, the nucleus sagulum, the dorsal nucleus of the raphe, the cuneiform nucleus, the ventral and dorsal nuclei of the lateral lemniscus, the medial nucleus of the solitary tract, the dorsal motor nucleus of the vagus, and the cuneate nucleus. Other brainstem regions such as the area postrema, the external division of the lateral reticular nucleus, the nucleus ambiguus, the nucleus intercalatus, the nucleus incertus, the pyramidal tract and the trapezoid body had the lowest density of immunoreactive fibers.

Galanin-like immunoreactivity in the cat brainstem

The distribution of galanin-like immunoreactive fibers and cell bodies has been studied in the cat brainstem. Perikarya containing galanin were only found, at a low density, in the nucleus of the brachium of the inferior colliculus and in the pericentral nucleus of the inferior colliculus. The highest density of immunoreactive fibers was found in the laminar spinal trigeminal nucleus and in the parvocellular division of the alaminar spinal trigeminal nucleus. A moderate density of immunoreactive fibers was observed in the periaqueductal gray, locus coeruleus, marginal nucleus of the brachium conjunctivum and below the facial nucleus, whereas a low density of such fibers was found in the nucleus of the brachium of the inferior colliculus, pericentral nucleus of the inferior colliculus, nucleus incertus, medial division of the dorsal nucleus of the raphe, accessory dorsal tegmental nucleus, Kölliker-Fuse nucleus, lateral tegmental field, postpyramidal nucleus of the raphe, pericentral division of the dorsal tegmental nucleus, infratrigeminal nucleus, medial nucleus of the solitary tract, spinal trigeminal tract, dorsal motor nucleus of the vagus, and in the lateral reticular nucleus. According to the distribution of galanin-like immunoreactive structures in the cat brainstem, our data suggest that the peptide could be involved in respiratory, cardiovascular, nociceptive and auditory mechanisms.

Adrenalectomy increases the number of substance P and somatostatin immunoreactive nerve cells in the rat lumbar dorsal root ganglia

Using an immunocytochemical technique we have analyzed changes in substance P, somatostatin, calcitonin gene-related peptide, and galanin immunoreactivity pattern in the rat dorsal root ganglia. After 7 days of adrenalectomy, sham operated rats were compared with adrenalectomized animals either receiving a daily intraperitoneal injection of 10 mg/kg b.wt. corticosterone or vehicle. Three lumbar ganglia from each animal were blocked, serially cut, and immunostained for each neuropeptide by means of the biotin-avidin-peroxidase technique. A systematic sampling of immunoreactive ganglion cells was performed and the sample number of immunoreactive ganglion cells was calculated. After adrenalectomy, the number of substance P and somatostatin immunoreactive ganglion cells markedly increased ((means +/- S.E.M.): 245 +/- 68 versus 123 +/- 12 for sham operated animals, P < 0.01 (substance P) and 42 +/- 8 as compared to 22 +/- 9 for sham operated animals, P < 0.01 (somatostatin)). No significant changes were found in the number of calcitonin gene-related peptide and galanin immunoreactive cells after adrenalectomy. These results suggest that adrenal steroid hormones may reduce the synthesis of both substance P and somatostatin in the dorsal root ganglion cells. Daily treatment with a high dose of corticosterone, mimicking its serum levels after stress, failed to prevent the increase of peptide contents after adrenalectomy. These observations also indicate that a tonic action of corticosterone on mineralocorticoid receptors may be crucial for peptide regulation in the spinal ganglia. These results may be of relevance to adrenalectomy induced changes in sensory mechanisms, neurogenic inflammation and pain transmission and to a role of substance P and somatostatin in these processes.

Distribution of dynorphin A (1-17) in the cat brainstem: an immunocytochemical study

We have studied the distribution of cell bodies and fibers containing dynorphin A (1-17) in the brainstem of the cat using an indirect immunoperoxidase technique. The highest density of cell bodies was observed in the nucleus of the trapezoid body, whereas a low density of perikarya was found in the inferior and superior colliculi, nucleus of the brachium of the inferior colliculus and in the alaminar and laminar spinal trigeminal nuclei. A moderate density of immunoreactive fibers was found in the nucleus of the solitary tract, dorsal nucleus of the raphe, area postrema, dorsal motor nucleus of the vagus and in the marginal nucleus of the brachium conjunctivum, whereas a low density of fibers was observed in the lateral tegmental field, laminar and alaminar spinal trigeminal nuclei, nucleus of the trapezoid body, nucleus coeruleus, brachium conjunctivum, Kölliker-Fuse nucleus, periaqueductal gray and in the inferior and superior colliculi. The highest density of fibers containing dynorphin A was visualized in the substatia nigra. The widespread distribution of dynorphin A (1-17) immunoreactive structures suggests that the peptide could be involved in respiratory, cardiovascular, nociceptive and auditory mechanisms.

Subpopulations of primary sensory neurons show coexistence of neuropeptides and glucocorticoid receptors in the rat spinal and trigeminal ganglia

The coexistence of the neuropeptides substance P, calcitonin gene-related peptide, galanin, somatostatin and neuropeptide Y with glucocorticoid receptors was studied in neurons of the rat lumbar dorsal root and trigeminal ganglia by means of the double immunofluorescence technique. Based on analysis of microphotographs, about one-third of the populations of nerve cells (small and large) containing substance P or calcitonin gene-related peptide immunoreactivity (IR) showed nuclear glucocorticoid receptor IR. A similar pattern was observed within the dorsal root and trigeminal ganglia. Furthermore, within the lumbar dorsal root ganglia 50% of the small neurons, containing galanin IR, possessed nuclear glucocorticoid receptor IR of moderate intensity. Glucocorticoid receptor IR was not observed in the galanin immunoreactive neurons of the trigeminal ganglion neither in the somatostatin and NPY immunoreactive neurons of both the dorsal root and the trigeminal ganglia. The results provide a chemical anatomical basis for a direct regulation by glucocorticoids of distinct populations of substance P and calcitonin gene-related peptide immunoreactive nerve cells in the lumbar spinal and trigeminal ganglia and of galanin immunoreactive nerve cells of the spinal but not of the trigeminal ganglia.

Distribution of gastrin-releasing peptide/bombesin-like immunoreactive cell bodies and fibres in the brainstem of the cat

Using an indirect immunoperoxidase technique, the location of gastrin-releasing/bombesin-like immunoreactive fibres and cell bodies in the cat brainstem was studied. A moderate or low density of immunoreactive cell bodies was observed in the nucleus of the brachium of the inferior colliculus, pericentral nucleus of the inferior colliculus, ventral nucleus of the lateral lemniscus and in the external division of the lateral reticular nucleus. The densest network of immunoreactive fibres was visualized in the interpeduncular nucleus, marginal nucleus of the brachium conjunctivum, alaminar and laminar spinal trigeminal nuclei and in the substantia nigra. The periaqueductal gray, brachium of the inferior colliculus, nucleus of the brachium of the inferior colliculus, locus coeruleus, nucleus incertus, Kölliker-Fuse nucleus, facial nucleus, medial nucleus of the solitary tract and the area postrema contained a moderate density of immunoreactive fibres, whereas the pericentral nucleus of the inferior colliculus, nucleus sagulum, cuneiform nucleus, dorsal nucleus of the raphe, superior central nucleus, central, lateral and paralemniscal tegmental fields, ventral nucleus of the lateral lemniscus, dorsal tegmental nucleus, postpyramidal nucleus of the raphe, nucleus ambiguus, accessory dorsal tegmental nucleus, dorsal motor nucleus of the vagus and the inferior olive had the lowest density of immunoreactive fibres.

Distribution of gastrin-releasing peptide/bombesin-like immunoreactivity in the rainbow trout brain

The distribution of gastrin-releasing peptide (14-27)/bombesin-like immunoreactivity was studied in the brain of the teleost Oncorhynchus mykiss using an indirect immunoperoxidase technique. Cell bodies were only found in the hypothalamic nuclei posterioris periventricularis, the anterior part of the recessus lateralis, and in the recessus posterioris. Immunoreactive fibers were widely distributed in the diencephalon, midbrain, and hindbrain. The highest density of immunoreactive fibers was found in the hypothalamus, whereas a moderate to low density of fibers was visualized in the periventricular thalamus. In the midbrain, a moderate density of fibers was observed at the level of the nuclei lateralis and centralis of the torus semicircularis, the stratum album centrale of the optic tectum, the nucleus of the rostral mesencephalic tegmentum, the nuclei lateralis valvulae, the lemnisci lateralis, istmi and locus coeruleus, as well as in the hindbrain at the level of the nuclei gustatorius secundarius, cerebelli, descendens nervi trigemini, and funiculi lateralis. These data suggest that the peptide could be involved in neuroendocrine (LT, nRL, nRP), visual (OT, nRTM, TS, Is), auditory (TS), and nociceptive (Vd, nufl) mechanisms.

Alpha-neo-endorphin-like immunoreactivity in the cat brain stem

This paper examines the distribution of fibers and cell bodies containing alpha-neo-endorphin in the cat brain stem by using an indirect immunoperoxidase technique. A high or moderate density of immunoreactive cell bodies was found in the superior central nucleus, nucleus incertus, dorsal tegmental nucleus, nucleus of the trapezoid body, and in the laminar spinal trigeminal nucleus, whereas a low density of such perikarya was observed in the inferior colliculus, nucleus praepositus hypoglossi, dorsal nucleus of the raphe, nucleus of the brachium of the inferior colliculus, and in the nucleus of the solitary tract. The highest density of immunoreactive fibers was found in the substantia nigra, dorsal motor nucleus of the vagus, nucleus coeruleus, lateral tegmental field, marginal nucleus of the brachium conjunctivum, and in the inferior and medial vestibular nuclei. These results indicate that alpha-neo-endorphin is widely distributed in the cat brain stem and suggest that the peptide could play an important role in several physiological functions, e.g., those involved in respiratory, cardiovascular, auditory, and motor mechanisms.

Neuropeptide Y in the carp torus semicircularis: an immunocytochemical study

The presence of neuropeptide Y-like immunoreactivity in the torus semicircularis of the teleost fish Cyprinus carpio was studied using an indirect immunoperoxidase technique. In general, both the nuclei lateralis and centralis of the torus semicircularis showed a high density of immunoreactive fibers from rostral to caudal levels. In particular, in the nucleus lateralis a low density of immunoreactive fibers was only found in the subependymal layer, whereas this was high in the small cell, fibrillar and disperse cells layers. Similarly, the nucleus centralis showed a low density of immunoreactive fibers in the fibrillar cortex, and a high density in the cellular region. Moreover, a moderate density of fusiform or round-ovoid cell bodies containing neuropeptide Y-like immunoreactivity was found in the cellular region of the nucleus centralis. These neurons were located dorsally or near to the lateral lemniscus, and situated perpendicular, parallel or oblique to the surface, showing one or two long and relatively unbranching dendritic trunks. The localization of neuropeptide Y-like immunoreactivity in both nuclei--lateralis and centralis--of the carp torus semicircularis suggests that this peptide is involved in the control of visual, auditive, and lateral line mechanisms, as well as in the control of feeding.

Neurokinin A-like immunoreactivity in the cat brainstem

We have studied the distribution of neurokinin A-like immunoreactive cell bodies and fibers in the cat brainstem. The densest clusters of perikarya containing the peptide were observed in the periaqueductal gray, inferior colliculus, postpyramidal nucleus of the raphe, medial nucleus of the solitary tract and in the lateral reticular nucleus. By contrast, the interpeduncular nucleus, magnocellular part of the red nucleus, central tegmental field, cuneiform nucleus, dorsal tegmental nucleus, nucleus sagulum and the medial and inferior vestibular nuclei had the lowest density, whereas a moderate density of immunoreactive cell bodies was found in the superior colliculus, medial division of the dorsal nucleus of the raphe, nucleus incertus, locus coeruleus and in the Kölliker-Fuse area. The highest density of immunoreactive fibers was observed in the substantia nigra, periaqueductal gray, marginal nucleus of the brachium conjunctivum, medial vestibular nucleus, medial nucleus of the solitary tract, laminar spinal trigeminal nucleus, inferior colliculus, medial division of the dorsal nucleus of the raphe, locus coeruleus, dorsal tegmental nucleus and in the spinal trigeminal tract. A moderate density of immunoreactive fibers was found in the dorsal motor nucleus of the vagus and in the postpyramidal nucleus of the raphe and a low density in the cuneiform nucleus, Kölliker-Fuse area, nucleus sagulum, inferior and superior central nuclei, lateral reticular nucleus and in the lateral and magnocellular tegmental fields.

Induction of c-fos immunoreactivity in tyrosine hydroxylase and phenylethanolamine-N-methyltransferase immunoreactive neurons of the medulla oblongata of the rat after phosphate-buffered saline load in the urethane-anaesthetized rat

We have studied the induction of c-fos immunoreactivity (c-fos IR) in catecholaminergic and vasopressinergic immunoreactive neurons after repeated phosphate-buffered saline (PBS) loading or after repeated elicitation of the baroreceptor reflex via repeated infusion of the vasoconstrictor agent L-phenylephrine. About 75% and 30%, respectively, of the tyrosine-hydroxylase immunoreactive (IR) cell bodies of the ventral noradrenaline (NA) A1/adrenaline (A) C1 and dorsal NA A2/A C2 areas and 60% and 30%, respectively, of the phenylethanolamine N-methyltransferase IR nerve cells of the adrenaline C1 and C2 areas and 25% of the vasopressin (VP) IR neurons of the supraoptic (SO) nucleus developed nuclear c-fos IR after repeated PBS loading. This phenomenon remained unaltered by the repeated elicitation of the baroreceptor reflex. These results suggest that the activation of volume receptors promotes homeostatic responses via activation of early genes in subsets of central medullary noradrenaline and adrenaline neurons and SO VP neurons of the urethane-anaesthetized rat.

Coexistence of c-Fos and glucocorticoid receptor immunoreactivities in the CRF immunoreactive neurons of the paraventricular hypothalamic nucleus of the rat after acute immobilization stress

By means of triple immunofluorescence procedures the codistribution and coexistence of glucocorticoid receptor (GR), c-Fos and corticotropin-releasing factor (CRF) immunoreactive (IR) nerve cell profiles have been analyzed within the paraventricular hypothalamic nucleus at various rostrocaudal levels following acute immobilization stress (2 h) in the male rat. One population of CRF IR neurons is shown to contain both nuclear GR and c-Fos immunoreactivities following the stress, while another contains GR immunoreactivity alone. These results indicate heterogeneities among parvocellular CRF paraventricular hypothalamic nerve cell populations in the response to acute immobilization stress.

Distribution of neurokinin A in the cat diencephalon: an immunocytochemical study

The distribution of neurokinin A-like immunoreactive cell bodies and fibers in the diencephalon of the cat was studied using an indirect immunoperoxidase technique. A high or moderate density of immunoreactive neurons was observed in the nuclei habenularis lateralis, medialis dorsalis, parafascicularis, hypothalamus posterior, area hypothalamica dorsalis, hypothalamus lateralis, periventricularis hypothalami, above the corpus mamillare, and in the perifornical area, whereas scarce immunoreactive perikarya were visualized in the nuclei reuniens, hypothalami ventromedialis, hypothalamus dorsomedialis, and mamillaris lateralis. The highest density of fibers containing neurokinin A was found in the nuclei periventricularis anterior, rhomboidens, centralis medialis, periventricularis hypothalami, and supraopticus. In the regio praeoptica, area hypothalamica dorsalis, hypothalamus posterior, and in the perifornical area a moderate density of immunoreactive fibers was observed, whereas the nuclei habenularis lateralis, medialis dorsalis, mamillaris lateralis, parataenialis, reuniens, habenularis medialis, filiformis, hypothalamus dorsomedialis, hypothalami ventromedialis, arcuatus, and suprachiasmaticus showed a low density of neurokinin A immunoreactive fibers.