Galanin is contained in GABAergic neurons in the rat spinal dorsal horn (original) (raw)
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The Journal of Comparative Neurology, 1991
The distribution of galanin-like immunoreactivity (GAL-LI) in the spinal cord of the cat was studied by use of indirect histochemistry and the peroxidase-antiperoxidase (PAP) technique. In the ventral horn GAL-immunoreactive (IR) axonal fibers and terminals were most frequent in the ventral part of the motor nucleus. The GAL-IR axons also contained 5-hydroxytryptamine (5-HT)-LI, and they disappeared after spinal cord transection. It was concluded that these GAL-IR fibers belong to the serotoninergic bulbospinal pathway. In the medulla oblongata from normal cats, scattered GAL-IR cell bodies were encountered within the nucleus raphe obscurus and nucleus raphe pallidus. Electron microscopic observations revealed that the fine structure of the GAL-IR axonal boutons in the motor nucleus was similar to that of 5-HT-IR boutons with a varying number of immunoreactive large dense core vesicles. The postsynaptic element in all cases studied was a dendrite. A dense GAL-IR axonal plexus was found in the superficial laminae 1-11 of the dorsal horn. Coexistence was found between the GAL-and substance P-LI in fibers within the dorsal horn plexus. Spinal cord transection did not alter the pattern of GAL-LI in the dorsal horn, while the vast majority of GAL-IR axonal swellings disappeared following dorsal root sectioning. Electron microscopic observations in lamina I1 (substantia gelatinosa) revealed that the GAL-IR axonal terminals could be divided into two main groups. One with small to medium-sized axonal boutons formed synaptic contacts with both dendritic and axonal profiles. The other formed the central axon terminals of glomeruli, suggesting that GAL-LI may be present in C-type primary afferents. Numerous small GAL-IR cell bodies were encountered in laminae I1 and 111. GAL-IR cell bodies were also observed in lamina X. The dorsal root ganglia contained a low but consistent number of small to medium-sized GAL-IR cell bodies, which all contained immunoreactive calcitonin gene-related peptide (CGRP). Following peripheral sciatic nerve transection, the number and the labeling intensity of GAL-IR cell bodies in the corresponding dorsal root ganglia showed a moderate increase. Radioimmunoassay revealed that the concentration of GAL-LI increased along the rostrocaudal axis of the normal spinal cord, and was about three times higher in the dorsal than in the ventral regions. The concentration in the dorsal root ganglia was intermediate to those seen in the corresponding dorsal and ventral cord regions. Autoradiography showed a
Immunohistochemical mapping of galanin-like neurons in the rat central nervous system
Peptides, 1985
SKOFITSCH, G. AND D. M. JACOBOW1TZ. lntmun<~histochemical mapping of galanin-like neurons in the rat central nervous system. PEPTIDES 6(3) 1985.--Using an antiserum generated in rabbits against synthetic galanin (GA) and the indirect immunofluorescence method, the distribution of GA-like immunoreactive cell bodies and nerve fibers was studied in the rat central nervous sytem (CNS) and a detailed stereotaxic atlas of GA-like neurons was prepared. GA-like immunoreactivity was widely distributed in the rat CNS. Appreciable numbers of GA-positive cell bodies were observed in the rostral cingulate and medial prefrontal cortex, the nucleus interstitialis striae terrninalis, the caudate, medial preoptic, preoptic periventricular, and preoptic suprachiasmatic nuclei, the medial forebrain bundle, the supraoptic, the hypothalamic periventricular, the paraventricular, the arcuate, dorsomedial, perifornical, thalamic periventricular, anterior dorsal and lateral thalamic nuclei, medial and central amygdaloid nuclei, dorsal and ventral premamillary nuclei, at the base of the hypothalamus, in the central gray matter, the hippocampus, the dorsal and caudoventral raphe nuclei, the interpeduncular nucleus, the locus coeruleus, ventral parabrachial, solitarii and commissuralis nuclei, in the A1, C I and A4 catechaolamine areas, the posterior area postrema and the trigeminal and dorsal root ganglia. Fibers were generally seen where cell bodies were observed. Very dense fiber bundles were noted in the septohypothalamic tract, the preoptic area, in the hypothalamus. the habenula and the thalamic periventricular nucleus, in the ventral hippocampus, parts of the reticular formation, in the locus coeruleus, the dorsal parabrachial area, the nucleus and tract of the spinal trigeminal area and the substantia gelatinosa, the superficial layers of the spinal cord and the posterior lobe of the pituitary. The localization of the GA-like immunoreactivity in the locus coeruleus suggests a partial coexistence with catecholaminergic neurons as well as a possible involvement of the GA-like peptide in a neuroregulatory role.
The effect of galanin on wide-dynamic range neuron activity in the spinal dorsal horn of rats
Regulatory Peptides, 2001
. The present study investigated the effect of galanin on wide-dynamic range WDR neuron activity in the dorsal horn of the spinal cord of rats. The evoked discharge of WDR neurons was elicited by transdermic electrical stimulation applied on the ipsilateral hindpaw of rats. Galanin was administered directly on the spinal dorsal surface of L3-L5. The evoked discharge frequency of the WDR neurons decreased significantly after the administration of galanin and the effect lasted for more than 30 min. Furthermore, the inhibitory effect of galanin on the evoked discharge frequency of WDR neurons was blocked by following administration of the galanin antagonist galantide, indicating that the inhibitory effect of galanin on the activity of WDR neurons was induced by activating galanin receptors in the dorsal horn of the spinal cord. The results suggest that galanin has an inhibitory role in the transmission of presumed nociceptive information in the dorsal horn of the spinal cord in rats. q
Neuroscience, 1995
Using light microscopic immunoperoxidase and immunofluorescence histochemistry, doublestaining methodology, and electron microscopic pre-embedding and post-embedding immunocytochemistry, we studied galanin-immunoreactive neurons in the superficial dorsal horn of the rat spinal cord. Co-existence of galanin with other neuropeptides was also analysed. The lumbar 4 and 5 segments of normal rats and after rhizotomy or spinal cord transection were studied. Galanin-positive local neurons in lamina II were often islet cells and could be classified as type A, which had abundant electron-dense cytoplasm containing many large dense-core vesicles, and type B, which had electron-lucent cytoplasm with only a few large dense-core vesicles. Galanin-positive and -negative peripheral afferent terminals made synaptic contact mostly with galanin-negative dendrites and cell bodies, but also with type B galanin cell bodies and with galanin-positive dendrites of unidentified type. Galanin-immunoreactive terminals from local neurons could also be classified into two types. Type ~ terminals were most common; they contained densely packed synaptic vesicles and many large dense-core vesicles, were strongly immunostained and most frequently made synaptic contact with galanin-negative dendrites. Type fl terminals contained loosely packed synaptic vesicles and a few large dense-core vesicles, and were weakly immunostained. Axosomatic synaptic contact were sometimes found betwen type fl terminals and type
Molecular Pain, 2011
Background: Inhibitory interneurons constitute 30-40% of neurons in laminae I-III and have an important antinociceptive role. However, because of the difficulty in classifying them we know little about their organisation. Previous studies have identified 3 non-overlapping groups of inhibitory interneuron, which contain neuropeptide Y (NPY), neuronal nitric oxide synthase (nNOS) or parvalbumin, and have shown that these differ in postsynaptic targets. Some inhibitory interneurons contain galanin and the first aim of this study was to determine whether these form a different population from those containing NPY, nNOS or parvalbumin. We also estimated the proportion of neurons and GABAergic axons that contain galanin in laminae I-III.
Brain Research, 2006
The expression of the galanin receptor-1 and-2 (Gal 1 and Gal 2) messenger ribonucleic acids (mRNAs) was studied in the lower spinal cord of rat by means of in situ hybridization, using ribonucleic acid probes (riboprobes). Naïve rats as well as rats with unilateral axotomy of the sciatic nerve or unilateral inflammation of the hindpaw were analyzed. In naïve rats, numerous Gal 1 mRNA-positive (+) neurons were detected in lamina (L) I-III. In addition, several Gal 1 mRNA + neurons were seen in deeper layers, including the ventral horns, area X, and the lateral spinal nucleus. In contrast, few and comparatively weakly labeled Gal 2 mRNA + neurons were observed, mostly in the ventral horns and in area X, with fewer in the dorsal horn and in the sympathetic and parasympathetic intermediate lateral cell columns. Axotomy induced a strong increase in intensity and number of Gal 2 mRNA + motoneurons ipsilateral to the lesion. In contrast, nerve cut or hindpaw inflammation did not alter the expression of Gal 1 or Gal 2 in the dorsal horn. The present (and previous) results suggest that galanin, acting through Gal 1 and Gal 2 receptors, has a modulatory role on spinal excitability, not only via interneurons in superficial dorsal horn, but also on neurons in deep layers and area X, as well as on the sympathetic and parasympathetic outflow. Furthermore, the nerve injury-induced Gal 2 upregulation in motor neurons suggests a role for galanin in survival/ regeneration mechanisms.
Journal of Neurocytology, 1993
Using the indirect immunofluorescence method and in situ hybridization, the localization and levels of immunoreactivities and mRNAs for several neuropeptides were studied in lumbar dorsal root ganglia and spinal cord of untreated monkeys (Macaca mulatta) and after unilateral transection of the sciatic nerve. Immunoreactive galanin, calcitonin gene-related peptide, substance P and somatostatin and their mRNAs were found in cell bodies in dorsal root ganglia of untreated monkeys and on the contralateral side of the monkeys with unilateral sciatic nerve lesion. After axotomy there was a marked decrease in the number of calcitonin gene-related peptide-, substance P-and somatostatin-positive neurons in dorsal root ganglia ipsilateral to the lesion, whereas the number of galanin positive cells strongly increased. A few neuropeptide tyrosine-positive cells were seen in after axotomy, whereas no such neurons were found in controls. No vasoactive intestinal polypeptide-, peptide histidine isoleucine-, cholecystokinin-, dynorphin-, enkephalin-, neurotensin-or thyrotrophin releasing hormone-positive cell bodies were seen in dorsal root ganglia of any of the groups studied. In the dorsal horn of the spinal cord all peptide immunoreactivities described above, except thyrotropin releasing hormone, were found in varying numbers of nerve fibres with a similar distribution in untreated monkeys and in the contralateral dorsal horn in monkey with unilateral sciatic nerve lesion. Two cholecystokinin antisera were used directed against the C-and N-terminal portions, respectively, showing a distinctly different distribution pattern in the dorsal horn. Somatostatin-and dynorphin-like immunoreactivities were also observed in small neurons in the dorsal horn. No certain effect of axotomy on these interneurons could be seen. However, marked changes were observed after this type of lesion for some peptide containing fibres in the ipsilateral dorsal horn. Thus, there was a marked increase in galanin-like immunoreactivity, whereas calcitonin gene-related peptide-, substance P-, somatostatin-, peptide histidine isoleucine neurotensin-and cholecystokinin-like immunoreactivities decreased. No changes could be observed in neuropeptide tyrosine or enkephalin-positive fibres. The present results demonstrate marked ganglionic and transganglionic changes in peptide levels after peripheral axotomy. When compared to published results on the effect of axotomy on peptides in dorsal root ganglia and spinal cord of rat, both similarities and differences were encountered. Thus, in contrast to rat there was no marked upregulation of vasoactive intestinal polypeptide/peptide histidine isoleucine or neuropeptide tyrosine after axotomy in the monkey, whereas galanin was increased in both species. Both in monkey and rat, calcitonin gene-related peptide, substance P and somatostatin decreased. The decrease in neurotensin, peptide histidine isoleucine, and 'genuine' cholecystokinin seen in monkey after axotomy has not been reported in the rat. Experimental studies on rat suggest that galanin may be an endogenous analgesic compound, active particularly after peripheral nerve lesions. We have therefore recently proposed that galanin agonists may be used in treatment of chronic pain, and the present demonstration that galanin is regulated in a similar fashion in a primate gives further support to the proposal to test galanin as an analgesic in human.
The effect of galanin on WDR neuron activity in the spinal dorsal horn of rats 2001.pdf
. The present study investigated the effect of galanin on wide-dynamic range WDR neuron activity in the dorsal horn of the spinal cord of rats. The evoked discharge of WDR neurons was elicited by transdermic electrical stimulation applied on the ipsilateral hindpaw of rats. Galanin was administered directly on the spinal dorsal surface of L3-L5. The evoked discharge frequency of the WDR neurons decreased significantly after the administration of galanin and the effect lasted for more than 30 min. Furthermore, the inhibitory effect of galanin on the evoked discharge frequency of WDR neurons was blocked by following administration of the galanin antagonist galantide, indicating that the inhibitory effect of galanin on the activity of WDR neurons was induced by activating galanin receptors in the dorsal horn of the spinal cord. The results suggest that galanin has an inhibitory role in the transmission of presumed nociceptive information in the dorsal horn of the spinal cord in rats. q
Regulatory peptides, 2000
Galanin is a 29-amino acid peptide with a suggested role in nociception. The effect of galanin on wide-dynamic range neuron discharge frequency in rats with nerve ligation, used as a model of neurogenic pain, was investigated by extracellular recording methods. Seven to 14 days after sciatic nerve ligation, 0.1, 0.5 or 1 nmol of galanin was administered directly on the dorsal surface of the L3-L5 spinal cord of rats with sciatic nerve ligation. It was found that galanin inhibited the activity of wide-dynamic range neurons dose-dependently, an effect was more pronounced in sciatic nerve ligated rats than intact rats. Furthermore, when 1 nmol of galantide, the galanin antagonist, was administered on the dorsal surface of the L3-L5 spinal cord, the wide-dynamic range neuron discharge frequency increased significantly. The results suggest that galanin plays an important role in the modulation of presumed nociception in mononeuropathy.