Substance P-like Immunoreactive Cells Research Articles

Activity-Dependent Regulation of Substance P Expression and Topographic Map Maintenance by a Cholinergic Pathway

We have assessed the role of activity in the adult frog visual system in modulating two aspects of neuronal plasticity: neurotransmitter expression and topographic map maintenance. Chronic treatment of one tectal lobe with the non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione decreased the percentage of substance P-like immunoreactive (SP-IR) tectal cells in the untreated lobe while disrupting topographic map formation in the treated one. Treatment with the NMDA receptor antagonist d-(-)-2-amino-5-phosphonovaleric acid (d-AP-5) disrupted the topographic map but had no affect on SP-IR cells. These results indicate that maintenance of the topographic map is dependent on direct input from the glutamatergic retinal ganglion cells, whereas substance P (SP) expression is being regulated by a pathway that relays activity from one tectal lobe to the other. Such a pathway is provided by the cholinergic nucleus isthmi, which is reciprocally connected to the ipsilateral tectum and sends a projection to the contralateral one. Mecamylamine and atropine, antagonists of nicotinic and muscarinic receptors, respectively, were used together to block all cholinergic activity or alone to block receptor subclass activity. All three treatments decreased SP expression and disrupted the topographic map in the treated tectal lobe. We conclude that both SP expression and topographic map maintenance in the adult optic tectum are activity-dependent processes. Although our results are consistent with the maintenance of the topographic map through an NMDA receptor-based mechanism, they suggest that SP expression is regulated by a cholinergic interaction that depends on retinal ganglion cell input only for its activation.

Distribution of substance P-like immunoreactivity in guinea pig central nervous system

The distribution of substance P-like immunoreactivity (SP-LI) in the guinea pig brain has been studied by immunohistochemistry and the results compared with the distribution in similar regions in the rat brain. In both species, dense SP-LI staining was found in the median eminence, arcuate hypothalamic nucleus, substantia nigra, dorsal raphe and dorsal tegmental nuclei, nucleus of the solitary tract, substantia gelatinosa of the spinal trigeminal nucleus, and spinal cord. Less dense staining was found in the caudate putamen, globus pallidus, nucleus accumbens, habenula, hypothalamic areas, and central grey. SP-LI cell bodies were found in areas previously described for the rat brain including several hypothalamic areas, limbic areas, central grey, and dorsal raphe and solitary tract nuclei. The major difference between the two species was found in the cortex and hippocampus. The guinea pig cortex contained many more SP-LI cells and fibres, distributed in layers II–VI, than the rat cortex. The guinea pig hippocampus contained marked staining, particularly in the pyramidal cell layer of CA1–3 fields of Ammon's horn and in the granular layer of the dentate gyrus. and SP-LI cells in the hilus of the dentate gyrus, whereas rat hippocampus contained few cells and no regions of dense staining. It is concluded that because the guinea pig brain has an extensive distribution of SP-LI in the cortex and hippocampus it resembles the primate brain more closely than does the rat brain.

Substance-P-like immunoreactive amacrine cells in the adult and the developing rat retina

Substance-P-like immunoreactivity (SP-LI) cells in the Long-Evans rat retina were investigated by combining immunohistochemistry with [ 3H]thymidine autoradiography. Two subpopulations of SP-LI amacrine cells, with cell bodies in either the proximal portion of the inner nuclear layer (INL) or the ganglion cell layer (GCL), were identified based on morphology, pattern of distribution and development. In the INL, SP-LI cells were found scattered throughout the retina. However, in the GCL, they were limited to the superior-temporal region. Such a contrast in distribution specific to nuclear layers was present upon first detection of SP-LI amacrine cells and persisted throughout development. Birthdating revealed a temporal lag in the histogenesis of SP-LI cells situated in the GCL relative to that in the INL, suggesting that the two subpopulations developed separately. Overall, unique anatomical features of the SP-LI amacrine cells in the rat retina were observed which could only have been uncovered through detailed analyses in the adult as well as during postnatal development.

The morphology and topographic distribution of substance- P-like immunoreactive amacrine cells in the cat retina

In cat retinal wholemounts, substance-P-like immunoreactivity (SP-IR) was localized in a distinct population of amacrines whose cell bodies were normally placed in the ganglion cell layer. Although displaced amacrines accounted for 80-95% of the SP-IR amacrines in peripheral retina, this proportion decreased considerably within the area centralis, accounting for 50-80% of the labelled cells at maximum density. The SP-IR cells in both the inner nuclear and ganglion cell layers gave rise to well-defined varicose dendrites of uniform appearance that stratified around 60% depth (S3/S4) of the inner plexiform layer. In addition, sparse fine dendrites in stratum 1 (S1) could sometimes be traced to inner nuclear cells and occasionally to displaced amacrines. The combined SP-IR cell density ranged from less than 50 cells mm-2 in the far periphery to more than 500 cells mm-2 in the area centralis; the maximum density showed little individual variation despite wide differences in the proportion of displaced cells. The 39,000 SP-IR amacrines in a mapped retina had a triangular topographic distribution, with intermediate isodensity lines extending vertically in superior retina and horizontally along both arms of the visual streak. Colocalization experiments established that all SP-IR cells in cat retina showed GABA-like immunoreactivity, and that the SP-IR amacrines were quite distinct from the cholinergic amacrines identified by choline acetyltransferase immunohistochemistry.

The colocalization of substance P- and somatostatin-like peptides in neurons of the entopeduncular nucleus of rats

The colocalization of substance P-like and somatostatin-like immunoreactivity in cell bodies was investigated in the entopeduncular nucleus of rats by a double immunofluorescence method using species specific antibodies. Most of the substance P-like immunoreactive cells were also positive to somatostatin and mainly seen in the rostral to middle region of the entopeduncular nucleus. Therefore it is suggested that double-labeled neurons in the entopeduncular nucleus project to the lateral habenular nucleus which is involved in the limbic system, since the rostral portion of the entopeduncular nucleus has been shown to project to the lateral habenular nucleus.

The coexistence of substance P- and glutamic acid decarboxylase-like immunoreactivity in entopeduncular neurons of the rat

The coexistence of substance P- and glutamic acid decarboxylase-like immunoreactivity in cell bodies was investigated in the entopeduncular neurons of the rat by the double-immunofluorescence method using species-specific antibodies. Over half of the substance P-like immunoreactive cells were GABAergic. Double-labeled neurons were generally seen in the rostral to the middle region of the entopeduncular nucleus. Since the rostral portion of the entopeduncular nucleus mainly projects to the lateral habenular nucleus, it is suggested that double-labeled neurons in the entopeduncular nucleus largely project to the lateral habenular nucleus which is involved in the limbic system.

Morphological characterization of substance P-like immunoreactive amacrine cells in the anuran retina

Using substance P immunohistochemistry it was possible to demonstrate a class of morphologically homogeneous group of neurons in the inner nuclear layer (INL) of the retina of two anuran species: Xenopus laevis and Bufo marinus. The number of cells with substance P-like immunoreactivity (SP-LI) was about 250 and 800 in juvenile and 600 and 2500 in adult Xenopus and Bufo, respectively. SP-LI cells had a small soma with one primary dendrite having up to four slender branches, located in the vitreal sublamina of the inner plexiform layer (IPL). Mean dendritic field sizes were 0.12 and 0.30 mm 2 in juvenile and 0.29 and 0.65 mm 2 in adult Xenopus and Bufo, respectively. The density of SP-LI cells was 40/mm 2 in juvenile and 24/mm 2 in adult Xenopus compared with 20/mm 2 in juvenile and 13/mm 2 in adult Bufo. Nearest neighbour distance measurements indicated that SP-LI cells were randomly distributed across the entire retina in both species. The location and the morphology of SP-LI cells indicated that they correspond to a subclass of wide-field amacrine cells, similar to types 20 and 21 described by Golgi techniques in the cat.

Distribution of substance P‐like immunoreactive retinal ganglion cells and their pattern of termination in the optic tectum of chick (Gallus gallus)

Substance P-like immunoreactive (SP-LI) neurons were identified within the inner nuclear layer and ganglion cell layer of the chick retina. The SP-LI cells in the inner nuclear layer consisted of several subtypes of neurons, differing in soma size and dendritic arborization. In the ganglion cell layer a population of moderately labelled SP-LI neurons was also present. About 6-9 microns in diameter and spaced 50-80 microns apart, they formed a regular array across the entire retina, with a density of about 400 cells/mm2 in the superior temporal retina, declining to less than 100 cells/mm2 in the peripheral retina. The total number of SP-LI cells in the ganglion cell layer was approximately 75,000. Individual axons could be followed toward the optic nerve head. Lesions near the optic nerve head resulted in axotomy of ganglion cells within a limited portion of the retina. Two days of postaxotomy there were numerous SP-LI swellings in the proximal segments of axotomized axons. SP-LI neurons in the axotomized zone were larger, more numerous, and showed increased staining of their processes. Fourteen days following a retinal lesion, there was depletion of all SP-LI cells in the ganglion cell layer within the axotomized zone, but the SP-LI neurons in the inner nuclear layer were not noticeably affected. Following a localized injection of rhodamine-coupled latex beads into the optic tectum, a population of retinal ganglion cells (RGCs) in the contralateral retina was retrogradely labelled. Many of these cells also exhibited SP-like immunoreactivity. Examination of the optic tectum indicated the presence of SP-LI fibres in laminae 2-13 (nomenclature of Cajal: Histologie du Systeme Nerveux. Vol. 2. Paris: Maloine, '11), with immunoreactive terminal regions present mainly in laminae 2-4, 7, and 9-13. SP-LI cell bodies were found predominantly in laminae 10-12 and 13. Fourteen days following a retinal lesion, SP-LI processes and terminals were depleted from laminae 2 and 3. Immunoreactive cells and processes in the remaining laminae of the optic tectum were not noticeably altered. The present report confirms the existence of SP-LI retinal ganglion cells in the chick retina and demonstrates their contribution to lamina specific SP-LI arborization in the optic tectum.

Substance P-immunoreactive retinal ganglion cells and their central axon terminals in the rabbit

Retinal ganglion cells are the projection neurons that link the retina to the brain. Peptide immunoreactive cells in the ganglion cell layer (GCL) of the mammalian retina have been noted but their identity has not been determined. We now report that, in the rabbit, 25-35% of all retinal ganglion cells contain substance P-like (SP) immunoreactivity. They were identified by either retrograde transport of fluorescent tracers injected into the superior colliculus, or by retrograde degeneration after optic nerve section. SP immunoreactive cells are present in all parts of the retina and have medium to large cell bodies with dendrites that ramify extensively in the proximal inner plexiform layer. Their axons terminate in the dorsal lateral geniculate nucleus, superior colliculus and accessory optic nuclei, and these terminals disappear completely after contralateral optic nerve section and/or eye enucleation. In the dorsal lateral geniculate nucleus large, beaded, immunoreactive axons and varicosities make up a narrow plexus just below the optic tract, where they define a new geniculate lamina. The varicosities make multiple synaptic contacts with dendrites of dorsal lateral geniculate nucleus projection neurons and presumptive interneurons in complex glomerular neuropil. This is direct evidence that some mammalian retinal ganglion cells contain substance P-like peptides and strongly suggests that, in the rabbit, substance P (or related tachykinins) may be a transmitter or modulator in a specific population or populations of retinal ganglion cells.

Distribution of some peptides (substance P, [Leu]enkephalin, [Met]enkephalin) in the brain stem and spinal cord of a lizard, Varanus exanthematicus

The distribution of substance P-like and [Leu]- and [Met]enkephalin-immunoreactive cell bodies, fibers and terminal structures in the brain stem and spinal cord of a lizard, Varanus exanthematicus, was studied with the indirect immunofluorescence technique, using antibodies to these peptides. Substance P-like immunoreactive cell bodies were found in the hypothalamus, in a periventricular cell group in the rostral mesencephalon, in the interpeduncular nucleus, in and ventral to the descending nucleus of the trigeminal nerve, in and directly ventral to the nucleus of the solitary tract, scattered in the brain stem reticular formation and in the trigeminal and spinal ganglia. A rather widespread distribution of substance P-like immunoreactivity was found in the brain stem and spinal cord, mainly concentrated in striatotegmental projections, in projections related to visceral and/or taste information (nucleus of the solitary tract, parabrachial region), in the descending nucleus of the trigeminal nerve and in the dorsal horn of the spinal cord (areas I and II). In the spinal cord also around the central canal (area X and adjacent parts of area V–VI) a distinct substance P innervation was found. The ventral horn receives only a very sparse substance P innervation. The distribution of [Leu]- and [Met]enkephalin in the brain stem and spinal cord of Varanus exanthematicus is less impressive than that of substance P. Enkephalinergic cell bodies were found particularly in the caudal hypothalamus. Small populations of enkephalinergic cell bodies were found in the vestibular nuclear complex, in the nucleus of the solitary tract, in and around the descending nucleus of the trigeminal nerve and throughout the rhombencephalic reticular formation. Enkephalins are likely to be present in efferent projections of the striatum, in projections related to taste and/or visceral information (nucleus of the solitary tract, parabrachial region) and in descending pathways to the spinal cord. Enkephalinergic fibers are present in the lateral funiculus and enkephalin-immunoreactive cell bodies are found in the reticular formation, particularly the inferior reticular nucleus which is known to project to the spinal cord. In the spinal cord enkephalinergic terminal structures were found especially in the superficial layer of the dorsal horn (areas I and II) and around the central canal. The ventral horn including the motoneuron area receives only a relatively sparse enkephalinergic innervation.

Growth of central substance P-containing neurons into superior cervical ganglia transplanted in the spinal cord of adult rats

Superior cervical ganglia (SCG) contain substance P-like immunoreactive (SP-IR) fibers but not SP-IR neurons. In the present study, SCG were excised from adult rats and transplanted into the same animal's spinal thoracic cord (Th10). One or two weeks after the operation, SP-IR fibers from the host spinal cord or a higher level had grown and entered the transplanted SCG where they formed direct contacts with SCG neurons. However, these phenomena could not be observed when dorsal root ganglia (L4), which contained numerous SP-IR cells, were transplanted into their own spinal cord (Th10). This suggests that the SP-IR neuron system in the adult is able to grow ‘new axons’ to the grafted tissue to form a ‘new SP-IR’ neuronal circuit when the grafted tissue has lost its own SP-IR input.

Substance P neuronal organization in the median region of the interpeduncular nucleus of the cat: An electron microscopic analysis

The localization of substance P-like immunoreactivity in the interpeduncular nucleus using the peroxidase-antiperoxidase technique, revealed that the median region of the interpeduncular nucleus was one area rich in substance P-like immunoreactive processes. The ultrastructural characteristics of these substance P-like immunoreactive processes and their organization within the middle zone of the median region of the interpeduncular nucleus was studied. Substance P-like immunoreactivity was found in the perikaryon of small neurons, and in proximal and small dendrites. The substance P-like immunoreactive cell bodies and proximal dendrites receive a variety of unlabeled synaptic terminals. The immunoreactive small dendrites usually formed the central component of a “rosette” like formation with unlabeled terminals. A few immunoreactive small unmyelinated axons and boutons were also present in the neuropil. The substance P-like immunoreactive boutons contained mainly small round vesicles with some large dense-core vesicles. These substance P-like immunoreactive boutons were presynaptic to unlabeled dendritic profiles, and frequently to substance P-like immunoreactive dendritic profiles. They were also seen in apposition to unlabeled boutons. Substance P-like immunoreactive boutons were not found to synapse with the crest-like dendritic processes in this part of the interpeduncular nucleus. It is suggested on the basis of morphological features, that some of the unlabeled terminals synapsing on substance P-like immunoreactive dendrities, may be cholinergic in nature.

The immunohistochemical localization of nine peptides in the sacral parasympathetic nucleus and the dorsal gray commissure in rat spinal cord

The sixth lumbar and first sacral spinal cord segments in the rat contain parasympathetic preganglionic neurons which innervate the pelvic viscera. There have been few studies, however, which have specifically considered the distribution of putative peptide neurotransmitters in these cord segments. The present paper describes and compares the immunohistochemical distribution of dynorphin (1–8)-,enkephalin-, somatostatin-, cholecystokinin octapeptide-, avian pancreatic polypeptide-, FMRF-NH 2-,neurotensin-, and vasoactive intestinal polypeptide-like immunoreactivities in the dorsal gray commissure and sacral parasympathetic nucleus of the sixth lumbar and first sacral spinal cord segments in colchicine-treated rats. Antisera against all of the peptides, except avian pancreatic polypeptide, stained cells in the sacral parasympathetic nucleus. Dynorphin (1–8-), enkephalin-, and substance P-like immunoreactive cells were present in significantly greater numbers than somatostatin-, neurotensin-, cholecystokinin-, FMRF-NH 2-,and vasoactive intestinal polypeptide-like immunoreactive cells. All of the antisera also stained fibers in the sacral parasympathetic nucleus in varying densities, and a fiber bundle which extended between the dorsal gray commissure and the sacral parasympathetic nucleus. Antisera against substance P and cholecystokinin stained a bundle of fibers that extended between the dorsal horn and the sacral parasympathetic nucleus. Antisera against somatostatin, cholecystokinin octapeptide, substance P and FMRF-NH 2 stained an additional fiber bundle which extended between the lateral edge of the dorsal horn and the dorsal gray commissure. All the remaining antisera, except neurotensin, also stained fibers that extended between the sacral parasympathetic nucleus and the dorsal gray commissure, but in a sparser distribution. Immunoreactive cells were localized to the dorsal gray commissure in sections stained with each of the antisera. Dynorphin (1–8) and enkephalin antisera stained the greatest number of cells, followed by FMRF-NH 2, neurotensin, somatostatin and avian pancreatic polypeptide. The smallest number of immunoreactive cells was present in substance P, cholecystokinin and vasoactive intestinal polypeptide immunostained sections. A significant difference was noted between the number of dynorphin, enkephalin, somatostatin, cholecystokinin, avian pancreatic polypeptide, FMRF-NH 2, neurotensin and vasoactive intestinal polypeptide immunoreactive cells in the sacral parasympathetic nucleus and dorsal gray commissure. Plexuses of immunostained fibers were also present in varying densities in the dorsal and ventral portions of the dorsal gray commissure of sections stained with each of the antisera. All of the peptides except vasoactive intestinal polypeptide were also localized to a longitudinal bundle of fibers just dorsal to the central canal. The neurotensin-like immunoreactive fiber bundle was less dense than fibers stained with the other antisera and only present in the first sacral segment. A longitudinal fiber bundle ventral to the central canal was identified in sections immunostained with all of the antisera except neurotensin. Immunostained fibers located along the lateral edge of the dorsal funiculus and extending between the dorsal horn and dorsal gray commissure were seen in sections stained with all of the antisera. It is not clear what function is mediated by the putative peptide neurotransmitters located in these immunostained cells and fibers, however, their close association with autonomic structures in these levels suggests that they may be intimately involved in the parasympathetic regulation of pelvic viscera.

Substance P-immunoreactive and serotonin-containing neurones in the ventral brainstem of the cat

Substance P-like immunoreactive cell bodies have been described in the cat brainstem after local injections of colchicine. Substance P-containing neurones were found in the nucleus raphe pallidus, the nucleus raphe obscurus and at the caudal end of the nucleus raphe magnus. Two groups of substance P-positive (+) cells were also found in the ventrolateral medulla. Small substance P + cells were present in a narrow band immediately ventral to the facial nucleus, and a second group of small and medium sized neurones was found in a strip ventrolateral to the rostral half of the inferior olive. Some of these cells lay in close proximity to the ventral surface of the brain. Double labelling studies indicated that within the raphe nuclei many substance P + neurones also contained serotonin, while within ventrolateral areas of the medulla, the most rostral cell group stained only for substance P and the more caudal nucleus for both substance P and serotonin.

Origins of substance P-containing fibers in the lateral septal area of young rats: immunohistochemical analysis of experimental manipulations.

The majority of substance P-like immunoreactive (SPLI) fibers in the lateral septal area (LS) are supplied by SPLI cells in the area (BAL) between the anterior hypothalamic nucleus and the lateral hypothalamus, and by those in the nucleus latero-dorsalis tegmenti (TLD). These conclusions are based on following: (1) Unilateral destruction of the BAL resulted in an ipsilateral decrease in the septal SPLI fibers similar to that seen after the destruction of the TLD, and (2) simultaneous destruction of the BAL and TLD caused a marked reduction of SPLI fibers in the LS on the operated side. The possibility that the destruction of the BAL affected the ascending SPLI system from the TLD seems to be excluded, because (1) the destruction of the TLD resulted in a decrease in SPLI fibers in the ipsilateral medial forebrain bundle (MFB), but failed to reduce the number of SPLI fibers in the BAL, and (2) the destruction of the BAL caused a decrease in SPLI fibers in the perifornical area rostral to the lesion, but failed to reduce the number of SPLI fibers in the MFB. These facts further suggest that ascending SPLI fibers from the BAL travel in the perifornical area and those from the TLD pass through the MFB. It should be noted that a few SPLI fibers remained intact following the simultaneous destruction of the BAL and TLD. The present study suggests that these remaining SPLI fibers might be innervated by intrinsic SPLI cells. In support of this, several SPLI cells were detected in the septal area after colchicine pretreatment.