Biomedical subjects

A C Cuello

Publications and source records attributed to A C Cuello.

At least 19 recordsLinked to original sources

PubMed2001

Light and electron microscopic study of the distribution of substance P-immunoreactive fibers and neurokinin-1 receptors in the skin of the rat lower lip.

Cutaneous antidromic vasodilatation and plasma extravasation, two phenomena that occur in neurogenic inflammation, are partially blocked by substance P (SP) receptor antagonists and are known to be mediated in part by mast cell-released substances, such as histamine, serotonin, and nitric oxide. In an attempt to provide a morphological substrate for the above phenomena, we applied light and electron microscopic immunocytochemistry to investigate the pattern of SP innervation of blood vessels and its relationship to mast cells in the skin of the rat lower lip. Furthermore, we examined the distribution of SP (neurokinin-1) receptors and their relationship to SP-immunoreactive (IR) fibers. Our results confirmed that SP-IR fibers are found in cutaneous nerves and that terminal branches are observed around blood vessels and penetrating the epidermis. SP-IR fibers also innervated hair follicles and sebaceous glands. At the ultrastructural level, SP-IR varicosities were observed adjacent to arterioles, capillaries, venules, and mast cells. The varicosities possessed both dense core vesicles and agranular synaptic vesicles. We quantified the distance between SP-IR varicosities and blood vessel endothelial cells. SP-IR terminals were located within 0.23-5.99 microm from the endothelial cell layer in 82.7% of arterioles, in 90.2% of capillaries, and in 86.9% of venules. Although there was a trend for SP-IR fibers to be located closer to the endothelium of venules, this difference was not significant. Neurokinin-1 receptor (NK-1r) immunoreactivity was most abundant in the upper dermis and was associated with the wall of blood vessels. NK-1r were located in equal amounts on the walls of arterioles, capillaries, and venules that were innervated by SP-IR fibers. The present results favor the concept of a participation of SP in cutaneous neurogenic vasodilatation and plasma extravasation both by an action on blood vessels after binding to the NK-1r and by causing the release of substances from mast cells after diffusion through the connective tissue.

Animals↗

PubMed2001

Cholinergic nerve terminals establish classical synapses in the rat cerebral cortex: synaptic pattern and age-related atrophy.

This study addresses the issue of whether cholinergic varicosities in the cerebral cortex establish 'classical synapses' or whether they communicate with their targets non-synaptically by 'volume transmission'. Most recent studies in the neocortex have suggested that acetylcholine acts non-synaptically, however in the present study we provide ultrastructural evidence that suggests synaptic mechanisms prevail. This conclusion is based upon our ultrastructural observations that cholinergic boutons--as revealed by immunoreactivity for the specific cholinergic market, vesicular acetylcholine transporter--establish a high percentage of classical synapses in layer V of the rat parietal cortex. Furthermore, the combination of this approach with the intracellular labeling of large pyramidal neurons on slice preparations revealed significant incidences of cholinergic contacts abutting preferentially on dendritic shafts. Finally, we have gathered information suggesting that cholinergic boutons undergo atrophy with aging which could be related to the well-known cholinergic and cognitive decline. These results illustrate that the cholinergic terminations in the neocortex establish proper synaptic connections and that they experience important age-dependent atrophy.

Acetylcholine↗

PubMed2000

Loss of presynaptic and postsynaptic structures is accompanied by compensatory increase in action potential-dependent synaptic input to layer V neocortical pyramidal neurons in aged rats.

Reduction in both presynaptic and postsynaptic structures in the aging neocortex may significantly affect functional synaptic properties in this area. To directly address this issue, we combined whole-cell patch-clamp recording of spontaneously occurring postsynaptic currents (PSCs) with morphological analysis of layer V pyramidal neurons in the parietal cortex of young adult (1- to 2-month-old) and aged (28- to 37-month-old) BN x F344 F(1) hybrid rats. Analysis of spontaneous PSCs was used to contrast functional properties of basal synaptic input with structural alterations in the dendritic tree of pyramidal neurons and density of terminals in contact with these cells. We observed significant changes in a number of morphological parameters of pyramidal neurons in aged rats. These include smaller cell body size and fewer basal dendritic branches (but not of oblique dendrites and dendritic tufts) and spines. Ultrastructural analysis also revealed a lower density of presynaptic terminals per unit length of postsynaptic membrane of labeled pyramidal neurons in the aged brain. This reduction in both presynaptic and postsynaptic elements was paralleled by a significant decrease in frequency of tetrodotoxin-insensitive miniature (action potential-independent) PSCs (mPSCs). The frequency of excitatory and inhibitory mPSCs was reduced to the same extent. In contrast, no significant change was observed in the frequency of spontaneous PSCs recorded in absence of tetrodotoxin (sPSCs), indicating an increase in action potential-dependent (frequency(sPSCs) - frequency(mPSCs)) input to pyramidal neurons in the aged group. This functional compensation may explain the lack of drastic loss of spontaneous neuronal activity in normal aging.

Action Potentials↗

PubMed2000

Peripheral nerve injury leads to the establishment of a novel pattern of sympathetic fibre innervation in the rat skin.

Peripheral nerve injury has been shown to result in sympathetic fibre sprouting around dorsal root ganglia (DRG) neurons. It has been suggested that this anomalous sympathetic fibre innervation of the DRG plays a role in neuropathic pain. Other studies have suggested an interaction between sympathetic and sensory fibres more peripherally. To date, no anatomical study of these possible interactions in the terminal fields of sensory and sympathetic fibres has been performed; therefore, the authors set out to study them in the rat lower lip after bilateral lesions of a sensory nerve, the mental nerve (MN). Immunocytochemistry for both substance P (SP) and dopamine-beta-hydroxylase (DbetaH) was performed. Within the first week post-MN lesions, the SP-immunoreactive (IR) fibres had degenerated almost completely, whereas DbetaH-IR fibres were found in the upper dermis, an area from which they normally are absent. These DbetaH-IR fibres were present in the upper dermis at all postsurgery times studied (1, 2, 3, 4, 6, and 8 weeks). It is noteworthy that, although, by week 6 post-MN lesions, SP-IR fibre reinnervation of the lower lip was occurring, the DbetaH-IR fibres still were present in the upper dermis. Quantification revealed that the migration and branching of the DbetaH-IR fibres into the upper dermis occurred gradually and was most significant at 4 weeks post-MN lesions, as demonstrated by the fact that the DbetaH-IR fibres were found 169.6 +/- 91.4 microm away from the surface of the skin compared with 407.1 +/- 78.4 microm away in sham-operated animals. These findings suggest that the ectopic innervation of the upper dermis by sympathetic fibres may be important in the genesis of neuropathic pain through the interactions of sympathetic and SP-containing sensory fibres.

Animals↗

PubMed2000

Genuine monovalent ligands of TrkA nerve growth factor receptors reveal a novel pharmacological mechanism of action.

Developing small molecule agonistic ligands for tyrosine kinase receptors has been difficult, and it is generally thought that such ligands require bivalency. Moreover, multisubunit receptors are difficult to target, because each subunit contributes to ligand affinity, and each subunit may have distinct and sometimes opposing functions. Here, the nerve growth factor receptor subunits p75 and the tyrosine kinase TrkA were studied using artificial ligands that bind specifically to their extracellular domain. Bivalent TrkA ligands afford robust signals. However, genuine monomeric and monovalent TrkA ligands afford partial agonism, activate the tyrosine kinase activity, cause receptor internalization, and induce survival and differentiation in cell lines and primary neurons. Monomeric and monovalent TrkA ligands can synergize with ligands that bind the p75 subunit. However, the p75 ligands used in this study must be bivalent, and monovalent p75 ligands have no effect. These findings will be useful in designing and developing screens of small molecules selective for tyrosine kinase receptors and indicate that strategies for designing agonists of multisubunit receptors require consideration of the role of each subunit. Last, the strategy of using anti-receptor mAbs and small molecule hormone mimics as receptor ligands could be applied to the study of many other heteromeric cell surface receptors.

Amino Acid Sequence↗

PubMed2000

Upregulation of an opioid-mediated antinociceptive mechanism in transgenic mice over-expressing substance P in the spinal cord.

In transgenic mice expressing ectopic substance P fibres in the spinal white matter, a normally innocuous mechanical stimulus induces hyperalgesia and allodynia which are reversed by substance P and N-methyl-D-aspartate receptor antagonists. This period of enhanced excitation is followed by a rebound overshoot in these animals. As previous evidence indicates opioid mechanisms in a similar rebound in normal animals, the present study was done to determine the effects of systemic administration of morphine and the opiate receptor antagonist, naloxone, on the stimulus-induced responses in the tail withdrawal reflex. Once baseline reaction times had been taken, different combinations of saline, naloxone and morphine were administered intraperitoneally to transgenic and control mice of either sex. A mechanical conditioning stimulus of 450g was then applied to the tip of the tail for 2s. This stimulus was innocuous in control mice given saline or naloxone, but provoked a nociceptive response in transgenic mice given these compounds. In control and transgenic mice, following morphine administration there was an antinociceptive effect. In control mice the subsequent mechanical stimulus had no effect. However, in transgenic mice the mechanical stimulus produced a further antinociception. Naloxone blocked the effect of morphine and the subsequent conditioning stimulus in both control and transgenic mice. The results indicate that while morphine is equally effective on the withdrawal reflex in both types of animal, in the transgenic mice morphine reveals an intrinsic, naloxone-sensitive antinociceptive mechanism. The data are interpreted to suggest that over-expression of substance P or some other factor in the spinal cord of transgenic mice is associated with the up-regulation or facilitation of an opiate-mediated intrinsic antinociceptive mechanism. This is a novel observation because the genetic manipulation in this transgenic mouse results in a transient over-expression of nerve growth factor during development that leads to the formation of ectopic primary afferent fibres in the spinal cord containing substance P. These fibres persist indefinitely after the nerve growth factor levels return to normal. Opioid mechanisms, which are likely of dorsal horn origin, do not fall under the direct influence of nerve growth factor mechanisms and therefore the intriguing possibility is raised that opioid mechanisms in the spinal cord are regulated at least in part by substance P-related mechanisms.

Analgesics, Opioid↗

PubMed2000

Perinatal asphyxia results in changes in presynaptic bouton number in striatum and cerebral cortex-a stereological and behavioral analysis.

Deficits in cognitive function have been related to quantitative changes in synaptic population, particularly in the cerebral cortex. Here, we used an established model of perinatal asphyxia that induces morphological changes, i.e. neuron loss in the cerebral cortex and striatum, as well as behavioural deficits. We hypothesized that perinatal asphyxia may lead to a neurodegenerative process resulting in cognitive impairment and altered presynaptic bouton numbers in adult rats. We studied cognitive performance at 18 months and presynaptic bouton numbers at 22 months following perinatal asphyxia. Data of the spatial Morris water escape task did not reveal clear memory or learning deficits in aged asphyctic rats compared to aged control rats. However, a memory impairment in aged rats versus young rats was observed, which was more pronounced in asphyctic rats. We found an increase in presynaptic bouton density in the parietal cortex, whereas no changes were found in striatum and frontal cortex in asphyctic rats. An increase of striatal volume was observed in asphyctic rats, leading to an increase in presynaptic bouton numbers in this area. These findings stress the issue that volume measurements have to be taken into account when determining presynaptic bouton density. Furthermore, perinatal asphyxia led to region-specific changes in presynaptic bouton numbers and it worsened the age-related cognitive impairment. These results suggest that perinatal asphyxia induced neuronal loss, which is compensated for by an increase in presynaptic bouton numbers.

Adult↗

PubMed2000

NGF over-expression during development leads to permanent alterations in innervation in the spinal cord and in behavioural responses to sensory stimuli.

Transgenic mice expressing nerve growth factor (NGF) under the control of a myelin basic protein promoter display above normal NGF levels in the spinal white matter from birth to the age of 2 months. These transient high levels of NGF result in a lasting hyper-innervation of the spinal white matter by ectopic Substance P (SP)-immunoreactive (IR) sensory fibres. Ultrastructural studies in adult transgenic mice demonstrated that the SP-containing fibres establish synapses on neuronal dendrites in the white matter and that most such dendrites express SP receptors. The transgenic animals display a stimulus-induced hyperalgesia and allodynia in a test measuring the latency to tail withdrawal following a heat stimulus. The hyperalgesia and allodynia were reversed by systemic administration of SP receptor or NMDA receptor antagonists. Surprisingly, the application of morphine resulted in an increase in withdrawal latency which was greater than that observed in non-transgenic controls.

Animals↗

PubMed2000

A designed peptidomimetic agonistic ligand of TrkA nerve growth factor receptors.

A proteolytically stable small molecule beta-turn peptidomimetic, termed D3, was identified as an agonist of the TrkA neurotrophin receptor. D3 binds the Ig-like C2 region of the extracellular domain of TrkA, competes the binding of another TrkA agonist, affords selective trophic protection to TrkA-expressing cell lines and neuronal primary cultures, and induces the differentiation of primary neuronal cultures. These results indicate that a small beta-turn peptidomimetic can activate a tyrosine kinase neurotrophin receptor that normally binds a relatively large protein ligand. Agents such as D3 that bind the extracellular domain of Trk receptors will be useful pharmacological agents to address disorders where Trk receptors play a role, by targeting populations selectively.

Animals↗

PubMed1999

Phosphorylation of mitogen-activated protein kinase is altered in neuroectodermal cells overexpressing the human amyloid precursor protein 751 isoform.

The aberrant expression or processing of the amyloid precursor protein (APP) is the only known genetic basis for presenile familial Alzheimer's disease, and the molecular connection between APP and tau has been perplexing. Attention has focused on proline-directed serine/threonine kinases as mediating the cytoskeletal modifications of Alzheimer's disease, and we show that overexpression of APP can influence the activation of a candidate kinase, the mitogen-activated protein kinase (MAPK). In murine embryonal carcinoma cells stably transfected with the human 751 isoform of APP, we observed steady-state hyperactivation of p42(MAPK) concomitant with APP overexpression 3 days after neuroectodermal differentiation. In more mature differentiated cells, immunocytochemical analysis revealed enhanced basal somatic and nuclear immunoreactivity for phosphorylated MAPK coupled with an attenuated phosphorylation response to growth factor stimulation. Our results suggest that APP can influence the MAPK signaling pathway in such a way that the absolute and time-dependent activation required for discrimination of the appropriate downstream response are compromised. Such an effect would have important consequences for the functioning of cells coincidentally expressing both proteins, a situation that occurs in neuronal populations vulnerable to Alzheimer's disease pathology.

Amyloid beta-Protein Precursor↗

PubMed1999

Ectopic substance P-immunoreactive boutons are preferentially presynaptic to neurokinin-1 receptor immunoreactive dendrites in the spinal white matter of transgenic mice.

A recent immunocytochemical study has shown that substance P (SP) preferentially innervates targets expressing the neurokinin-1 receptor (NK-1r) in the superficial spinal dorsal horn of the rat. Based on these findings, we decided to further investigate the relationship between SP and the NK-1r in a transgenic mouse model in which SP fibres are ectopically located. Double-labelling immunocytochemistry at both the light and electron microscopic levels was performed to study the association between SP and the NK-1r in the spinal white matter of both control and transgenic mice. Light microscopy revealed NK-1r-immunoreactive (IR) dendrites in the white matter of the dorsolateral funiculus in both control and transgenic mice. In transgenic mice, but not in controls, SP-IR fibres were observed in close proximity to the NK-1r-IR dendrites in the white matter. At the ultrastructural level, SP-IR boutons were apposed to NK-1r-IR dendrites in the dorsolateral funiculus of transgenic mice, and a synapse was frequently observed as well. These results indicate that, even in conditions in which SP fibres are ectopically located, they still preferentially innervate targets expressing the NK-1r.

Animals↗

PubMed1999

Reorganization of cholinergic terminals in the cerebral cortex and hippocampus in transgenic mice carrying mutated presenilin-1 and amyloid precursor protein transgenes.

Cholinergic deficits are one of the most consistent neuropathological landmarks in Alzheimer's disease (AD). We have examined transgenic mouse models (PS1M146L, APPK670N,M671L) and a doubly transgenic line (APPK670N,M671L + PS1M146L) that overexpress mutated AD-related genes [presenilin-1 (PS1) and the amyloid precursor protein (APP)] to investigate the effect of AD-related gene overexpression and/or amyloidosis on cholinergic parameters. The size of the basal forebrain cholinergic neurons and the pattern of cholinergic synapses in the hippocampus and cerebral cortex were revealed by immunohistochemical staining for choline acetyltransferase and the vesicular acetylcholine transporter, respectively. At the time point studied (8 months), no apparent changes in either the size or density of cholinergic synapses were found in the PS1M146L mutant relative to the nontransgenic controls. However, the APPK670N,M671L mutant showed a significant elevation in the density of cholinergic synapses in the frontal and parietal cortices. Most importantly, the double mutant (APPK670N,M671L + PS1M146L), which had extensive amyloidosis, demonstrated a prominent diminution in the density of cholinergic synapses in the frontal cortex and a reduction in the size of these synapses in the frontal cortex and hippocampus. Nonetheless, no significant changes in the size of basal forebrain cholinergic neurons were observed in these three mutants. This study shows a novel role of APP and a synergistic effect of APP and PS1 that correlates with amyloid load on the reorganization of the cholinergic network in the cerebral cortex and hippocampus at the time point studied.

Acetylcholine↗

PubMed1999

A nerve growth factor mimetic TrkA antagonist causes withdrawal of cortical cholinergic boutons in the adult rat.

Cholinergic neurons respond to the administration of nerve growth factor (NGF) in vivo with a prominent and selective increase of choline acetyl transferase activity. This suggests the possible involvement of endogenous NGF, acting through its receptor TrkA, in the maintenance of central nervous system cholinergic synapses in the adult rat brain. To test this hypothesis, a small peptide, C(92-96), that blocks NGF-TrkA interactions was delivered stereotactically into the rat cortex over a 2-week period, and its effect and potency were compared with those of an anti-NGF monoclonal antibody (mAb NGF30). Two presynaptic antigenic sites were studied by immunoreactivity, and the number of presynaptic sites was counted by using an image analysis system. Synaptophysin was used as a marker for overall cortical synapses, and the vesicular acetylcholine transporter was used as a marker for cortical cholinergic presynaptic sites. No significant variations in the number of synaptophysin-immunoreactive sites were observed. However, both mAb NGF30 and the TrkA antagonist C(92-96) provoked a significant decrease in the number and size of vesicular acetylcholine transporter-IR sites, with the losses being more marked in the C(92-96) treated rats. These observations support the notion that endogenously produced NGF acting through TrkA receptors is involved in the maintenance of the cholinergic phenotype in the normal, adult rat brain and supports the idea that NGF normally plays a role in the continual remodeling of neural circuits during adulthood. The development of neurotrophin mimetics with antagonistic and eventually agonist action may contribute to therapeutic strategies for central nervous system degeneration and trauma.

Animals↗

PubMed1999

Mitochondrial abnormalities in neuroectodermal cells stably expressing human amyloid precursor protein (hAPP751).

Metabolic hypofunction is a common finding in a number of neurodegenerative diseases, including Alzheimer's disease (AD). The strong linkage between the amyloid precursor protein (APP) and AD led us to examine whether over-expression of this protein in CNS-type cells had an effect on mitochondria. We found abnormal morphology in mitochondria of the neuroectodermal progeny of P19 cells stably transfected with human APP751. In addition, the mitochondria of APP-transfected clones had a decreased mitochondrial membrane potential. These changes were independent of Abeta toxicity and distinct from complex I inhibition. Our results have important implications for the earliest events in the pathophysiology of AD and, by extrapolation, for intervention therapies.

Amyloid beta-Protein Precursor↗

PubMed1999

Transgenic mice over-expressing substance P exhibit allodynia and hyperalgesia which are reversed by substance P and N-methyl-D-aspartate receptor antagonists.

A transgenic mouse has been developed which, during development, over-expresses nerve growth factor under the control of a myelin basic protein promoter. These animals display an ectopic network of substance P-containing sensory fibers in the white matter of the spinal cord. To study the functional significance of this model to nociception, these mice were studied in a test measuring the latency to tail withdrawal from a noxious radiant heat stimulus. Baseline reaction times were significantly less in transgenic mice, suggesting thermal allodynia. A mechanical stimulus was then applied to the tip of the tail at either 450 g or 1400 g for 2 s and tail withdrawal readings were taken for another 10 min. In control mice, the 450 g stimulus was without effect, suggesting that it is normally innocuous. In transgenic mice, this stimulus induced a transient decrease in withdrawal latency at 1 min. Thus, transgenic mice exhibited mechanical allodynia. The 1400 g stimulus decreased withdrawal latency in both transgenic and control mice. However, the response was greater in transgenic mice, indicating that they exhibited mechanical hyperalgesia. The neurokinin-1 receptor antagonist CP-96,345, but not the inactive stereoisomer CP-96,344, administered subcutaneously 30 min before the 450 g stimulus, blocked the stimulation-induced allodynia in transgenic mice, and revealed a transient antinociception in transgenic and control mice. Ketamine, an N-methyl-D-aspartate receptor antagonist, given intraperitoneally 10 min before 450 g stimulation, blocked the allodynia in transgenic mice. These results indicate that these transgenic mice display hyperalgesia and allodynia, and that these nociceptive responses are reversed by substance P and N-methyl-D-aspartate receptor antagonists.

Analgesics↗

PubMed1998

A TrkA-selective, fast internalizing nerve growth factor-antibody complex induces trophic but not neuritogenic signals.

Nerve growth factor (NGF) is a neurotrophin that induces neuritogenic and trophic signals by binding to TrkA and/or p75 receptors. We report a comparative study of the binding, internalization, and biological activity of NGF versus that of NGF in association with an anti-NGF monoclonal antibody (mAb NGF30), directed against the C termini of NGF. NGF.mAb complexes do not bind p75 effectively but bind TrkA with high affinity. After binding, NGF. mAb complexes stimulate internalization faster and to a larger degree than NGF. NGF.mAb-induced activation of TrkA, Shc, and MAPK is transient compared with NGF-induced activation; yet NGF and NGF. mAb afford identical trophic responses. In contrast, NGF induces Suc-1-associated neurotrophic activating protein phosphorylation and neuritogenic differentiation, but NGF.mAb does not. Thus, an absolute separation of trophic and neuritogenic function is seen for NGF.mAb, suggesting that biological response modifiers of neurotrophins can afford ligands with selected activities.

Antibodies, Monoclonal↗

PubMed1998

Preferential synaptic relationships between substance P-immunoreactive boutons and neurokinin 1 receptor sites in the rat spinal cord.

Substance P plays an important role in the transmission of pain-related information in the dorsal horn of the spinal cord. Recent immunocytochemical studies have shown a mismatch between the distribution of substance P and its receptor in the superficial laminae of the dorsal horn. Because such a mismatch was not observed by using classical radioligand binding studies, we decided to investigate further the issue of the relationship between substance P and its receptor by using an antibody raised against a portion of the carboxyl terminal of the neurokinin 1 receptor and a bispecific monoclonal antibodies against substance P and horseradish peroxidase. Light microscopy revealed a good correlation between the distributions of substance P and the neurokinin 1 receptor, both being localized with highest densities in lamina I and outer lamina II of the spinal dorsal horn. An ultrastructural double-labeling study, combining preembedding immunogold with enzyme-based immunocytochemistry, showed that most neurokinin 1 receptor immunoreactive dendrites were apposed by substance P containing boutons. A detailed quantitative analysis revealed that neurokinin 1 receptor immunoreactive dendrites received more appositions and synapses from substance P immunoreactive terminals than those not expressing the neurokinin 1 receptor. Such preferential innervation by substance P occurred in all superficial dorsal horn laminae even though neurokinin 1 receptor immunoreactive dendrites were a minority of the total number of dendritic profiles in the above laminae. These results suggest that, contrary to the belief that neuropeptides act in a diffuse manner at a considerable distance from their sites of release, substance P should act on profiles expressing the neurokinin 1 receptor at a short distance from its site of release.

Afferent Pathways↗

PubMed1998

Analysis of c-Fos and glial fibrillary acidic protein (GFAP) expression following topical application of potassium chloride (KCl) to the brain surface.

Application of high K+ concentrations to a limited area of the brain surface is known to trigger spreading depression. We used this model to observe the response of cortical areas, distant to the exposed site, at the cellular level. Immunostaining of glial fibrillary acidic protein (GFAP) and of the proto-oncogene c-Fos was analyzed in brain sections at different times after K+ application. Piriform and parietal cortices, as observed in coronal sections located 3 mm rostrally from the center of the stimulated area and ipsilateral to it, showed a dramatic increase in immunostaining for both markers. However, the time course for such increments was different. c-Fos protein(s) expression was high at 1.5 h and decreased at 24 h after K+ exposure and c-fos mRNA expression correlated with the immunohistochemical results. At these initial times GFAP immunoreactivity was still low but began to rise between 2 and 7 days after treatment in exactly the same areas where c-Fos expression had been up-regulated. No significant effect, for either marker, was evident in the contralateral piriform or parietal cortices. In addition, we studied the effects of the NMDA antagonist MK-801 (4 mg/kg i.p.) on the expression of mRNA for GFAP and c-fos and demonstrated a marked reduction in the upregulation of these genes.

Administration, Topical↗