Biomedical subjects

Matilde Achaval

Publications and source records attributed to Matilde Achaval.

10 recordsLinked to original sources

PubMed2005

Chronic bilateral common carotid artery occlusion: a model for ocular ischemic syndrome in the rat.

BACKGROUND: Ocular ischemic syndrome is a devastating eye disease caused by severe carotid artery stenosis. The reduction of blood flow produced by bilateral common carotid artery occlusion (BCCAO) of rats for 7 days induces events related to gliosis with no evident histological damage. However, retinal degeneration and cellular death occur after 90 days of BCCAO. Our purpose has been to investigate the effects of BCCAO for 30 days in the retina of adult rats. METHODS: Adult Wistar rats were submitted to BCCAO or sham surgery. Both direct and consensual pupillary light reflexes were investigated before and after surgery, everyday for the first week and weekly for 30 days. After 1 month, eyes were enucleated and embedded in paraffin. The retinal ganglion cell (RGC) density and thickness of the internal plexiform (IPL), internal nuclear, outer plexiform, and outer nuclear layers were estimated. RESULTS: Four rats of the BCCAO group (50%) lost the direct pupillary reflex in both eyes, three rats (37%) lost this reflex in one eye, and only one (13%) maintained it in both eyes. RGC density (cells/mm) was diminished in the BCCAO group, and a significant decrease was found in the total retina and IPL thickness; however, no changes were evident in the other layers. BCCAO pupillary-reflex-negative rats presented with a significant decrease in total retinal thickness and retinal ganglion cell density compared with the sham group. Both BCCAO pupillary-reflex-positive) and -negative rats showed a decrease in IPL compared with the sham group. CONCLUSION: This study demonstrates that BCCAO for 30 days induces functional and morphological damage to the retina with loss of the pupillary reflex and a decrease in IPL thickness and RGC number. We suggest that this protocol might be used as a model for ocular ischemic syndrome in the rat.

Animals↗

PubMed2005

Distribution and ontogeny of glial fibrillary acidic protein in the snail Megalobulimus abbreviatus.

Glial fibrillary acidic protein (GFAP) is the major component of intermediate glial filaments in the central nervous system of many vertebrates and invertebrates. In vertebrates, this protein is mainly expressed in mature astrocytes and provides structural cell stability. The highly conserved structure and glial specificity of this protein have allowed studies of ontogeny and phylogeny using antibodies. The present study investigated the ontogenetic profile and molecular weight of GFAP in the snail, Megalobulimus abbreviatus, particularly in cerebral ganglia and subesophageal mass, by immunohistochemistry and immunoblotting. Our results confirm and extend previous studies about glial intermediate filaments in snails, showing: (i) a higher GFAP content in cerebral ganglia than in subesophageal mass; (ii) a developmental increase of GFAP immunocontent in cerebral ganglia, as described in Vertebrates; and (iii) an electrophoretic band for GFAP of approximately 55 kDa.

Animals↗

PubMed2004

Carbohydrate metabolism in the central nervous system of the megalobulimus oblongus snail during anoxia exposure and post-anoxia recovery.

The effects of anoxic exposure and the post-anoxia aerobic recovery period on carbohydrate metabolism in the central nervous system (CNS) of the land snail Megalobulimus oblongus, an anoxia-tolerant land gastropod, were studied. The snails were exposed to anoxia for periods of 1.5, 3, 6, 12, 18, or 24 hr. In order to study the post-anoxia recovery phase, snails exposed to a 3-hr period of anoxia were returned to aerobic conditions for 1.5, 3, 6, or 15 hr. Glycogen and glucose concentrations in the CNS, hemolymph glucose concentration, and glycogen phosphorylase (active form, GPa) activity in the CNS were analyzed. Anoxia does not significantly affect the concentration of CNS glucose but induces hyperglycemia and a reduction of CNS GPa activity. The glycogen concentration was decreased at 12 hr of anoxia; however, by 18 and 24 hr in anoxia, the glycogen content was not significantly different from basal control values. During the post-anoxia period, the reduction in GPa activity and the increased hemolymph glucose concentration induced by anoxia returned to control values. These results suggest that the CNS of M. oblongus may use hemolymph glucose to fulfill the metabolic demands during anoxia. However, the hypothesis of tissue metabolic arrest cannot be excluded.

Adaptation, Physiological↗

PubMed2004

Tactile stimulation and maternal separation prevent hippocampal damage in rats submitted to neonatal hypoxia-ischemia.

Unilateral neonatal hypoxia-ischemia causes important damage to the hippocampus of the hemisphere ipsilateral to carotid artery occlusion; two forms of neonatal handling, tactile stimulation and maternal separation for a short period, have been shown to produce functional/behavioral protection in distinct models of CNS challenge. In this paper we investigated whether neonatal handling could alter the hippocampal damage caused by neonatal hypoxia-ischemia (HI) in the Wistar rat. Pups at postnatal day 7, P7, received HI (8% O(2)-92% N(2)) for 90 min and were submitted to neonatal handling, tactile stimulation of maternal separation daily, from P8 to P21, for 10 min. On adulthood, hippocampal volume was analyzed by stereological techniques, along with measures of cortical thickness and hemispheric area at the level -3.30 mm from bregma. HI caused a reduction of volume of whole hippocampus, of Amon's horn and of dentate gyrus, with no effect on cortical and hemispheric measures; neonatal handling prevented such effect. This is the first report showing that both tactile stimulation and neonatal handling exert a morphological neuroprotective action for HI-induced damage to the hippocampus.

Animals↗

PubMed2004

Complete sciatic nerve transection induces increase of neuropeptide Y-like immunoreactivity in primary sensory neurons and spinal cord of frogs.

Neuropeptide Y (NPY) was immunohistochemically investigated in the frog spinal cord and dorsal root ganglia after axotomy. In normal ganglia, moderate NPY-like immunoreactivity (NPY-IR) prevailed in large and medium cells. In the spinal cord, the NPY-IR was densest in the dorsal part of the lateral funiculus. Other fibers and neurons NPY-IR were observed in the dorsal and ventral terminal fields and mediolateral band. NPY-IR fibers were also found in the ventral horn and in the ventral and lateral funiculi. The sciatic nerve transection increased the NPY-IR in large and medium neurons of the ipsilateral and contralateral dorsal root ganglia at 3 and 7 days, but no clear change was found at 15 days. In the spinal cord, there was a bilateral increase in the NPY-IR of the dorsal part of the lateral funiculus. In the ipsilateral side, the NPY-IR was increased at 3 and 7 days but was decreased at 15 days. In the contralateral side, a significant reduction at 15 days occurred. These findings seem to favor the role of NPY in the modulation of pain-related information in frogs, suggesting that this role of NPY may have appeared early in vertebrate evolution.

Animals↗

PubMed2004

Somatostatin-, calcitonin gene-related peptide, and gamma-aminobutyric acid-like immunoreactivitity in the frog lumbosacral spinal cord: distribution and effects of sciatic nerve transection.

Using immunohistochemistry and optical densitometry, somatostatin (SOM), calcitonin gene-related peptide (CGRP), and gamma-aminobutyric acid (GABA) were investigated in the lumbosacral spinal cord of the frog Rana catesbeiana after sciatic nerve transection. In control animals, the densest network of the SOM-, CGRP- and GABA-like immunoreactive fibers was located in the dorsal part of the lateral funiculus. SOM and GABA-like fibers were found in the dorsal terminal field and in the mediolateral band. The latter region showed CGRP and SOM-like immunoreactive cell bodies. SOM- and GABA-like immunoreactive neurons also occurred around the cavity of the central canal, and other GABA-like fibers were found in the ventral terminal field. While the ventral horn showed scarce somatostatin-like fibers, the putative motoneurons were immunoreactive for the two peptides investigated and GABA, but only a few SOM- and GABA-like fibers occurred in the ventral funiculus. After axotomy, GABA-like immunoreactivity decreased in the dorsal part of the lateral funiculus on the same side of the lesion. The other regions remained labeled. These changes were observed at 3 days following axonal injury and persisted at 5, 8 and 15 days. There was no significant difference in the pattern of CGRP- and SOM- immunoreactivity between the axotomized and the control sides. These results are discussed in relation to the effects of the peripheral axotomy on GABA, SOM, and CGRP expression in vertebrates, emphasizing the use of frogs as a model to study the effects of peripheral nerve injury.

Animals↗

PubMed2003

Failure of estrogen to protect the substantia nigra pars compacta of female rats from lesion induced by 6-hydroxydopamine.

The immunostaining for tyrosine hydroxylase (TH) in the substantia nigra pars compacta (SNpc) and in the ventral tegmental area (VTA) after intranigral infusion of 6-hydroxydopamine (6-OHDA, 6 microg/side) was analyzed in ovariectomized adult female Wistar rats. Estrogen replacement for 52 days (400-microg 17-beta-estradiol capsules) did not prevent the loss of TH-immunoreactive cells induced by 6-OHDA in the SNpc. This result indicates that the neuroprotective effect of dopaminergic mesencephalic cells is not observed with long-term estrogen replacement.

Animals↗

PubMed2003

Neonatal cerebral hypoxia-ischemia causes lateralized memory impairments in the adult rat.

Neonatal hypoxia-ischemia (HI) has been extensively studied in a rat model characterized by unilateral brain damage (Rice-Vannucci Model). However, as well as in humans, each rat brain hemisphere is distinctly involved in cognitive functions, as for example retrieval of emotionally based memory, and neurochemical asymmetries have been described. In this paper we investigated whether hypoxia-ischemia could cause distinct cognitive deficits depending on which hemisphere is damaged. Seven-day-old male Wistar rats were submitted to permanent occlusion of left or right common carotid artery and were exposed to a mixture of 8% oxygen-92% nitrogen for 2.5 h. On adulthood, these rats were trained in step-down inhibitory avoidance and in two tasks in the Morris water maze. Both experimental groups (right and left lesioned) showed a deficit of retrieval in the inhibitory avoidance task compared to controls, although rats with right hemisphere lesion showed a significantly greater deficit than the left damaged group (P<0.05). In the Morris maze, both damaged groups presented cognitive deficits in the reference memory task (P<0.05), however only the right damaged group had an impairment in the working memory task. Brain coronal areas, at levels +1.20 and -3.30 mm from bregma of both HI groups were smaller than those of control, with no differences between the right and left damaged groups (P<0.05). These results show that cerebral hypoxia-ischemia in neonatal rats causes asymmetric behavioral outcomes depending on which of the hemispheres is lesioned and support the hypothesis of lateralization of cognitive functions in the rodent brain.

Animals↗

PubMed2002

Glial fibrillary acidic protein immunodetection and immunoreactivity in the anterior and posterior medial amygdala of male and female rats.

The medial amygdala (MeA) has receptors for gonadal hormones and modulates reproductive behaviors in rats. Adult male and female rats were used for the immunodetection, a less accurate technique, and the immunohistochemistry for the astrocytic marker glial fibrillary acidic protein (GFAP) in the anterior and posterior MeA. Both procedures were done using polyclonal anti-GFAP and were quantified by densitometry. The first technique provided no evidence for a difference between sexes in the immunocontent of GFAP in any region of the MeA (p > 0.1). Nevertheless, the measure of the intensity of GFAP immunoreactivity (GFAP-IR) showed that females had a higher GFAP-IR in the posterodorsal (p < 0.01) and in the posteroventral subregions of the MeA (p < 0.01) than males. No sex difference was found in its anterodorsal part (p > 0.1). The present results point out the differences between these two above-mentioned techniques but add a new finding to the previously described sexual dimorphism in the MeA, i.e., the GFAP-IR. Data also suggest that probably astrocytes can be affected by sex steroids in this brain area. It is likely that this regionally specific difference in the GFAP-IR may contribute to the distinct functional roles that the MeA subregions have in male and female rats.

Amygdala↗

PubMed2002

Sciatic nerve transection decrease substance P immunoreactivity in the lumbosacral spinal cord of the frog (Rana catesbeiana).

Using immunohistochemistry and optical densitometry, substance P (SP) was investigated in the lumbar spinal cord of the frog Rana catesbeiana after sciatic nerve transection. In control animals, there was a high density of SP fibers in the Lissauer's tract and in the mediolateral band of the dorsal gray matter. Other SP immunoreactive fibers were observed in the dorsal part of the lateral funiculus and in the ventral horn. No SP label was found in any cell bodies. After axotomy, SP immunoreactive fibers decreased in the Lissauer's tract on the same side of the lesion. The other regions remained labeled. The changes were observed at 3 days following axonal injury and persisted at 5, 8 and 15 days. At 20 days, there was no significant difference between the axotomized side and the control one, thus indicating a recovery of the SP expression. These results indicate that the frog may be used as a model to study the effects of peripheral axotomy, contributing to elucidate the SP actions in the pain neuropath.

Animals↗