Serotonergic immunoreactivity in the pedal ganglia of the pulmonate snail Megalobulimus abbreviatus after thermal stimulus: A semi-quantitative analysis

Using an immunohistochemical procedure and optical densitometry, the distribution of neurons containing serotonin (5-HT) was investigated in the pedal ganglia of Megalobulimus abbreviatus after thermal "non-functional stimulus" (22 degrees C) and stressful thermal conditions (50 degrees C). The animals were sacrificed at different times (3 h, 6 h and 24 h) following these stimuli. In control animals, the results showed the location of these serotonergic immunoreactive elements (5HT-ir) in this ganglion to be similar to those shown in other studies, where the anterior region of ventral sections showed the largest number of 5HT-ir neurons. In the anterior neurons, significant differences (p < 0.01) were observed between the groups of animals stimulated at 50 degrees C and 22 degrees C and sacrificed after 6 h. In the medial neurons, significant differences (p < 0.05) were observed between the control group and the groups of animals stimulated at 50 degrees C and sacrificed after 6 and 24 h. Neuropilar area 1 showed differences (p < 0.01) in 5HT-ir between the control group and the groups of animals stimulated at 50 degrees C and sacrificed after 3 and 24 h. Neuropilar area 2 showed a significant difference (p < 0.05) between the groups of animals stimulated at 22 degrees C and sacrificed after 3 and 24 h. These results suggest the involvement of 5-HT in the nociceptive circuit of M. abbreviatus, mainly that of the medial neurons and neuropilar area 1, which showed increases in 5HT-ir after thermal aversive stimuli. These results could be helpful in drawing cellular homologies with other gastropods.

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.

The terrestrial Gastropoda Megalobulimus abbreviatus as a useful model for nociceptive experiments: effects of morphine and naloxone on thermal avoidance behavior

We describe the behavior of the snail Megalobulimus abbreviatus upon receiving thermal stimuli and the effects of pretreatment with morphine and naloxone on behavior after a thermal stimulus, in order to establish a useful model for nociceptive experiments. Snails submitted to non-functional (22 degrees C) and non-thermal hot-plate stress (30 degrees C) only displayed exploratory behavior. However, the animals submitted to a thermal stimulus (50 degrees C) displayed biphasic avoidance behavior. Latency was measured from the time the animal was placed on the hot plate to the time when the animal lifted the head-foot complex 1 cm from the substrate, indicating aversive thermal behavior. Other animals were pretreated with morphine (5, 10, 20 mg/kg) or naloxone (2.5, 5.0, 7.5 mg/kg) 15 min prior to receiving a thermal stimulus (50 degrees C; N = 9 in each group). The results (means +/- SD) showed an extremely significant difference in response latency between the group treated with 20 mg/kg morphine (63.18 +/- 14.47 s) and the other experimental groups (P < 0.001). With 2.5 mg/kg (16.26 +/- 3.19 s), 5.0 mg/kg (11.53 +/- 1.64 s) and 7.5 mg/kg naloxone (7.38 +/- 1.6 s), there was a significant, not dose-dependent decrease in latency compared to the control (33.44 +/- 8.53 s) and saline groups (29.1 +/- 9.91 s). No statistically significant difference was found between the naloxone-treated groups. With naloxone plus morphine, there was a significant decrease in latency when compared to all other groups (minimum 64% in the saline group and maximum 83.2% decrease in the morphine group). These results provide evidence of the involvement of endogenous opioid peptides in the control of thermal withdrawal behavior in this snail, and reveal a stereotyped and reproducible avoidance behavior for this snail species, which could be studied in other pharmacological and neurophysiological studies.

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.

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.

Localization of acid phosphatase activity in the testis of two teleostean species (Oreochromis niloticus and Odonthestes perugiae)

Acid phosphatase (AcP) activity was investigated in the testes of two species of teleosts in two seasons: summer and winter. AcP activity was detected in Sertoli cells from tilapia (Oreochromis niloticus) only during the nonreproductive period of its annual cycle, corresponding to the winter months. In kingfish (Odonthestes perugiae), the enzymatic reaction was identified during the non-reproductive period (summer) in epithelial cells of the efferent ducts but not in Sertoli cells. These data suggest that the enzyme is involved in the absorption of residual spermatid cytoplasm and as well as in the removal of spermatozoa remaining after the reproductive period. In kingfish, this heterophagous function is carried out by the efferent duct cells and not by Sertoli cells.

Influence of sex, estrous cycle and motherhood on dendritic spine density in the rat medial amygdala revealed by the Golgi method

The medial nucleus of the amygdala (MeA), a sexually dimorphic area, contains estrogen and androgen receptors and has an integrative role in behavioral, vegetative and endocrine activities of rats. The density of dendritic spines along the first 40 microm of dendritic length was studied in neurons from the anterodorsal (MeAD), posterodorsal (MePD) and posteroventral (MePV) aspects of the MeA in males, in virgin females during the four phases of the estrous cycle and in multiparous females in diestrus. The single-section Golgi method was employed (N=48 observations per experimental group). In the three MeA subnuclei males showed more dendritic spines than virgin females (P<0.001), with the only exception being the MePD data of females in diestrus (P>0.05). In virgin females, whereas more dendritic spines were found in diestrus, a decline in these values was found during the proestrus, estrus and metaestrus in the MePD and MePV (P<0.05) but not in the MeAD (P>0.05). Compared with virgin females in diestrus, postpartum rats showed more spines in the MeAD (P<0.001) and fewer in the MePD (P<0.001) but no difference was found in the MePV (P>0.05). These data suggest that there are subregion-specific differences in the density of dendritic spines within the MeA and that they appear to be affected by sex, cyclic fluctuations in the levels of ovarian steroids and following pregnancy in rats. These findings may add to the understanding of the MeA neuronal plastic changes that affect the ongoing processing of sensory information and the organization of the neuroendocrine and behavioral basis of reproduction.

Monoamines in the pedal plexus of the land snail Megalobulimus oblongus (Gastropoda, Pulmonata)

In molluscs, the number of peripheral neurons far exceeds those found in the central nervous system. Although previous studies on the morphology of the peripheral nervous system exist, details of its organization remain unknown. Moreover, the foot of the terrestrial species has been studied less than that of the aquatic species. As this knowledge is essential for our experimental model, the pulmonate gastropod Megalobulimus oblongus, the aim of the present study was to investigate monoamines in the pedal plexus of this snail using two procedures: glyoxylic acid histofluorescence to identify monoaminergic structures, and the unlabeled antibody peroxidase anti-peroxidase method using antiserum to detect the serotonergic component of the plexus. Adult land snails weighing 48-80 g, obtained from the counties of Barra do Ribeiro and Charqueadas (RS, Brazil), were utilized. Monoaminergic fibers were detected throughout the pedal musculature. Blue fluorescence (catecholamines, probably dopamine) was observed in nerve branches, pedal and subepithelial plexuses, and in the pedal muscle cells. Yellow fluorescence (serotonin) was only observed in thick nerves and in muscle cells. However, when immunohistochemical methods were used, serotonergic fibers were detected in the pedal nerve branches, the pedal and subepithelial plexuses, the basal and lateral zones of the ventral integument epithelial cells, in the pedal ganglion neurons and beneath the ventral epithelium. These findings suggest catecholaminergic and serotonergic involvement in locomotion and modulation of both the pedal ganglion interneurons and sensory information. Knowledge of monoaminergic distribution in this snail s foot is important for understanding the pharmacological control of reflexive responses and locomotive behavior.

Somatostatin-, calcitonin gene-related peptide, and γ-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.

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.

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.

Vascular supply of the central nervous system of the land snail Megalobulimus oblongus (Gastropoda, Pulmonata)

The vascularization of the central nervous system of the snail Megalobulimus oblongus was studied by injection of carmine-gelatin solution into the arterial system and using a histochemical technique for the detection of alkaline phosphatase. The central nervous system of M. oblongus is irrigated by the anterior aorta, from which a series of small branches emerge that supply the subesophageal nervous ganglia. In turn, these branches give rise to a series of smaller vessels that irrigate the buccal bulb, the anterior portion of the foot, the cerebral ganglia, the dorsal body gland, and the anterior portion of the reproductive system. No hemolymph vessels were detected within nervous tissue although such vessels were found in the periganglionic connective sheath. This connective sheath contains vascular loops and had a series of overlaps and projections that follow the contour of the nervous ganglia. This arrangement permits a larger area of interaction between the surface of the nervous tissue and the hemolymph and reduces the distance between the deepest portion of a given ganglion and the hemolymph vessels.

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.

Substance P immunoreactivity in the lumbar spinal cord of the turtle Trachemys dorbigni following peripheral nerve injury

Immunoreactive substance P was investigated in turtle lumbar spinal cord after sciatic nerve transection. In control animals immunoreactive fibers were densest in synaptic field Ia, where the longest axons invaded synaptic field III. Positive neuronal bodies were identified in the lateral column of the dorsal horn and substance P immunoreactive varicosities were observed in the ventral horn, in close relationship with presumed motoneurons. Other varicosities appeared in the lateral and anterior funiculi. After axotomy, substance P immunoreactive fibers were reduced slightly on the side of the lesion, which was located in long fibers that invaded synaptic field III and in the varicosities of the lateral and anterior funiculus. The changes were observed at 7 days after axonal injury and persisted at 15, 30, 60 and 90 days after the lesion. These findings show that turtles should be considered as a model to study the role of substance P in peripheral axonal injury, since the distribution and temporal changes of substance P were similar to those found in mammals.

The gross anatomy of the nervous system of Bothriurus bonariensis (L. C. Koch, 1842). (Scorpiones, Bothriuridae)

The nervous system of the order Scorpiones appears to have a common organizational structure. The combination of an anatomical study using methylene blue as the contrast medium together with a histological analysis using hematoxylin-eosin and Heindenhain's iron hematoxylin techniques permitted the identification of a large number of nerves in B. bonariensis. Many of these are also present in a variety of other species of scorpions, belonging to distinct families of the order Scorpiones. Nevertheless, two pairs of nerves from B. bonariensis originating in the cheliceral ganglion, one pair of esophageal nerves and one pair of nerves from the aortic arch, appear to diverge from this basic organization. They have not been previously described, nor have any equivalents been reported in research on other scorpion species, in which the current homological criteria have been employed.

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.

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.

Neurochemical characterization of traumatic brain injury in humans

Trauma is the leading cause of death in individuals between the ages of 1 and 44 years. And, in the case of severe head injury mortality can reach as high as 35-70%. Despite this fact, there has been little progress in the development of effective pharmacological agents to protect brain injured patients. To date, there is little data on the mechanisms involved in neuronal cellular insult after severe head injury, especially in humans. Glutamate acts both as a primary excitatory neurotransmitter and a potential neurotoxin within the mammalian brain. Evidence indicates that hyperactivity of the glutamate system contributes to neuronal death in brain trauma. Also, in animal models of neurotrauma, this neural injury is followed by gliosis which has been linked to the severity of brain injury. To investigate the glutamate system in brain trauma, we carried out [3H]glutamate and [3H]MK801 (a noncompetitive NMDA-receptor antagonist) binding and [3H]glutamate uptake assays in human cerebral cortex preparations obtained from severely brain injured and control victims. Additionally, to investigate gliosis following brain injury, we performed GFAP immunohistochemistry. There were no significant differences in [3H]glutamate binding (affinity or density of sites) between the control and head injured groups. In contrast, cerebral cortical [3H]MK801 binding revealed both a significant increase in the density of sites (Bmax) and a decrease in the dissociation constant (Kd) in the head injured group when compared to controls. There were no significant differences in [3H]glutamate uptake between groups. The injured brains presented an increased number of GFAP-positive astrocytes and more intense GFAP reaction in comparison to control brains. In the context of traumatic brain injury, our results encourage further investigation into compounds capable of selective modulation of NMDA receptor subtype in humans while also therapeutically manipulating glial cell responses following brain trauma.

Functional activities of the amygdala: an overview

Research to date into the amygdala shows that it has an integrative role in behavioural, vegetative and endocrine activities of animals in their relation with their environment. Animal studies show that amygdala has a role in emotional response, integrating input signals and initiating activities related to them. Different nuclei seem to have different effects. A complete picture of the functional roles of the amygdala is unavailable, and it has been suggested that the amygdala is functionally and anatomically heterogeneous. Amygdaloid subnuclei appear to have a role in the modulation of fear, in memory and attention, and in some sexual and sex-related behaviour of rats. In humans, functional magnetic resonance imaging shows that the amygdala responds preferentially to emotionally charged stimuli. Bilateral amygdala damage in humans can compromise the recognition of fear in facial expressions, an important ability in social judgement. Future study of the amygdala promises to shed light on emotional disorders in humans.

Distribution of glycogen phosphorylase and cytochrome oxidase in the central nervous system of the turtle Trachemys dorbigni

Glycogen phosphorylase (GP) and cytochrome oxidase (CO) activities were mapped histochemically in the brain of the turtle Trachemys dorbigni. In the telencephalon, both activities occurred in the olfactory bulb, in all cortical areas, in the dorsal ventricular ridge, striatum, primordium hippocampi and olfactory tubercle. In the diencephalon, they were identified in some areas of the hypothalamus, and in rotundus and geniculate nuclei. Both reactions were detected in the oculomotor, trochlear, mesencephalic trigeminal nuclei, the nucleus of the posterior commissure, torus semicircularis, substantia nigra and ruber and isthmic nuclei of the mesencephalon. In all layers of the optic tectum GP activity was found, but CO only labelled the stratum griseum centrale. In the medulla oblonga both enzymes appear in the reticular, raphe and vestibular nuclei, locus coeruleus and nuclei of cranial nerves. In the cerebellum, the granular and molecular layers, and the deep cerebellar nuclei were positive for both enzymes. The Purkinje cells were only reactive for CO. In the spinal cord, motor and commissural neurones exhibited a positive reaction for the two enzymes. However, CO also occurred in the marginal nucleus and in the lateral funiculus. These results may be useful as a basis for subsequent studies on turtle brain metabolism.

Effects of inhaled furosemide on platelet-activating factor challenge in mild asthma

Furosemide (Fur) may have an anti-inflammatory effect on airways in patients with asthma although its intrinsic mechanism remains elusive. Platelet-activating factor (PAF) is a potent proinflammatory mediator that induces systemic and respiratory effects in normal control subjects and asthmatics. The aim of this study was to assess whether pretreatment with nebulized Fur (40 mg) was able to modulate PAF-induced systemic and respiratory effects in asthma. Eleven patients were studied (mean+/-sem 22+/-0.8 yrs) with mild asthma (forced expiratory volume in one second, 95+/-4%) in a randomized, double-blind, placebo-controlled, cross-over fashion, one week apart. PAF challenge (18 microg) was carried out 15 min after administration of Fur or placebo. Peripheral blood neutrophils, respiratory system resistance, and arterial blood gases were measured at baseline, and 5, 15 and 45 min after PAF; urinary cysteinyl leukotriene E4 (uLTE4) was also measured, at baseline and 120 min after PAF challenge. Although Fur did not alter PAF-induced systemic and respiratory effects, it did partially inhibit (63%; p<0.04) the increments of uLTE4 levels shown after PAF inhalation. It is concluded that furosemide is not effective in protecting against platelet-activating factor challenge in patients with asthma despite its potential inhibition of leukotriene synthesis. These findings reinforce the view that the pulmonary effects of platelet-activating factor are mediated through different pathways.

Axotomy increases NADPH-diaphorase activity in the dorsal root ganglia and lumbar spinal cord of the turtle Trachemys dorbigni

Seven days after transection of the sciatic nerve NADPH-diaphorase activity increased in the small and medium neurons of the dorsal root ganglia of the turtle. However, this increase was observed only in medium neurons for up to 90 days. At this time a bilateral increase of NADPH-diaphorase staining was observed in all areas and neuronal types of the dorsal horn, and in positive motoneurons in the lumbar spinal cord, ipsilateral to the lesion. A similar increase was also demonstrable in spinal glial and endothelial cells. These findings are discussed in relation to the role of nitric oxide in hyperalgesia and neuronal regeneration or degeneration.

Effects of gonadal hormones on the morphology of neurons from the medial amygdaloid nucleus of rats

The medial amygdala (MeA) has receptors for gonadal hormones and is a sexually dimorphic area in rats. The aims of the present work were (1) to look at sex differences and the effect of gonadal hormone withdrawal in males castrated as offspring or at adulthood on neuronal soma area in the anterior and posterior MeA and (2) to study the dendritic branching and the density of dendritic spines in neurons from the MeA of intact males and females. Animals were adult rats, for which the single-section Golgi method was used. Stellate and bitufted cells were found in the MeA. Comparing data among groups, no significant difference in cell body area was found. Dendrites divide sparingly and have very different lengths, and a statistical difference (p < 0.001, males higher than females) in the spine density in the anterior MeA, but not in the posterior MeA, was found. These results suggest that castration does not alter the somal area in males submitted to gonadectomy during the early postnatal period or at adulthood. In addition, the already described sex difference in this nucleus may be more related to the neuropil than the neuronal somal area, which may be relevant for the function of the MeA.