Brain research
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Activation of immune cells by pathogens induces the release of a variety of proinflammatory cytokines, including IL-1 beta and TNF-alpha. Previous studies using IL-1 beta have demonstrated that this cytokine can alter brain function, resulting in a variety of 'illness responses' including increased sleep, decreased food intake, fever, etc. We have recently demonstrated that i.p. ⋯ TNF-alpha on pain responsivity. These studies demonstrate that: (a) i.p. TNF-alpha produces dose-dependent hyperalgesia as measured by the tailflick test, (b) this hyperalgesia is mediated via the induced release of IL-1 beta, (c) hyperalgesia is mediated via activation of subdiaphragmatic vagal afferents, and (d) the effects of subdiaphragmatic vagotomy cannot be explained by a generalized depression of neural excitability.
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The olivary pretectal nucleus is a primary visual centre sensitive to luminance changes. It is involved in the pupillary light reflex, the consensual pupillary light reflex and related reflexes, such as the lid closure reflex whereby pupillary constriction takes place. Since the olivary pretectal nucleus is a small nucleus, previous studies using degeneration, horseradish peroxidase and radioactive amino acid tracing were limited regarding to the exclusiveness of the projections from the olivary pretectal nucleus. ⋯ The projection from the olivary pretectal nucleus to the facial nucleus which has been described to receive an input in cats could not be confirmed for the rat. The fact that the Edinger-Westphal nucleus, the interstitial nucleus of Cajal and the superior colliculus receive an input from the olivary pretectal nucleus suggests that this primary visual centre is not only involved in the pupillary light reflex, but also in controlling eye and head position and saccadic eye movements. Although visual acuity largely depends on receptive field sizes of retinal ganglion cells and their central connections, the stronger sympathetic influence during the pupillary light reflex in animals with frontally placed eyes compared to animals with laterally placed eyes may also contribute to the higher visual acuity in animals with frontally placed eyes.
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The goal of the present study was to determine the effect of acute ethanol (ETOH), administered intraperitoneally or electro-osmotically, on norepinephrine (NE) induced increases in gamma-aminobutyric acid (GABA) mediated inhibition of single cerebellar Purkinje neurons (P-cells). Male Sprague-Dawley rats (230-370g) were anesthetized with halothane and implanted with an intraperitoneal catheter for systemic administration of ETOH (1.0-1.5 g/kg) prior to the recording session. Extracellular activity of single P-cells was recorded before and after iontophoresis of GABA and NE using five-barrel glass micropipettes. ⋯ NE-induced augmentation of GABA inhibition persisted for 2-13 min longer after ETOH administration than in the pre-ETOH control period. Local electro-osmotic application of ETOH, which resulted in strong depression of spontaneous activity and caused small increases in GABA-mediated inhibition, did not directly potentiate NE-induced augmentation of GABA action. These results indicate that NE-mediated augmentation of GABA inhibition of P-cell activity is potentiated following systemic, but not local, ETOH administration.
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Diseases that affect the striatum produce movement disorders, for which rats have been a useful model. To determine the organization of functional, neural activity in the rat striatum related to motor activity, we used electrical stimulation of the motor cortex and [14C]deoxyglucose autoradiography. The stimulation produced movements of each of three body regions. ⋯ This is the first demonstration of a global striatal somatotopy that separates the limbs and vibrissae in rats. The functional average revealed by the deoxyglucose autoradiography showed a predominant isotropic or rod-like representation of sensorimotor activity for the limbs in striatum during movement and confirms aspects of the anatomy known for the corticostriate system in primates: metabolism was 'patchy,' and extended throughout long anteroposterior domains in striatum. These extensive and patchy arrangements suggest integrative, combinational and/or associative networks.
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Mild to moderate traumatic brain injury (TBI) is associated with enduring impairments of cognitive function in both humans and animals. However, few experiments have investigated the role of post-injury pharmacologic strategies for attenuating the observed cognitive impairment after TBI. This investigation examined the effects of selective blockade of the presynaptic muscarinic M2 autoreceptor with BIBN 99 on cognitive recovery following rodent TBI. ⋯ Sham-injured animals injected (s.c.) with vehicle (n = 9) or 1.0 (n = 8) mg/kg of BIBN 99 were included for comparison. On days 11-15 after injury, cognitive performance was assessed with the MWM procedure. Results of the second experiment indicated that both doses of BIBN 99 were effective in attenuating cognitive deficits in the MWM as compared to the injured-vehicle treated animals (P < 0.05 for both comparisons).(ABSTRACT TRUNCATED AT 250 WORDS)