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Results for “Neural Pathways”

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At least 199 records · Page 11Linked to original sources

PubMed2004

Functional mapping of neural pathways in rodent brain in vivo using manganese-enhanced three-dimensional magnetic resonance imaging.

This work presents three-dimensional MRI studies of rodent brain in vivo after focal and systemic administration of MnCl2. Particular emphasis is paid to the morphology and dynamics of Mn2+-induced MRI signal enhancements, and the physiological mechanisms underlying cerebral Mn2+ uptake and distribution. It turns out that intravitreal and intrahippocampal injections of MnCl2 emerge as useful tools for a delineation of major axonal connections in the intact central nervous system. Subcutaneous administrations may be exploited to highlight regions involved in fundamental brain functions such as the olfactory bulb, inferior colliculus, cerebellum and hippocampal formation. Specific insights into the processes supporting cerebral Mn2+ accumulation may be obtained by intraventricular MnCl2 injection as well as by pharmacologic modulation of, for example, hippocampal function. Taken together, Mn2+-enhanced MRI opens new ways for mapping functioning pathways in animal brain in vivo with applications ranging from assessments of transgenic animals to follow-up studies of animal models of human brain disorders.

Animals↗

PubMed1985

Influence of neural pathways on the pyrexial response to surgical trauma.

Epidural analgesia inhibits several metabolic effects of trauma. Some of these effects are generated by the endogenous fever mediator interleukin-1. Postoperative fever was therefore studied in 52 patients, 25 of whom had had epidural analgesia and 27 general anaesthesia. Transvesical prostatectomy was used as standard surgical trauma. Most of the patients had postoperative temperature rise exceeding 0.5 degree C, but the rise was not influenced by epidural analgesia. These data suggest that the release of endogenous fever mediator is not under control of afferent pathways from the region of trauma. The findings are also consistent with regulation of interleukin-1 release which is independent of adrenal stimulation, cyclic AMP or beta-endorphin, as epidural analgesia prevents postoperative increase of these hormones.

Aged↗

PubMed1980

Lack of modulation of pituitary hormone stress response by neural pathways involving opiate receptors.

To evaluate the role of the opiate-like peptidergic pathways in modulating the pituitary hormone response to stress, we measured the GH, PRL, and cortisol responses to hypoglycemia and exercise in normal subjects with and without pretreatment with naloxone, given in the centrally active dose of 0.4 mg iv. Basal serum levels of GH, PRL, and cortisol were not changed significantly by prior naloxone administration. The maximum incremental response of GH to exercise was significantly blunted (13.1 +/- 1.6 vs. 6.0 +/- 1.4; P less than 0.001) by prior naloxone administration. Pretreatment with naloxone did not affect the responses of GH, PRL, or cortisol to hypoglycemia or the PRL response to L-dopa. On the basis of these studies we conclude that the opiate-like peptidergic pathways are not important in the regulation of basal levels of GH, PRL, and cortisol and have only a modest modulating influence on the stress-induced release of the hormones, which may be obscured in the face of severe stress.

Female↗

PubMed1982

Neural pathways to lower urinary tract identified by retrograde axonal transport of horseradish peroxidase.

A new technique for tracing nerve fibers supplying specific organs by retrograde axonal transport of the enzyme horseradish peroxidase (HRP) was used to determine the innervation of various segments of the lower urinary tract. HRP was injected at the level of the bladder neck, postprostatic urethral segment, pelvic nerve, pudendal nerve, and pelvic floor musculature to determine precise nerve supply to each site, as well as possible overlap. The technique determines the exact spinal level of innervation, as well as the number of nuclei directly related to the motor neuron axons supplying innervation to each particular site. Representation of these nuclei at various levels of the spinal cord was shown in various serial sections obtained after the injection of HRP. This technique is accurate and precise; it is valuable in establishing exact neural anatomic connections between the central nervous system and target organs.

Anal Canal↗

PubMed2005

Melanin concentrating hormone (MCH): a novel neural pathway for regulation of GnRH neurons.

The link between the state of energy balance and reproductive function is well known. Thus, signals denoting negative energy balance and the accompanying hyperphagic drive are likely to be factors in the suppression of gonadotropin releasing hormone (GnRH) activity. We have previously found that appetite-regulating systems, such as neuropeptide Y (NPY) in the arcuate nucleus (ARH) and orexin in the lateral hypothalamic area (LHA), send fiber projections that come in close apposition with GnRH neurons. Furthermore, the appropriate receptors, NPY Y5 and OR-1, respectively, are coexpressed on GnRH neurons, providing neuroanatomical evidence for a direct link between the NPY and orexin systems and GnRH neurons. Therefore, these orexigenic neuropeptide systems are potential candidates that convey information about energy balance to GnRH neurons. The current studies focused on melanin concentrating hormone (MCH), another orexigenic neuropeptide system located in the LHA that is sensitive to energy balance. The results showed that MCH fiber projections came in close apposition with approximately 85-90% of GnRH cell bodies throughout the preoptic area and anterior hypothalamic area in the rat. In addition, the MCH receptor (MCHR1) was coexpressed on about 50-55% of GnRH neurons. These findings present evidence for a possible direct neuroanatomical pathway by which MCH may play a role in the regulation of GnRH neuronal function. Thus, MCH is another potential signal that may serve to integrate energy balance and reproductive function.

Animals↗

PubMed1999

A calcium/calmodulin-dependent nitric oxide synthase, NMDAR2/3 receptor subunits, and glutamate in the CNS of the cuttlefish Sepia officinalis: localization in specific neural pathways controlling the inking system.

Chemical, biochemical, and immunohistochemical evidence is reported demonstrating the presence in the brain of the cuttlefish Sepia officinalis of a Ca2+-dependent nitric oxide synthase, NMDAR2/3 receptor subunits, and glutamate, occurring in neurons and fibers functionally related to the inking system. Nitric oxide synthase activity was concentrated for the most part in the cytosolic fraction and was masked by other citrulline-forming enzyme(s). The labile nitric oxide synthase could be partially purified by ammonium sulfate precipitation of tissue extracts, followed by affinity chromatography on 2',5'-ADP-agarose and calmodulin-agarose. The resulting activity, immunolabeled at 150 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis by antibodies to rat neuronal nitric oxide synthase, depended on NADPH and tetrahydro-L-biopterin, and was inhibited by N(G)-nitro-L-arginine. NMDAR2/3 subunit-immunoreactive proteins migrating at 170 kDa could also be detected in brain extracts, along with glutamate (whole brain: 0.32 +/- 0.03 micromol of glutamate/mg of protein; optic lobes: 0.22 +/- 0.04; vertical complex: 0.65 +/- 0.06; basal lobes: 0.58 +/- 0.04; brachial lobe: 0.77 +/- 0.06; pedal lobe: 1.04 +/- 0.08; palliovisceral lobe: 0.86 +/- 0.05). Incubation of intact brains with 1.5 mM glutamate or NMDA or the nitric oxide donor 2-(N,N-diethylamino)diazenolate-2-oxide caused a fivefold rise in the levels of cyclic GMP, indicating operation of the glutamate-nitric oxide-cyclic GMP signaling pathway. Immunohistochemical mapping of Sepia CNS showed specific localization of nitric oxide synthase-like and NMDAR2/3-like immunoreactivities in the lateroventral palliovisceral lobe, the visceral lobe, and the pallial and visceral nerves, as well as in the sphincters and wall of the ink sac.

Animals↗

PubMed2006

Anterior segment growth and peripheral neural pathways in chick.

PURPOSE: To learn if peripheral nerve pathways are necessary for corneal expansion and anterior segment growth under a 12-hr light:dark cycle or for the inhibition of corneal expansion under constant light rearing. METHODS: Recently hatched White Leghorn chicks under anesthesia received unilateral ciliary ganglionectomy (CGx), cranial cervical ganglionectomy (Sx), or section of the ophthalmic nerve (TGx), along with sham-operated and/or never-operated control cohorts. Chicks were reared postoperatively under either a 12-hr light:dark cycle or under constant light. After 2 weeks and with the chicks under anesthesia, corneal radii of curvature and diameters were obtained with a photokeratoscope, refractometry and A-scan ultrasonography were performed, and the axial and equatorial dimensions of enucleated eyes were measured with digital calipers. Corneal areas were calculated from corneal curvatures and diameters. RESULTS: Despite the rich peripheral innervation to the eye, the selective denervations performed here exerted remarkably limited effects on corneal expansion and anterior segment development in chicks reared under either lighting condition. Ophthalmic nerve section did reverse in large part the inhibition of equatorial expansion of the vitreous chamber occurring under constant light rearing. CONCLUSIONS: The ciliary, sympathetic, or ophthalmic peripheral nerve pathways to the eye are not required either for corneal expansion and anterior segment development under a 12-hr light:dark cycle or for the inhibition of corneal expansion under constant light rearing. The ocular sensory innervation may be a means for regulating vitreous cavity shape.

Animals↗

PubMed1999

Opioids and food intake: distributed functional neural pathways?

Agonists of the mu, delta, kappa and ORL(1)opioid receptors increase food intake while opioid receptor blockade decreases food intake. The majority of the collected data related to opioids and feeding has led to the speculation that opioids are involved in meal maintenance and orosensory reward; however, some data suggest that opioids may impact feeding associated with energy needs. Based on the wide distribution of CNS opioid receptors and the presence of other neuropeptides in the vicinity of opioidergic pathways, it seems likely that opioids affect multiple feeding systems. For example, opioids in the hindbrain might be involved in both sensory and metabolic aspects of food intake, those in the amygdala in processing of 'emotional' properties of foods, and those in the hypothalamus in energy needs. In this review we present data which support functional diversity of opioids in feeding behavior.

Animals↗

PubMed1971

Neural pathways associated with hypothalamically elicited attach behavior in cats.

Small electrolytic lesions were made in cats through electrodes, which, when stimulated, elicited either quiet biting attack or affective paw strike attack upon rats. The Nauta method for impregnating degenerating axoplasm was used to reveal that degeneration resulting from lesions at quiet attack sites followed largely along the course of the medial forebrain bundle, while the degeneration after lesions of affective attack sites was concentrated more heavily in the periventricular system.

Aggression↗

PubMed1974

Neural pathways from thalamus associated with regulation of aggressive behavior.

Small electrolytic lesions were made through electrodes in the thalamus of cats at sites where electrical stimulation elicited attack on a rat. Staining by modified Nauta reduced silver methods revealed that significant degeneration passed caudally from the lesions and entered the midbrain dorsal central gray region. Electrical stimulation of this dorsal midbrain region elicited attack on a rat, and destruction of this region suppressed the attack elicited by thalamic stimulation.

Aggression↗

PubMed1975

Mapping of functional neural pathways by autoradiographic survey of local metabolic rate with (14C)deoxyglucose.

An enzymatic preparation from human brain converts tryptamine to tryptoline (9H-1,2,3,4-tetrahydropyrido(3,4-b)indole) in the presence of 5-methyltetrahydrofolic acid. Similarly, N-methyltryptamine and 5-hydroxytryptamine yield 1-methyltryptoline and 5-hydroxytryptoline, respectively. Neither in vitro nor in vivo formation of these compounds by human tissues has been described.

Animals↗

PubMed2004

Activation of neural pathways associated with sexual arousal in non-human primates.

PURPOSE: To evaluate brain activity associated with sexual arousal, fully conscious male marmoset monkeys were imaged during presentation of odors that naturally elicit high levels of sexual activity and sexual motivation. MATERIAL AND METHODS: Male monkeys were lightly anesthetized, secured in a head and body restrainer with a built-in birdcage resonator and positioned in a 9.4-Tesla spectrometer. When fully conscious, monkeys were presented with the odors of a novel receptive female or an ovariectomized monkey. Both odors were presented during an imaging trial and the presentation of odors was counterbalanced. Significant changes in both positive and negative BOLD signal were mapped and averaged. RESULTS: Periovulatory odors significantly increased positive BOLD signal in several cortical areas: the striatum, hippocampus, septum, periaqueductal gray, and cerebellum, in comparison with odors from ovariectomized monkeys. Conversely, negative BOLD signal was significantly increased in the temporal cortex, cingulate cortex, putamen, hippocampus, substantia nigra, medial preoptic area, and cerebellum with presentation of odors from ovariectomized marmosets as compared to periovulatory odors. A common neural circuit comprising the temporal and cingulate cortices, putamen, hippocampus, medial preoptic area, and cerebellum shared both the positive BOLD response to periovulatory odors and the negative BOLD response to odors of ovariectomized females. CONCLUSION: These data suggest the odor-driven enhancement and suppression of sexual arousal affect neuronal activity in many of the same general brain areas. These areas included not only those associated with sexual activity, but also areas involved in emotional processing and reward.

Animals↗

PubMed1985

Neural pathways mediating the corneal blink reflex and Bell's phenomenon in the cat.

Two central projections from the corneal representation of the sensory trigeminal complex in the cat were demonstrated with horseradish peroxidase, autoradiographic and Golgi methods: (1) to the dorsal subdivision of the ipsilateral facial nucleus that innervates the orbicularis oculi muscle; and (2) to the bordering area between the contralateral central gray matter and the oculomotor nucleus, which receives dendrites of the oculomotor cells innervating the contralateral superior rectus muscle. These two routes probably mediate early responses of the corneal blink reflex and Bell's phenomenon, respectively.

Animals↗

PubMed1997

PKA isoforms, neural pathways, and behaviour: making the connection.

In mammals, the cAMP-dependent protein kinase (PKA) family of enzymes is assembled from the products of four regulatory and two catalytic subunit genes, all of which are expressed in neurons. Specific isoforms of PKA display differences in biochemical properties and subcellular localization, but it has been difficult to ascribe specific physiological functions to any given isoform. The recent development of gene knockout and transgenic mouse models has allowed for a more integrated examination of the in vivo roles of specific PKA isoforms in gene expression, synaptic plasticity, and behaviour.

Animals↗

PubMed2000

Three novel neural pathways to the lacrimal glands of the cat: an investigation with cholera toxin B subunit as a retrograde tracer.

The distribution of ganglion neurons innervating the lacrimal gland (LG) was investigated following injection of cholera toxin B subunit into the LG of the cat. We report the first evidence that the otic ganglion (OG), and superior vagal and glossopharyngeal ganglia are also the sources of innervation of the LG. LG-innervating neurons in the pterygopalatine ganglion and the OG could be divided into two subpopulations: small and large neurons. They may mediate the vasodilatation and secretion, respectively.

Animals↗

PubMed2002

Neural pathways underlying vocal control.

Vocalization is a complex behaviour pattern, consisting of essentially three components: laryngeal activity, respiratory movements and supralaryngeal (articulatory) activity. The motoneurones controlling this behaviour are located in various nuclei in the pons (trigeminal motor nucleus), medulla (facial nucleus, nucl. ambiguus, hypoglossal nucleus) and ventral horn of the spinal cord (cervical, thoracic and lumbar region). Coordination of the different motoneurone pools is carried out by an extensive network comprising the ventrolateral parabrachial area, lateral pontine reticular formation, anterolateral and caudal medullary reticular formation, and the nucl. retroambiguus. This network has a direct access to the phonatory motoneurone pools and receives proprioceptive input from laryngeal, pulmonary and oral mechanoreceptors via the solitary tract nucleus and principal as well as spinal trigeminal nuclei. The motor-coordinating network needs a facilitatory input from the periaqueductal grey of the midbrain and laterally bordering tegmentum in order to be able to produce vocalizations. Voluntary control of vocalization, in contrast to completely innate vocal reactions, such as pain shrieking, needs the intactness of the forebrain. Voluntary control over the initiation and suppression of vocal utterances is carried out by the mediofrontal cortex (including anterior cingulate gyrus and supplementary as well as pre-supplementary motor area). Voluntary control over the acoustic structure of vocalizations is carried out by the motor cortex via pyramidal/corticobulbar as well as extrapyramidal pathways. The most important extrapyramidal pathway seems to be the connection motor cortex-putamen-substantia nigra-parvocellular reticular formation-phonatory motoneurones. The motor cortex depends upon a number of inputs for fulfilling its task. It needs a cerebellar input via the ventrolateral thalamus for allowing a smooth transition between consecutive vocal elements. It needs a proprioceptive input from the phonatory organs via nucl. ventralis posterior medialis thalami, somatosensory cortex and inferior parietal cortex. It needs an input from the ventral premotor and prefrontal cortex, including Broca's area, for motor planning of longer purposeful utterances. And it needs an input from the supplementary and pre-supplementary motor area which give rise to the motor commands executed by the motor cortex.

Animals↗

PubMed1982

Neural pathway involved in the excitation of motoneurones to jaw-opening muscles by stimulation of the orbital cerebral cortex in the cat.

The pathway and synaptic basis for the efferent discharge in the digastric nerve evoked by stimulation of the orbital cortex were studied in cats anesthetized with alpha-chloralose. Transection of the brain stem at the boundary between the pons and the medulla oblongata abolished discharge. Intracellular recording from anterior digastric motoneurones revealed that the orbital cortical stimulation evoked excitatory post-synaptic potentials with a latency that was longer by one synaptic delay than that of spike potentials evoked in medial bulbar reticular neurones making a direct excitatory projection to anterior digastric motoneurones. It was concluded that the excitatory effects was mediated by the medial bulbar reticular formation.

Animals↗

PubMed1984

Neural pathways mediating hypothalamically elicited flight behavior in the cat.

This study has sought to identify hypothalamic pathways mediating flight behavior in the cat. Flight behavior, characterized by an initial pupillary dilatation and followed by vigorous attempts to leap out of the observation chamber, was elicited primarily by electrical stimulation of the medial preoptic region and dorsomedial hypothalamus, and to a lesser extent from the perifornical region. A [14C]-2-deoxyglucose analysis was utilized to examine brain regions functionally activated by stimulation of hypothalamic sites which elicited flight behavior. In a second series of experiments, [3H]leucine injected into regions surrounding electrode tips from which flight had previously been elicited, permitted identification of pathways arising from such functionally characterized sites. We describe for the first time pathways arising from the hypothalamus which mediate flight behavior. In spite of individual variation in placement of electrodes eliciting flight, a consistent pattern of labeling was observed following injection of either [14C]-2-deoxyglucose systemically or [3H]amino acids into the hypothalamus. The primary rostral target structures receiving inputs from flight electrode sites included the nuclei of the diagonal band, bed nucleus of the stria terminalis, medial amygdaloid nucleus, lateral septal nucleus, and anterior medial preoptico-hypothalamus. Caudal to the level of stimulation, the principal target nuclei involved the centrum medianum-parafascicular complex and the midbrain central gray substance. Possible roles of these nuclear regions in organization and regulation of flight behavior is discussed.

Amygdala↗