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J A Narváez

Publications and source records attributed to J A Narváez.

At least 19 recordsLinked to original sources
PubMed2006

Region specific galanin receptor/neuropeptide Y Y1 receptor interactions in the tel- and diencephalon of the rat. Relevance for food consumption.

The aim of this work was to determine the interactions between NPY and GAL receptor (GALR) subtypes in the hypothalamus and the amygdala using quantitative receptor autoradiography to analyze the binding characteristics of NPY-Y1 and Y2 receptor subtypes in the presence and absence of GAL. Food intake in satiated animals was evaluated after intraventricular co-injections of GAL and NPY-Y1 or Y2 agonists. The expression of c-Fos IR in both regions was also investigated. GAL decreases NPY-Y1 agonist binding in the arcuate nucleus by about 15% (p<0.01), but increases NPY-Y1 agonist binding in amygdala (18%) (p<0.01). These effects were blocked with the GAL antagonist M35. Y2-agonist binding was not modified by GAL. GAL blocked the food intake induced by the Y1 agonist (p<0.01). Co-injections of Y1 agonist and GAL also reduced the c-Fos expression induced by the Y1 agonist in the arcuate nucleus and the dorsomedial hypothalamic nucleus but increased c-Fos expression in amygdala. These results indicate the existence of antagonistic interactions between GALR and NPY-Y1 receptors in the hypothalamus and their functional relevance for food intake. In contrast, a facilitatory interaction between GALR and Y1 receptors exists in the amygdala which may be of relevance for fear related behaviour.

Amygdala↗
PubMed2006

Receptor-receptor interactions in central cardiovascular regulation. Focus on neuropeptide/alpha(2)-adrenoreceptor interactions in the nucleus tractus solitarius.

The nucleus tractus solitarii (NTS) is a key nucleus in central cardiovascular control. In this mechanism it is well known the role of the alpha(2)-adrenoreceptors for the modulation of the autonomic pathways. Moreover a number of neuropeptides described in the NTS, including Neuropeptide Y (NPY), Galanin (GAL) and Angiotensin II (Ang II), have different roles in regulating the cardiovascular function within this nucleus. We show in this review several data which help to understand how these neuropeptides (NPY, GAL and Ang II) could modulate the cardiovascular responses mediated through alpha(2)-adrenoreceptors in the NTS. Also we show for the first time the interactions between neuropeptides in the brain, specifically the interactions between NPY, GAL, and Ang II, and its functional relevance for central cardiovascular regulation. These data strength the role of neuropeptides on central autonomic control and provide some evidences to understand the neurochemical mechanisms involved in the cardiovascular responses from the NTS.

Angiotensin II↗
PubMed2005

Giant cell arteritis and polymyalgia rheumatica: usefulness of vascular magnetic resonance imaging studies in the diagnosis of aortitis.

OBJECTIVES: One of the unresolved challenges posed in giant cell (temporal) arteritis (GCA) is the detection and monitoring of large-artery complications, particularly aortitis. Recent investigations support vascular magnetic resonance imaging (MRI) studies in this issue. We report our preliminary experience with this imaging technique in the study of the aorta and its proximal branches in patients with GCA and/or polymyalgia rheumatica (PMR). METHODS: Between 2000 and 2003, six patients with GCA and/or PMR seen in our department were diagnosed with aortitis using vascular MRI studies. In all cases, the study was performed according to a specifically designed protocol that included MRI and MR angiography (MRA). RESULTS: MRI was a hepful non-invasive method for diagnosis of aortitis in all cases, providing accurate information about its extent. In particular, MRI had a higher ability to detect earlier stages of vasculitis disclosing subclinical aortitis in five of the six patients. The main signs of early vascular inflammation observed were vessel wall thickness and oedema (six cases) and increased mural enhancement on postcontrast T1-weighted images (four cases). MRA disclosed lumen changes (stenosis) in two patients. On follow-up studies, whereas vascular stenosis and vessel wall thickness remained invariable, vascular wall oedema and contrast enhancement improved significantly when disease activity decreased. CONCLUSION: MRI may be a useful technique for diagnosing patients with occult major artery involvement in GCA, whether presenting with classic symptoms of temporal arteritis or PMR. Its utility for monitoring the course of the disease and response to treatment requires further confirmation.

Aged↗
PubMed2005

Role of galanin and galanin(1-15) on central cardiovascular control.

Galanin and the N-terminal fragment Galanin(1-15) are involved in central cardiovascular regulation. The present paper reviews the recent cardiovascular results obtained by intracisternal injections of Galanin and Galanin(1-15) showing that: (A) the Galanin antagonist M40 blocks the central cardiovascular responses induced by Galanin(1-15) but not those elicited by Galanin; (B) both Galanin and Galanin(1-15) induce the expression of c-Fos in cardiovascular nuclei of the medulla oblongata with different temporal and spatial profiles; (C) the cardiovascular action of Galanin(1-15), but not Galanin, is mediated by peripheral beta-receptor stimulation; (D) and it is demonstrated an antagonistic Galanin/alpha2-adrenoceptors interaction as well as a differential modulation of central cardiovascular responses of Angiotensin II by Galanin or Galanin(1-15). All these data strengthen the involvement of both Galanin molecules as neuromodulators on central cardiovascular regulation.

Animals↗
PubMed2005

Mapping of tachykinins in the cat spinal cord.

Using an indirect immunoperoxidase technique, the location of cell bodies and fibers containing substance P, neurokinin A and neurokinin B was studied in the cat spinal cord. The former two neuropeptides showed a widespread distribution throughout the whole spinal cord, whereas the distribution of neurokinin B was more restricted. Neurokinin A-immunoreactive structures showed a more widespread distribution and a higher density than the immunoreactive structures observed to contain substance P. In the cat spinal cord, we observed cell bodies containing neurokinin A, but no cell bodies containing neurokinin B or substance P were found. These cell bodies were located in laminae V (sacral 1 and 2 levels), VI (sacral 1 and 3), VII (lumbar 7, sacral 1 and 3, caudal 1) and X (sacral 1). Laminae I and II showed the highest density of immunoreactive fibers for each of the three tachykinins studied, being in general lamina IV who showed the lowest number of immunoreactive fibers containing substance P, neurokinin A or B. The anatomical distribution of the three tachykinins studied in the cat spinal cord indicates that the neuropeptides could be involved in the neurotransmission and/or in the neuromodulation of nociceptive information, as well as in autonomic and affective responses to pain. Moreover, the involvement of substance P, neurokinin A or B in other functions unrelated to the transmission of pain is also possible (autonomic and motor functions). The distribution of the neuropeptides studied in the cat is compared with the location of the same neuropeptides in the spinal cord of other species. The possible origin of the tachykinergic fibers in the cat spinal cord is also discussed.

Animals↗
PubMed2004

Subperiosteal leiomyosarcoma of the tibia.

Primary leiomyosarcoma of bone is a rare malignant tumor of smooth muscle. We report a case of low-grade subperiosteal primary bone leiomyosarcoma in the tibial diaphysis, which radiologically appeared to be osteoid osteoma. A 35-year-old man presented with a several-year history of a palpable hard nodule in the distal left leg, which had enlarged and become painful over the previous 2 years. Radiographs showed solid periosteal reaction with a well-defined lytic lesion in the posteromedial cortical border of the left tibial diaphysis. Computed tomography demonstrated a small, well-defined lytic lesion, not calcified, in a subperiosteal location, surrounded by solid periosteal bone formation. The lesion was excised en bloc and the histological diagnosis of a low-grade leiomyosarcoma was made. To the best of our knowledge, the surface location of primary bone leiomyosarcoma has not been previously described in the literature.

Adult↗
PubMed2004

An immunocytochemical mapping of methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem.

Using an indirect immunoperoxidase technique, we studied the distribution of immunoreactive fibers and cell bodies containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the adult human brainstem. Immunoreactive cell bodies were found in the reticular formation of the medulla oblongata (in which we observed the highest density of immunoreactive cell bodies) and the pons, the solitary nucleus, the hypoglossal nucleus, the medial and spinal vestibular nuclei, the lateral cuneate nucleus, the nucleus prepositus, the central gray of the pons and mesencephalon, the central and pericentral nuclei of the inferior colliculus, the superior colliculus, ventral to the superior olive and in the midline region of the pons and mesencephalon. The highest density of immunoreactive fibers containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) was found in the spinal trigeminal nucleus, the central gray and the reticular formation of the medulla oblongata, pons and mesencephalon, the solitary nucleus, the spinal vestibular nucleus, the dorsal accessory olivary nucleus, the raphe obscurus, the substantia nigra and in the interpeduncular nucleus. The widespread distribution of immunoreactive structures containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem indicates that this neuropeptide might be involved in several physiological mechanisms, acting as a neurotransmitter and/or neuromodulator.

Aged↗
PubMed2004

Long-term modulation by postnatal oxytocin of the alpha 2-adrenoceptor agonist binding sites in central autonomic regions and the role of prenatal stress.

The aim of this work was to evaluate whether oxytocin administered in male rats subcutaneously early in life in the absence or presence of food restriction during pregnancy has life-long effects on the alpha(2)-agonist binding sites in the nucleus of the solitarii tract (NTS), in the hypothalamus and the amygdala, as evaluated by quantitative receptor autoradiography. Maternal food restriction alone increased the affinity of the alpha(2)-agonist [(3)H]UK14.304 binding sites exclusively in the NTS. In offspring from ad libitum fed dams, oxytocin treatment significantly increased the density of alpha(2)-agonist binding sites in the NTS and in the hypothalamus. The K(d) value of the alpha(2)-agonist binding sites in the hypothalamus of these rats, but not in the other regions studied, was also significantly increased. In offspring from food-restricted dams, oxytocin treatment produced a significant increase of the B(max) values in the hypothalamus and the amygdala and the K(d) value of the alpha(2)-agonist binding sites in the NTS of these rats also was selectively and significantly increased. These results suggest that a postnatal, oxytocin-induced increase of regional alpha(2)-adrenoceptor function can be seen in adulthood by a persistent, regionally selective increase in the density of central alpha(2)-adrenoceptor agonist binding sites, in the absence of an affinity change in the NTS. Such a regional increase of alpha(2)-adrenoceptor signalling in adulthood may contribute to the anti-stress action of postnatal oxytocin. By contrast, after prenatal stress, the potential increase in alpha(2)-adrenoceptor signalling takes place via selective increases of density with no changes of affinity of the alpha(2)-agonist binding sites in the hypothalamus and the amygdala.

Adrenergic alpha-2 Receptor Agonists↗
PubMed2003

An immunocytochemical mapping of somatostatin in the cat auditory cortex.

Using an indirect immunoperoxidase technique, the localization of somatostatin-28 (1-12)-like immunoreactive fibers and cell bodies in the auditory cortex of the cat (anterior, primary, secondary, temporal, ventral, ventroposterior, posterior and dorsoposterior auditory fields) was studied. In general, the distribution of SOM-ir structures is widespread in the auditory cortex of the feline. A high density of immunoreactive fibers as well as a low density of cell bodies containing somatostatin were observed in all the layers of the eight above-mentioned auditory fields. These data indicate that somatostatin-28 (1-12) could act as a neurotransmitter and/or a neuromodulator in the auditory cortex of the cat. The origin of the SOM-ir fibers in the auditory cortex of the cat, as well as the issue of whether the cell bodies containing somatostatin-28 (1-12) are local or projecting neurons is discussed.

Animals↗
PubMed2002

Spontaneous osteonecrosis of the knee associated with tibial plateau and femoral condyle insufficiency stress fracture.

The purpose of this article is to describe the association between spontaneous osteonecrosis and insufficiency stress fractures of the knee. To determine whether insufficiency stress fracture is associated with spontaneous osteonecrosis of the knee, we retrospectively reviewed the medical charts and imaging studies of all patients with spontaneous osteonecrosis of the knee, studied by MR imaging, seen in a tertiary hospital over an 8-year period. Four women (age range 66-84 years) presented spontaneous osteonecrosis of the knee associated with insufficiency stress fracture of the medial tibial plateau. One of these patients also presented a concomitant insufficiency stress fracture of the medial femoral condyle. Radiographs were diagnostic of spontaneous osteonecrosis of the medial femoral condyle in three cases, and insufficiency stress fracture of the medial tibial plateau was detected in one case. Magnetic resonance imaging allows the diagnosis of both conditions in all four cases. Spontaneous osteonecrosis of the knee may be associated with insufficiency stress fracture of the medial femoral condyle and the medial tibial plateau. This association provides additional arguments in favor of the traumatic etiology of spontaneous osteonecrosis of knee.

Aged↗
PubMed2001

MR imaging of synovial tumors and tumor-like lesions.

The clinical diagnosis of synovial tumors and tumorlike lesions is difficult, and radiographic findings may establish a confident diagnosis only in some cases. MR imaging has become the modality of choice in evaluating these lesions, because with it a presumptive diagnosis can be made in most cases. Our goal is to review the MR features of pigmented villonodular synovitis, giant-cell tumor of the tendon sheath, synovial chondromatosis, synovial hemangioma, lipoma arborescens, synovial cysts and synovial sarcoma, emphasizing those findings that suggest a specific diagnosis.

Adolescent↗
PubMed2001

Galanin/alpha2-adrenoceptor interactions in telencephalic and diencephalic regions of the rat.

The aim of this study was to evaluate whether galanin could affect central alpha2-adrenoceptors in telencephalic and diencephalic regions in the rat using quantitative receptor autoradiography with the alpha2 agonist radioligand [3H]p-aminoclonidine. Galanin 1 nM significantly and substantially increased the Kd value of the [3H]p-aminoclonidine binding sites in the medial hypothalamus and amygdala by 86% (p < 0.01) and 73% (p < 0.05) respectively. The Bmax value was only significantly increased with 3 nM galanin in the amygdala and the medial hypothalamus (both p < 0.05). The antagonist M35 counteracted the increase of the Kd values of the alpha2-adrenoceptor agonist binding sites produced by galanin 1 nM in the amygdala and the medial hypothalamus (both p < 0.001). These findings suggest the existence of an antagonistic galanin/alpha2 adrenoceptor interaction in the medial hypothalamus and amygdala that may be of relevance for alpha2-adrenoceptor-regulated neuroendocrine functions and food intake.

Adrenergic alpha-Agonists↗
PubMed2001

Central galanin and N-terminal galanin fragment induce c-Fos immunoreactivity in the medulla oblongata of the anesthetized rat.

This immunohistochemical study analyzed the c-Fos expression (c-Fos-ir) induced by galanin injections. Galanin and N-terminal galanin fragment (1-15) induced a significant increase of c-Fos expression (c-ir) within the medulla oblongata 90 min and 6 h. after intracisternal injections. This expression has been studied mainly in the nucleus of the solitary tract and in the ventrolateral medulla showing different temporal profiles for both peptides. The presence of c-Fos-ir in TH-positive cells was analyzed in all the groups. These results may be relevant to understand the role of galanin in several functions including central cardiovascular control.

Animals↗
PubMed2001

Depletion of substance P, neurokinin A and calcitonin gene-related peptide from the contralateral and ipsilateral caudal trigeminal nucleus following unilateral electrical stimulation of the trigeminal ganglion; a possible neurophysiological and neuroanatomical link to generalized head pain.

Primary trigeminal neurons of the trigeminal ganglion (TG) innervate major parts of the face and head, including the dura. Electrical stimulation of the TG at specific parameters, can activate its nociceptive neurons and may serve as an experimental pain model. Markowitz [J. Neurosci. 7 (1987) 4129] reported that electrical stimulation of the trigeminal ganglion (TG) causes extravasation of plasma proteins from venules of the trigeminally innervated domain possibly due to the release of vasoactive substances. Neurogenic inflammation (vasodilatation, plasma protein extravasation, release of vasoactive peptides) in dura may serve as one of the possible pathomechanisms underlying vascular head pain [Moskowitz, Ann. Neurol. 16 (1984) 157]. We performed a unilateral electrical stimulation (7.5 Hz, 5 ms, 0.8-1.4 mA for 5 min) of the TG in rat, to induce a neurogenic inflammation in the peripheral trigeminal domain including the dura, looking for calcitonin gene related peptide (CGRP), substance P (SP) and neurokinin A (NKA) immunoreactivity (IR) in the caudal trigeminal nucleus (CTN) into which massive central trigeminal processes terminate. Here, we show patchy depletion(s) of CGRP-, SP- and NKA-IRs in the contralateral CTN of the rat in addition to their ipsilateral depletion. Such depletion is due to the release of these neuropeptides in the CTN leading to the activation of bilateral trigeminal nociceptive pathway. These data afford the possibility that under specific frequencies (which may roughly correlate to the intensity of the painful stimulus) and/or specific intensities (may correlate to specific areas of the peripheral trigeminal domain) of stimulation, activation of one side of the TG may activate bilateral trigeminal nociceptive pathway leading to the perception of an ill localized/generalized pain or headache rather than a unilateral one.

Animals↗
PubMed2001

Musculoskeletal manifestations in polymyalgia rheumatica and temporal arteritis.

OBJECTIVE: To evaluate the incidence and characteristics of musculoskeletal manifestations in polymyalgia rheumatica (PMR) and temporal arteritis (TA). METHODS: The records of 163 cases of PMR or TA diagnosed over a 15 year period in one area of Spain were reviewed for the presence and type of musculoskeletal manifestations. RESULTS: Of 163 patients, 90 had isolated PMR and 73 had TA. Eighteen of the 90 patients (20%) with isolated PMR developed distal peripheral arthritis either at diagnosis or during the course of the disease. When it occurred, synovitis was mild, monoarticular or pauci-articular, asymmetrical, transient, and not destructive. Other distal manifestations observed in these patients were carpal tunnel syndrome and distal extremity swelling with pitting oedema. In all cases these manifestations occurred in conjunction with active PMR. As expected, PMR was the most frequent musculoskeletal manifestation in patients with TA, occurring in 56% of cases. On the contrary, only 11% of patients with TA developed peripheral arthritis. An important finding was that peripheral arthritis in these patients appears to be linked only temporally to the presence of simultaneous PMR and is not observed in its absence. Distal extremity swelling or defined polyarthritis were not observed. CONCLUSION: The spectrum of distal musculoskeletal manifestations of PMR in our series is similar to that reported in other populations. By contrast, distal musculoskeletal symptoms are uncommon in TA. The almost complete absence of distal musculoskeletal manifestations in patients with pure TA suggests different mechanisms of disease in PMR and TA, supporting the view of two separate conditions or one common disease in which host susceptibility influences the clinical expression.

Aged↗
PubMed2000

Systemic oxytocin treatment modulates alpha 2-adrenoceptors in telencephalic and diencephalic regions of the rat.

Systemic subchronic oxytocin treatment significantly and substantially increased the B(max) values of the alpha 2 agonist [(3)H]UK14.304 binding sites in the hypothalamus, the amygdala and the paraventricular thalamic nucleus of the rat as shown by quantitative receptor autoradiography. These results suggest that long-term modulation of autonomic and neuroendocrine functions and emotional behaviours elicited by brain oxytocin may involve enhancement of central alpha 2-adrenoceptor function.

Adrenergic alpha-Agonists↗
PubMed2000

The galanin receptor antagonist M40 blocks the central cardiovascular actions of the galanin N-terminal fragment (1-15).

It has been shown that galanin plays a role in central cardiovascular regulation. Galanin administered centrally induces an increase of heart rate and a weak vasodepressor response, whereas the N-terminal galanin fragment (1-15) elicits vasopressor effects and tachycardia. Furthermore, it has been shown that galanin-(1-15), but not galanin-(1-29), decreases the baroreceptor reflex sensitivity. Since these data demonstrate that both galanin and its N-terminal fragment (1-15) exert a different modulation on central cardiovascular control, the aim of this work has been to study if the specific galanin receptor antagonist Galanin-(1-12)-Pro-(Ala-Leu)(2)-Ala]-amide (M40) could modulate their cardiovascular actions. Urethane anaesthetized rats were injected intracisternally and the changes in mean arterial pressure and heart rate were monitored. Two doses of M40 alone have been tested for their cardiovascular effects. With the dose of 1.0 nmol, a significant tachycardia was observed (P<0.001), but 0.1 nmol was ineffective. This suggests a possible agonistic effect for the higher doses of M40. The galanin receptor antagonist M40 at the dose of 0.1 nmol failed to modify the weak vasodepressor effects and tachycardia induced by 3.0 nmol of galanin-(1-29). However, the same dose completely blocked the vasopressor and tachycardic responses elicited by 3.0 nmol of galanin-(1-15). These data show that M40 differentially counteracts the central cardiovascular responses of the galanin fragment and give a functional support for the existence of galanin receptor subtypes within the brainstem. Therefore, the present findings can be explained on the basis that the cardiovascular actions of galanin-(1-29) could be mediated by one type of galanin receptor, whereas a galanin receptor subtype that recognizes N-terminal fragments of galanin may mediate the actions of galanin-(1-15).

Animals↗