Telemedicina en cirugía vascular y endovascular: experiencia en un centro universitario / Analysis of the first 106 telemedicine consultations in a vascular surgery service

BACKGROUND: Telemedicine became a relevant means to provide healthcare without face-to-face medical evaluation during the COVID-19 pandemic. AIM: To describe the effectiveness of telemedicine in vascular surgery. Materials and Methods: Review of medical records of all vascular surgery consultations carried out in a clinical hospital between April and October 2020. The main outcome measured was the resolution of the reason for consultation. Secondary outcomes were the need to request laboratory tests or imaging, the need to evaluate the patient in person, and the need for referral to hospitalization or emergency service. RESULTS: One hundred-six new consultations and their follow-up (remotely or in person) were analyzed. A definitive diagnosis could be reached in 74% of consultations, treatment could be instituted or modified in 69% of them, and the reason for consultation could be resolved in 74% of cases. Laboratory and imaging tests were requested in 36 and 63% of consultations, respectively. Four percent of patients were referred to the emergency department or hospitalization. Conclusions: In the vast majority of consultations, it was possible to achieve a definitive diagnosis, prescribe a treatment and resolve the reason for consultation without the need for a face-to-face medical evaluation.

[Analysis of the first 106 telemedicine consultations in a vascular surgery service]. / Telemedicina en cirugía vascular y endovascular: experiencia en un centro universitario.

BACKGROUND: Telemedicine became a relevant means to provide healthcare without face-to-face medical evaluation during the COVID-19 pandemic. AIM: To describe the effectiveness of telemedicine in vascular surgery. MATERIALS AND METHODS: Review of medical records of all vascular surgery consultations carried out in a clinical hospital between April and October 2020. The main outcome measured was the resolution of the reason for consultation. Secondary outcomes were the need to request laboratory tests or imaging, the need to evaluate the patient in person, and the need for referral to hospitalization or emergency service. RESULTS: One hundred-six new consultations and their follow-up (remotely or in person) were analyzed. A definitive diagnosis could be reached in 74% of consultations, treatment could be instituted or modified in 69% of them, and the reason for consultation could be resolved in 74% of cases. Laboratory and imaging tests were requested in 36 and 63% of consultations, respectively. Four percent of patients were referred to the emergency department or hospitalization. CONCLUSIONS: In the vast majority of consultations, it was possible to achieve a definitive diagnosis, prescribe a treatment and resolve the reason for consultation without the need for a face-to-face medical evaluation.

Cirugía convencional del aneurisma tóraco-abdominal / Open surgical treatment of thoracoabdominal aortic aneurysm. Experience in 45 patients

BACKGROUND: Thoracoabdominal aortic aneurysm (TAAA) is an infrequent disease and demands a highly specialized and experienced management. Open repair (OR) is the gold standard but it is associated with significant morbidity and mortality. Paraplegia and renal failure are the most important complications. AIM: To report our results with OR treatment of TAAA. MATERIAL AND METHODS: Descriptive study including all patients with TAAA operated electively and consecutively by OR between 1983 and 2019. Main outcomes are operative mortality, renal and neurological morbidity, and long-term survival. RESULTS: We report 45 operated patients aged 33 to 84 years, 74% males. Aneurysm extension according to Crawford classification was I in 18%, II in 18 %, III in 36% and IV in 29%. Operative mortality was 4%. The frequency of paraplegia or paraparesis at discharge was 9%. No patient was discharged on hemodialysis. Survival at 5 and 10 years were 60% and 40% respectively. CONCLUSIONS: OR of TAAA is a complex procedure. Our results show perioperative mortality rates comparable to highly experienced centers. Although being a major procedure, OR remains an alternative to treat this serious condition.

[Open surgical treatment of thoracoabdominal aortic aneurysm. Experience in 45 patients]. / Cirugía convencional del aneurisma tóraco-abdominal.

BACKGROUND: Thoracoabdominal aortic aneurysm (TAAA) is an infrequent disease and demands a highly specialized and experienced management. Open repair (OR) is the gold standard but it is associated with significant morbidity and mortality. Paraplegia and renal failure are the most important complications. AIM: To report our results with OR treatment of TAAA. MATERIAL AND METHODS: Descriptive study including all patients with TAAA operated electively and consecutively by OR between 1983 and 2019. Main outcomes are operative mortality, renal and neurological morbidity, and long-term survival. RESULTS: We report 45 operated patients aged 33 to 84 years, 74% males. Aneurysm extension according to Crawford classification was I in 18%, II in 18 %, III in 36% and IV in 29%. Operative mortality was 4%. The frequency of paraplegia or paraparesis at discharge was 9%. No patient was discharged on hemodialysis. Survival at 5 and 10 years were 60% and 40% respectively. CONCLUSIONS: OR of TAAA is a complex procedure. Our results show perioperative mortality rates comparable to highly experienced centers. Although being a major procedure, OR remains an alternative to treat this serious condition.

Isquemia de extremidades inferiores secundaria a arteritis de la arteria temporal

Giant cell arteritis is more common in women older than 60 years, is associated with systemic inflammation symptoms and mainly involves the aortic arch and cranial arteries, specially the temporal artery. Symptomatic lower extremity arterial stenosis or occlusion is uncommon and can lead to limb loss. We report a 73-year-old woman presenting with a one-month history of lower extremity intermittent claudication of sudden onset. She also complained of fever, malaise, headache and weight loss. A non-invasive vascular study showed moderate femoral popliteal occlusive disease, with and abnormal ankle-brachial index (0.68 and 0.83 on right and left sides, respectively). An angio-computed tomography showed thickening of the aortic wall and severe stenosis in both superficial femoral arteries. Steroidal treatment was started, and a temporal artery biopsy was performed confirming giant cell arteritis. Six weeks after steroid therapy the patient had a complete remission of symptoms. A serologic exacerbation was subsequently treated with a humanized monoclonal antibody against the interleukin-6 receptor Tocilizumab, obtaining long time remission.

[Lower limb ischemia in giant cell arteritis. Report of one case]. / Isquemia de extremidades inferiores secundaria a arteritis de la arteria temporal.

Giant cell arteritis is more common in women older than 60 years, is associated with systemic inflammation symptoms and mainly involves the aortic arch and cranial arteries, specially the temporal artery. Symptomatic lower extremity arterial stenosis or occlusion is uncommon and can lead to limb loss. We report a 73-year-old woman presenting with a one-month history of lower extremity intermittent claudication of sudden onset. She also complained of fever, malaise, headache and weight loss. A non-invasive vascular study showed moderate femoral popliteal occlusive disease, with and abnormal ankle-brachial index (0.68 and 0.83 on right and left sides, respectively). An angio-computed tomography showed thickening of the aortic wall and severe stenosis in both superficial femoral arteries. Steroidal treatment was started, and a temporal artery biopsy was performed confirming giant cell arteritis. Six weeks after steroid therapy the patient had a complete remission of symptoms. A serologic exacerbation was subsequently treated with a humanized monoclonal antibody against the interleukin-6 receptor Tocilizumab, obtaining long time remission.

Long-lasting, reversible and non-neurotoxic inactivation of hippocampus activity induced by neosaxitoxin.

BACKGROUND: Neosaxitoxin (NeoSTX) and related paralytics shellfish toxins has been successfully used as local anesthetic and muscle relaxants to treat a variety of ailments. The primary mechanism of action of these toxins occurs by blocking voltage-gated sodium channels with compounds such as TTX, lidocaine, or derivatives. However, most of these non-classical sodium channel blockers act with a reduced time effect as well as ensuing neurotoxicity. NEW METHOD: In this report, we show that the use of local NeoSTX injections inactivates the hippocampal neuronal activity reversibly with a by long-term dynamics, without neuronal damage. RESULTS: A single 10 ng/µl injection of NeoSTX in the dorsal CA1 region abolished for up to 48 h memory capacities and neuronal activity measured by the neuronal marker c-fos. After 72 h of toxin injection, the animals fully recover their memory capacities and hippocampal neuronal activity. The histological inspection of NeoSTX injected brain regions revealed no damage to the tissue or reactive gliosis, similar to vehicle injection. Acute electrophysiological recording in vivo shows, also, minimal spreading of the NeoSTX in the cerebral tissue. COMPARISON WITH EXISTING METHODS: Intracerebral NeoSTX injection showed longer effects than other voltage sodium channel blocker, with minimal spreading and no neuronal damage. CONCLUSION: NeoSTX is a new useful tool that reversibly inactivates different brains region for a long time, with minimal diffusion and without neuronal damage. Moreover, NeoSTX can be used as a valuable sodium channel blocker for many studies in vivo and with potential therapeutic uses.

Infralimbic cortex controls core body temperature in a histamine dependent manner.

An increase in body temperature accelerates biochemical reactions and behavioral and physiological responses. A mechanism to actively increase body temperature would be beneficial during motivated behaviors. The prefrontal cortex is implicated in organizing motivated behavior; the infralimbic cortex, a subregion of the medial prefrontal cortex, has the necessary connectivity to serve the role of initiating such thermogenic mechanism at the beginning of the appetitive phase of motivated behavior; further, this cortex is active during motivated behavior and its disinhibition produces a marked behavioral and vegetative arousal increase, together with increases in histamine levels. We wanted to explore if this arousal was related to histaminergic activation after pharmacological infralimbic disinhibition and during the appetitive phase of motivated behavior. We measured core temperature and motor activity in response to picrotoxin injection in the infralimbic cortex, as well as during food-related appetitive behavior, evoked by enticing hungry rats with food. Pretreatment with the H1 receptor antagonist pyrilamine decreased thermal response to picrotoxin and enticement and completely blunted motor response to enticement. Motor and temperature responses to enticement were also completely abolished by infralimbic cortex inhibition with muscimol. To assess if this histamine dependent temperature increase was produced by an active sympathetic mediated thermogenic mechanism or was just a consequence of increased locomotor activity, we injected propranolol (i.p.), a ß adrenergic receptor blocker, before picrotoxin injection into the infralimbic cortex. Propranolol reduced the temperature increase without affecting locomotor activity. Altogether, these results suggest that infralimbic activation is necessary for appetitive behavior by inducing a motor and a vegetative arousal increase mediated by central histamine.

Hemangioma cavernoso rectal: caso clínico / Cavernous hemangioma of the rectum: report of one case

We report a 41 years old male with a history of hematochezia since childhood. A colonoscopy showed a highly vascularized submucosal lesion extending from the pectinate line to the distal sigmoid colon. Magnetic resonance showed a thickening of rectal wall with multiple vascular structures and phleboliths. The lesion was excised surgically. The postoperative period was uneventful. The pathological report disclosed a large rectal hemangioma.

El hemangioma rectal es una entidad infrecuente, con menos de 200 casos publicados en la literatura mundial. Se presenta un caso clínico, que debuta con rectorragia y es documentado con estudios endoscópicos e imagenológicos, siendo resuelto quirúrgicamente.

[The negative side of emotions: addiction to drugs of abuse]. / El lado negativo de las emociones: la adicción a drogas de abuso.

INTRODUCTION: According to the model of emotions, feelings have their origin in the conscious perception of body changes produced in response to an emotional stimulus. These changes are perceived thanks to the fact that they are represented in the brain by the interoceptive system. During abstinence, addicts experience intense feelings of ill-being that drive them to consume drugs. The purpose of this review is to discuss the role played by the interoceptive system, and more especially the insular cortex, in the perception of the negative feelings that characterise abstinence. DEVELOPMENT: The continuous processing of interoceptive signals in the insular cortex is what accounts for the conscious appreciation of the body changes that accompany an emotional state. Temporary inactivation of the insular cortex suppresses the search for drugs in addicted rats. Neuroimaging studies reveal an increase in the neuronal activity in the insular cortex and in other areas of the brain while addicts are experiencing the craving to consume drugs. Likewise, nicotine addicts who suffer a brain injury that affects the insular cortex give up smoking easily because they lose the desire to do it. The temporary suppression of neuronal activity in the insular cortex in human addicts by means of non-invasive techniques could be a new therapy to treat the craving to consume drugs. CONCLUSIONS: The insular cortex is essential in the perception of the emotional states and in orienting behaviour to match the needs of the body. New therapies that have the insular cortex as their target could be developed to mitigate craving.

El lado negativo de las emociones: la adicción a drogas de abuso / The negative side of emotions: Addiction to drugs of abuse

Introducción. El modelo de emociones plantea que los sentimientos se originan en la percepción consciente de los cambios corporales producidos en respuesta a un estímulo emocional. Estos cambios son percibidos gracias a que se representan en el cerebro por el sistema interoceptivo. Durante la abstinencia, los adictos experimentan intensos sentimientos de malestar que motivan el consumo de drogas. El propósito de esta revisión es comentar el rol del sistema interoceptivo, en particular de la ínsula, en la percepción de sentimientos negativos característicos de la abstinencia. Desarrollo. El procesamiento continuo de señales interoceptivas en la ínsula subyace a la apreciación consciente de los cambios corporales que acompañanun estado emocional. La inactivación transitoria de la corteza insular suprime la búsqueda de droga en ratas adictas. Estudios de neuroimágenes revelan un aumento de la actividad neuronal de la ínsula y de otras regiones cerebrales mientras los adictos experimentan el deseo compulsivo de consumir drogas. Asimismo, los adictos a la nicotina que sufren una lesión cerebral que afecta la ínsula dejan de fumar fácilmente porque pierden el deseo de hacerlo. La supresión transitoria de la actividadneuronal de la ínsula en humanos adictos a través de técnicas no invasivas podría ser una nueva terapia para el deseo compulsivo de consumir drogas. Conclusiones. La ínsula es esencial en la percepción de los estados emocionales y en la orientación de la conducta de una manera acorde con las necesidades del cuerpo. Podrían desarrollarse nuevas terapias paraaliviar el deseo compulsivo utilizando como blanco la corteza insular

According to the model of emotions, feelings have their origin in the conscious perception of bodychanges produced in response to an emotional stimulus. These changes are perceived thanks to the fact that they are represented in the brain by the interoceptive system. During abstinence, addicts experience intense feelings of ill-being that drive them to consume drugs. The purpose of this review is to discuss the role played by the interoceptive system, and more especiallythe insular cortex, in the perception of the negative feelings that characterise abstinence. Development. The continuousprocessing of interoceptive signals in the insular cortex is what accounts for the conscious appreciation of the body changes that accompany an emotional state. Temporary inactivation of the insular cortex suppresses the search for drugs in addicted rats. Neuroimaging studies reveal an increase in the neuronal activity in the insular cortex and in other areas of the brainwhile addicts are experiencing the craving to consume drugs. Likewise, nicotine addicts who suffer a brain injury that affects the insular cortex give up smoking easily because they lose the desire to do it. The temporary suppression of neuronal activity in the insular cortex in human addicts by means of non-invasive techniques could be a new therapy to treat the craving toconsume drugs. Conclusions. The insular cortex is essential in the perception of the emotional states and in orienting behaviour to match the needs of the body. New therapies that have the insular cortex as their target could be developed to mitigate craving

Clock gene expression in adult primate suprachiasmatic nuclei and adrenal: is the adrenal a peripheral clock responsive to melatonin?

The circadian production of glucocorticoids involves the concerted action of several factors that eventually allow an adequate adaptation to the environment. Circadian rhythms are controlled by the circadian timing system that comprises peripheral oscillators and a central rhythm generator located in the suprachiasmatic nucleus (SCN) of the hypothalamus, driven by the self-regulatory interaction of a set of proteins encoded by genes named clock genes. Here we describe the phase relationship between the SCN and adrenal gland for the expression of selected core clock transcripts (Per-2, Bmal-1) in the adult capuchin monkey, a New World, diurnal nonhuman primate. In the SCN we found a higher expression of Bmal-1 during the h of darkness (2000-0200 h) and Per-2 during daytime h (1400 h). The adrenal gland expressed clock genes in oscillatory fashion, with higher values for Bmal-1 during the day (1400-2000 h), whereas Per-2 was higher at nighttime (about 0200 h), resulting in a 9- to 12-h antiphase pattern. In the adrenal gland, the oscillation of clock genes was accompanied by rhythmic expression of a functional output, the steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase. Furthermore, we show that adrenal explants maintained oscillatory expression of Per-2 and Bmal-1 for at least 36 h in culture. The acrophase of both transcripts, but not its overall expression along the incubation, was blunted by 100 nm melatonin. Altogether, these results demonstrate oscillation of clock genes in the SCN and adrenal gland of a diurnal primate and support an oscillation of clock genes in the adrenal gland that may be modulated by the neurohormone melatonin.

Sobrevida del cáncer vesical infiltrante: experiencia Hospital Sótero del Río / Survival of muscle-invasive bladder carcinoma: experience of Hospital Sotero del Rio

Objetivo: Análisis de la sobrevida y de los factores que influyen en el pronóstico del cáncer vesical infiltrante. Material y métodos: Se realiza un estudio retrospectivo de pacientes con el diagnóstico de cáncer vesical infiltrante sometidos a cirugía entre los años 1996-2006. Se realiza un análisis de sobrevida mediante Método de Kaplan-Meier y se analizan las variables que influyen en el pronóstico. Resultados: La serie consta de 78 pacientes que ingresaron al Servicio de Urología y que presentaron cáncer vesical infiltrante. La edad promedio es de 69,11 años, siendo el 65,38 por ciento de los pacientes (51) de sexo masculino. El tipo histológico predominante fue Carcinoma de Células Transicionales (69,2 por ciento).De los 78 pacientes de la serie, el 52,5 por ciento (41) fue sometido a cistectomía radical. El resto sólo tuvo procedimientos de carácter paliativo para control local de la enfermedad. Respecto de la presentación según etapas (clasificación TNM-AJCC), el 40 por ciento de los pacientes se presentó en etapa II, 20 por ciento en etapa III y un 40 por ciento en etapa IV. El seguimiento promedio fue de 22,1 meses. La sobrevida cáncer específica estimada según Kaplan- Meier fue de 54,3 por ciento, 34,6 por ciento, 25,9 por ciento a 1, 3 y 5 años respectivamente. El factor más importante que se correlaciona con la sobrevida fue la etapa de presentación. Conclusión: En nuestra serie el cáncer vesical infiltrante se presenta en etapas avanzadas (etapa IIIy IV) lo que limita las posibilidades de ofrecer procedimientos efectivos con intención curativa asociándose a una baja sobrevida. Se hace necesario aumentar los esfuerzos para una pesquisa precoz y ofrecer un manejo terapéutico activo a estos pacientes.

Objective: Survival and prognostic factors analysis in Muscle-Invasive Bladder Cancer. Material and Methods: A retrospective analysis of patients with Muscle-Invasive Bladder Cancer between years 1996-2006. Survival analysis was made with Kaplan-Maier method and prognostic variables that affect the survival were analyzed. Results: Our study cohort included 78 patients who were hospitalized at the Urology Service with the diagnosis of Muscle-Invasive Bladder Cancer. The mean patient age was 69.11 years, being a 65.38 percent (51) men. Predominant histological type was Transitional Cell Carcinoma (69,2 percent). 52.5 percent (41/78 patients)under went Radical Cystectomy. The rest of the patients only received palliative procedures for the local control of the disease. According to staging (TNM-AJCC classification), 40 percent of the patients were diagnosed at stage II, 20 percent at stage III and 4 at stage IV. Mean follow up time was 22.1 months. Cancer specific survival estimated with Kaplan-Maier method was 54.3 percent, 34.6 percent, 25.9 percent for 1, 3 and 5 years respectively. Most important variable that correlates with survival was stage at diagnosis. Conclusion: In our series invasive bladder cancer is diagnosed at advanced stages (III and IV), which reduces the possibilities of getting effective procedures with curative intention, resulting in a low survival rates. It is mandatory improve the efforts in order to obtain a early diagnosis and to offer an active treatment to those patients.

Maternal melatonin effects on clock gene expression in a nonhuman primate fetus.

In the adult mammal the circadian system, which allows predictive adaptation to daily environmental changes, comprises peripheral oscillators in most tissues, commanded by the suprachiasmatic nucleus (SCN) of the hypothalamus. The external environment of the fetus is provided by its mother. In primates, maternal melatonin is a candidate to entrain fetal circadian rhythms, including the SCN rhythms of metabolic activity. We found in the 90% of gestation capuchin monkey fetus expression of the clock genes Bmal-1, Per-2, Cry-2, and Clock in the SCN, adrenal, pituitary, brown fat, and pineal. Bmal-1, Per-2, and the melatonin 1 receptor (MT1) showed a robust oscillatory expression in SCN and adrenal gland, whereas a circadian rhythm of dehydroepiandrosterone sulphate was found in plasma. Maternal melatonin suppression changed the expression of Bmal-1, Per-2, and MT1 in the fetal SCN. These effects were reversed by maternal melatonin replacement. In contrast, neither maternal melatonin suppression nor its replacement had effects on the expression of Per-2 and Bmal-1 or MT1 in the fetal adrenal gland or the circadian rhythm of fetal plasma dehydroepiandrosterone sulphate. Our data suggest that maternal melatonin is a Zeitgeber for the fetal SCN but probably not for the adrenal gland.

Differential effects of infralimbic cortical lesions on temperature and locomotor activity responses to feeding in rats.

The time of food availability induces important behavioral and metabolic adaptations. Animals subjected to feeding restricted to a few daytime hours show increased locomotor activity and body temperature in anticipation of mealtime. In addition, animals under ad libitum feeding show a marked postprandial raise in body temperature and in thermogenesis. The areas of the brain commanding these responses to food are partially known. We investigated in the rat the role of the infralimbic area, located in the medial prefrontal cortex, and considered a visceral-autonomic motor area, in the responses to ad libitum or restricted feeding schedule. We performed infralimbic cortex excitotoxic lesions using injections of ibotenic acid, and measured body temperature and locomotor activity by telemetry in rats under ad libitum and restricted feeding conditions. We found that bilateral infralimbic area lesions prevented both the anticipatory and the postprandial increases in core temperature, decreased mean temperature by nearly 0.3 degrees C during both light/dark phases, and increased daily temperature variability. In contrast, the lesion caused a rapid induction of the anticipatory locomotor activity. These results show that behavioral and metabolic responses to the time of food availability are commanded separately and that the infralimbic area is a key structure to adjust the body temperature to an upcoming meal.

Arousal and differential Fos expression in histaminergic neurons of the ascending arousal system during a feeding-related motivated behaviour.

Arousal depends on the concerted activity of the ascending arousal system (AAS) but specific stimuli may primarily activate some nuclei of this system. Motivated behaviours are characterized by behavioural arousal, although it is not known which AAS nuclei are active during a motivated behaviour. To address this issue, rats were rendered motivated for food by fasting them for 1 day and then were enticed with food that they could not obtain for varying periods of time. We studied the level of arousal by polysomnography or radiotelemetry, and Fos-ir in the AAS, during food enticing. We found a strong arousal and an early increase in Fos-ir in the histaminergic neurons from the tuberomammillary nucleus, after 30 min of enticing, followed by increased Fos-ir in the whole AAS if food enticing was prolonged to 1 or 2 hours. In contrast, food presentation to non-motivated rats did not increase arousal or Fos-ir in the tuberomammillary nucleus. As opposed to the active arousal of the motivated rats, passive arousal induced by sensory stimulation was associated with increased Fos-ir in the locus coeruleus and the orexin neurons, but not with increased Fos-ir in the tuberomammillary nucleus or in the other nuclei of the AAS. We conclude that the arousal during feeding-related motivated behaviour is associated primarily with the activation of the tuberomammillary nucleus, while the other arousal-related nuclei become active later on.

Colocalization of orexin a and glutamate immunoreactivity in axon terminals in the tuberomammillary nucleus in rats.

The orexins (also known as hypocretins) are peptide neurotransmitters made by hypothalamic neurons that are thought to play an important role in regulating wake-sleep states. One terminal area for orexin neurons is the tuberomammillary nucleus, a histaminergic cell group that is wake-active, but the relationship of the orexinergic terminals to the tuberomammillary neurons has not been examined in detail. We studied the ultrastructure of orexin A-immunoreactive axons and terminals in the tuberomammillary nucleus using pre- and post-embedding electron microscopic protocols. We confirmed an abundant projection of orexin-immunoreactive boutons to both dorsal and ventral divisions of the tuberomammillary nucleus. These terminals made asymmetric synaptic contacts with proximal and intermediate dendrites of tuberomammillary neurons. They contained small, clear synaptic vesicles and up to 30-40 dense core vesicles were seen per terminal in a single section. Both pre- and post-embedding immunostaining revealed that orexin immunoreactivity was localized to the dense core vesicles, which were always at a distance from the synaptic specialization. We also found glutamate immunoreactivity in the small synaptic vesicles which were at the active zone of the synapses of many of the same terminals. Orexinergic afferents to the tuberomammillary neurons contain separate populations of orexinergic and glutamatergic vesicles, suggesting that the release of these neurotransmitters may be differentially regulated.

The visceral sector of the thalamic reticular nucleus in the rat.

Visceral sensory perception is subjected to modulation by attention or distraction, like other sensory systems. The thalamic reticular nucleus is a key region in selective attention, effecting a change in the mode of thalamocortical transmission. Each major thalamocortical system is connected with a particular sector of the thalamic reticular nucleus. No connections from the thalamic reticular nucleus have been described to the visceral sensory thalamus. We used axonal tracing techniques to study the possible existence of reciprocal connections between the visceral sensory relay in the lateral ventroposterior parvicellular thalamic nucleus, and the reticular nucleus of the thalamus. We also studied the projections from the visceral sensory cortex, located in the granular insular cortex in the rat, to the reticular nucleus of the thalamus. We found a convergent input from both thalamic and cortical sensory visceral regions to the same sector of the reticular nucleus of the thalamus. This visceral sector in turn sent GABAergic feedback connections to the lateral ventroposterior parvicellular thalamic nucleus. In addition, the visceral thalamus received histaminergic projections from the tuberomammillary nucleus, and noradrenergic projections from the locus coeruleus; both nuclei belong to the ascending activating system. Our findings indicate that the visceral sensory thalamocortical pathway is connected to the same subcortical structures that provide attention mechanisms for other thalamocortical systems.

Anatomical substrate for separate processing of ascending and descending visceral information in the nucleus of the solitary tract of the rat.

We examined the possible existence of divergent visceral pathways arising from the nucleus of the solitary tract, by co-injecting axonal tracers into the parabrachial nucleus and into the ventrolateral medulla. We found that around 5% of NTS neurons projected to both sites, and that neurons projecting to VLM were larger. This parallel organization allows a differential control of the ascending versus descending visceral pathways at an early stage of processing.

Tuberomammillary nucleus activation anticipates feeding under a restricted schedule in rats.

We used FOS-immunoreactivity to map changes in the neuronal activity of brain nuclei related to the state of arousal, in rats under a restricted feeding schedule. Our main finding was the outstanding activation of the tuberomammillary nucleus 24h after a meal, and its steep deactivation, which was independent of actually having the meal. The time course of FOS activation and deactivation indicated a burst of tuberomammilary nucleus activity in close temporal relation with the increased locomotor activity shown by rats in anticipation of the next meal.