Alucinosis peduncular en esclerosis múltiple, síntoma poco común en la expresión de enfermedad desmielinizante / Peduncular hallucinosis in multiple sclerosis, a rare symptom in demyelinating disease

Introducción: La alucinosis peduncular (AP) hace referencia a alucinaciones autodiscriminadas, cuyo origen son lesiones en el mesencéfalo y en el puente. Presentación del caso: Paciente 27 años, femenina, con alucinaciones visuales, auditivas autodiscriminadas por ella misma, sin antecedentes previos de importancia y con lesiones en resonancia magnética cerebral y cervical en el pedúnculo cerebeloso superior, tegmento pontino, y en columna cervical con bandas oligoclonales patrón 2, que cumplían criterios de Mc Donalds para esclerosis múltiple. Discusión: La alucinosis peduncular hace referencia a la presencia de alucinaciones visuales, criticadas por el paciente, con la consecuencia de lesiones de las vías inhibitorias por deaferentación y desinhibición mesencéfalotalámicas, y retinogenículo calcarina, descritas como manifestación de múltiples patologías neurológicas como trauma, afectación vascular, tumores y pocos casos de enfermedad desmielinizante, entre otras. Conclusión: La alucinosis peduncular es una forma atípica de presentación de lesiones pontomesencefálicas descritas en varias patologías; se debe tener en cuenta en la localización de la lesión neurológica; se han reportado pocos casos como síntoma de la enfermedad desmielinizante.

Introduction: Peduncular hallucinosis (PA) refers to self-discriminating hallucinations, these are caused by lesions in the midbrain and pons. Presentation of the case: 27-year-old right handed female patient with visual and auditory hallucinations self-discriminated by the patient, with no prior history of importance and with lesions in cerebral and cervical Magnetic Resonance in the superior cerebellar peduncle, pontine tegmentum, and in the cervical spine with pattern 2 oligo clonal bands, which met Mc Donald's criteria for multiple sclerosis. Discussion: Peduncular hallucinosis refers to the presence of visual hallucinations criticized by the patient, consequence of lesions in the inhibitory pathways with deafferentation and disinhibition of the midbrain-thalamic and retinogeniculus-calcarine pathways. Described as a manifestation of multiple neurological pathologies such as trauma, vascular, tumor and few cases of demyelinating among others. Conclusion: Peduncular hallucinosis is an atypical form of presentation of pontomesencephalic lesions described in several pathologies, it must be taken into account when locating the neurological lesion, few cases have been reported as symptom of the demyelinating disease.

S100 proteins and their implication in the thalamus: an integrative review / Las proteínas S100 y su implicación en el tálamo: una revisión integradora

SUMMARY: S100 proteins belong group of calcium-binding proteins and are present in physiological intracellular and extracellular regulatory activities, such as cell differentiation, and act in inflammatory and neoplastic pathological processes. Recently, its expressions in the nervous system have been extensively studied, seeking to elucidate its action at the level of the thalamus: A structure of the central nervous system that is part of important circuits, such as somatosensory, behavioral, memory and cognitive, as well as being responsible for the transmission and regulation of information to the cerebral cortex. This article is an integrative review of scientific literature, which analyzed 12 studies present in Pubmed. The analysis showed that the relationship of S100 proteins and the thalamus has been described in neoplastic processes, mental disorders, hypoxia, trauma, stress, infection, Parkinson's disease and epilepsy. In summary, it is possible to conclude that this protein family is relevant as a marker in processes of thalamic injury, requiring further studies to better understand its clinical, preclinical meanings and its prognostic value.

Las proteínas S100 pertenecen al grupo de proteínas fijadoras de calcio y están presentes en actividades reguladoras fisiológicas intracelulares y extracelulares, como la diferenciación celular, y actúan en procesos patológicos inflamatorios y neoplásicos. Recientemente, sus expresiones en el sistema nervioso han sido ampliamente estudiadas, buscando dilucidar su acción a nivel del tálamo: una estructura del sistema nervioso central que forma parte de importantes circuitos, como el somatosensorial, conductual, de memoria y cognitivo, así como además de ser responsable de la transmisión y regulación de la información a la corteza cerebral. Este artículo es una revisión integradora de la literatura científica, que analizó 12 estudios presentes en Pubmed. El análisis mostró que la relación de las proteínas S100 y el tálamo ha sido descrita en procesos neoplásicos, trastornos mentales, hipoxia, trauma, estrés, infección, enfermedad de Parkinson y epilepsia. En resumen, es posible concluir que esta familia de proteínas es relevante como marcador en procesos de lesión talámica, requiriendo más estudios para comprender mejor su significado clínico, preclínico y su valor pronóstico.

Cerebral localization of higher functions: anatomic structures before the identification of their memory function / Localização cerebral de funções superiores: estruturas anatômicas antes da identificação de suas funções de memória

The nature of memory and the search for its localization have been a subject of interest since Antiquity. After millennia of hypothetical concepts the core memory-related structures finally began to be identified through modern scientifically-based methods at the diencephalic, hippocampal, and neocortical levels. However, there was a clear temporal delay between the finding of these anatomic structures ignoring their function, and their identification related to memory function. Thus, the core structures begun to be identified with a pure anatomical view in the late Middle Ages on, while the memory function related to them was discovered much later, in the late Modern Period.

A natureza da memória e a busca de sua localização tem sido objeto de interesse desde a Antiguidade. Após milênios de conceitos hipotéticos as estruturas centrais relacionadas com a memória finalmente começaram a ser identificadas através de métodos modernos com base científica, nos níveis diencefálico, hipocampal e neocortical. Entretanto, houve um claro retardo temporal entre o achado dessas estruturas anatômicas ignorando sua função e sua identificação relacionada à função da memória. Assim, as estruturas centrais começaram a ser identificadas com uma visão puramente anatômica da Idade Média tardia em diante, enquanto a função da memória relacionada com as mesmas foi descoberta muito mais tarde, no Período Moderno tardio.

Cerebral localization of higher functions: Memory-related anatomic structures / Localização cerebral de funções superiores: estruturas anatômicas relacionadas com a memória. achados iniciais

ABSTRACT The nature of memory and the search for its localization have been a subject of interest since Antiquity. After millennia of theoretical concepts, shifting from the heart to the brain, then from the ventricles to solid parts, the core memory-related structures finally began to be identified through modern scientifically-based methods at the diencephalic and cortical (hippocampal and neocortical) levels, mostly in the late Modern period, culminating in the current state of knowledge on the subject.

RESUMO A natureza da memória e a busca de sua localização tem sido objeto de interesse desde a Antiguidade. Após milênios de conceitos teóricos, mudando do coração para o cérebro e daí dos ventrículos para as partes sólidas, as estruturas centrais relacionadas com a memória finalmente começaram a ser identificadas através de métodos modernos com base científica, nos níveis diencefálico e cortical (hipocampal e neocortical), principalmente no período Moderno tardio, aproximando-se do estado atual do conhecimento sobre o tema.

Comparative morphology and histology of the brain in Chinese toad ( Bufo gargarizans ) and chinese fire-billed newt ( Cynops orientalis ) / Morfología e histología comparada del cerebro en el sapo chino ( Bufo gargarizans ) y el tritón vientre de fuego chino ( Cynops orientalis )

The morphological and histological structure of the brains of Bufo gargarizans and Cynops orientalis were observed by anatomy and light microscopy. The results show that the brains of Bufo gargarizans and Cynops orientalis are divided into 5 parts which include the telencephalon, diencephalon, mesencephalon, cerebellum and medulla oblongata. The telencephalon consists of the olfactory bulb and the cerebral hemisphere. The olfactory bulb is developed that has two pairs of olfactory nerve. Bufo gargarizan has a symmetrical oval hemisphere optic lobes; Cynops orientalis only has a spherical optic lobe. The cerebellum is situated behind the optic lobe and closely connected with the myelencephalon. In this paper, the morphological and histological differences between the two species are discussed. The proportion of cerebral hemisphere is gradually increasing, which correlated with a progressive increase in the number of neuronal cell classes, and reflected in behavior complexity.

La estructura morfológica e histológica de los cerebros de Bufo gargarizans y Cynops orientalis se observó mediante anatomía y microscopía óptica. Los resultados muestran que los cerebros de Bufo gargarizans y Cynops orientalis se dividen en 5 partes, que incluyen el telencéfalo, diencéfalo, mesencéfalo, cerebelo y mielencéfalo. El telencéfalo consiste en bulbo olfatorio y hemisferio cerebral. El bulbo olfatorio tiene dos pares de nervios olfatorios. Los lóbulos ópticos de Bufo gargarizans son ovalados y simétricos en ambos hemisferios cerebrales; Cynops orientalis tiene solo un lóbulo óptico esférico. El cerebelo está situado detrás del lóbulo óptico y está estrechamente conectado con el mielencéfalo. En este trabajo, se discuten las diferencias morfológicas e histológicas entre las dos especies. El tamaño del hemisferio cerebral aumenta gradualmente, lo que se correlaciona con un aumento progresivo de células neuronales en los núcleos, reflejándose en la complejidad del comportamiento.

Signals from the caudal diencephalon are required for the projection of the Interstitial Nuclei of Cajal.

Axonal projection is controlled by discrete regions localized at the neuroepithelium, guiding the neurite growth during embryonic development. These regions exert their effect through the expression of a family of chemotropic molecules, which actively participate in the formation of neuronal connections of the central nervous system in vertebrates. Previous studies describe prosomere 1 (P1) as a possible organizer of axonal growth of the rostral rhombencephalon, contributing to the caudal projection of reticulospinal rhombencephalic neurons. This work studies the contribution of chemotropic signals from P1 or pretectal medial longitudinal fascicle (MLF) neurons upon the caudal projection of the interstitial nuclei of Cajal (INC). By using in ovo surgeries, retrograde axonal labeling, and immunohistochemical techniques, we were able to determine that the absence of P1 generates a failure in the INC caudal projection, while drastically diminishing the reticulospinal rhombencephalic neurons projections. The lack of INC projection significantly decreases the number of reticulospinal neurons projecting to the MLF. We found a 48.6% decrease in the projections to the MLF from the rostral and bulbar areas. Similarly, the observed decrease at prosomere 2 was 51.5%, with 61.8% and 32.4% for prosomeres 3 and 4, respectively; thus, constituting the most affected rostral regions. These results suggest the following possibilities: i, that the axons of the reticulospinal neurons employ the INC projection as a scaffold, fasciculating with this pioneer projection; and ii, that the P1 region, including pretectal MLF neurons, exerts a chemotropic effect upon the INC caudal projection. Nonetheless the identification of these chemotropic signals is still a pending task.

Monoaminergic levels at the forebrain and diencephalon signal for the occurrence of mutualistic and conspecific engagement in client reef fish.

Social interactions are commonly found among fish as in mammals and birds. While most animals interact socially with conspecifics some however are also frequently and repeatedly observed to interact with other species (i.e. mutualistic interactions). This is the case of the (so-called) fish clients that seek to be cleaned by other fish (the cleaners). Clients face an interesting challenge: they raise enough motivation to suspend their daily activities as to selectively visit and engage in interactions with cleaners. Here we aimed, for the first time, to investigate the region-specific brain monoaminergic level differences arising from individual client fish when facing a cleaner (interspecific context) compared to those introduced to another conspecific (socio-conspecific context). We show that monoaminergic activity differences occurring at two main brain regions, the diencephalon and the forebrain, are associated with fish clients' social and mutualistic activities. Our results are the first demonstration that monoaminergic mechanisms underlie client fish mutualistic engagement with cleanerfish. These pathways should function as a pre-requisite for cleaning to occur, providing to clients the cognitive and physiological tools to seek to be cleaned.

New Data from Pdfgb ret/ret Mutant Mice Might Lead to a Paradoxical Association Between Brain Calcification, Pericytes Recruitment and BBB Integrity.

Data of mice with PDGF-B-truncating mutation (Pdgfb ret/ret) from different research groups indicate that the malfunction of this protein leads to reduced pericyte recruitment, loss of Blood-Brain Barrier (BBB) integrity and bilateral brain calcification. This makes these mice important models for Primary Brain Calcification and pericyte-BBB correlation studies. The global brain pericyte count is reduced in Pdgfb ret/ret mice, with higher BBB permeability. We have overlapped the data from other research groups into a figure to further analyze the findings. Calcifications form within midbrain, interbrain, basal forebrain, and pons. Interestingly, these calcification-prone regions have a comparably higher pericyte count and lower BBB leakage in relation to other non-calcifying regions of the Pdgfb ret/ret mouse (such as the cortex and striatum). A comparatively higher BBB integrity in regions prone to calcification seems paradoxical and indicates that other region-specific changes are the cause of the calcifications.

Intermediate pilomyxoid astrocytoma and diencephalic syndrome: imaging findings / Astrocitoma pilomixoide intermediário e síndrome diencefálica: aspectos de imagem

Pilomyxoid astrocytoma, an entity described as a histological variant of pilocytic astrocytoma, is a rare primary tumor of the central nervous system. It is usually located in the hypothalamic-chiasmatic area, affecting children with a mean age of 10 months. It has a high rate of recurrence and cerebrospinal fluid dissemination, which may be present throughout the neuroaxis. Due to its topography, it may present developmental delay in childhood and diencephalic syndrome, characterized by extreme weight loss, lack of fat accumulation, hyperactivity, euphoria and alertness. Magnetic resonance imaging has an important role in its diagnosis, staging and follow-up of pilomyxoid astrocytoma. However, for a definitive diagnosis, anatomopathology is particularly important to differentiate it from pilocytic astrocytoma. Some cases, as in this present one, have simultaneous histological features of pilocytic and pilomyxoid astrocytomas, constituting a group called intermediate pilomyxoid astrocytoma. Surgery is the best treatment option and it usually requires adjuvant therapy.

O astrocitoma pilomixoide, entidade descrita como variante histológica do astrocitoma pilocítico, é um raro tumor primário do sistema nervoso central. Geralmente, localiza-se em topografia hipotálamoquiasmática, acomentendo crianças com idade média de 10 meses. Apresenta alta taxa de recorrência e disseminação liquórica, podendo se apresentar ao longo de todo o neuroeixo. Dada sua topografia, pode se apresentar com atraso do desenvolvimento na infância e síndrome diencefálica, caracterizada por emagrecimento extremo, ausência de acúmulo de tecido adiposo, hiperatividade motora, euforia e estado de alerta. A ressonância magnética possui um papel importante para o diagnóstico, estadiamento e seguimento do astrocitoma pilomixoide. No entanto, para o diagnóstico definitivo, o estudo anatomopatológico é fundamental, principalmente na diferenciação com o astrocitoma pilocítico. Além disso, em alguns casos, como o aqui apresentado, evidencia-se a apresentação simultânea de características histológicas do astrocitoma pilomixoide e pilocítico, constituindo um grupo denominado astrocitoma pilomixoide intermediário. A cirurgia é a melhor opção de tratamento e geralmente há necessidade de tratamento adjuvante.

Morphologic and immunohistochemical organization of the human habenular complex.

The habenular complex (HbCpx) is a phylogenetically conserved brain structure located in the epithalamus of vertebrates. Despite its fundamental role in decision-making processes and the proposed link between habenular dysfunction and neuropsychiatric conditions, little is known about the structural and functional organization of the HbCpx in humans. The goal of this study was thus to provide a first systematic morphologic and immunohistochemical analysis of the human HbCpx to begin dissecting its nuclear and subnuclear organization. Our results confirmed that the human HbCpx is subdivided into medial (MHb) and lateral (LHb) nuclei, each showing a large degree of intranuclear morphologic heterogeneity. Analysis of serially stained sections using a combination of morphologic and immunohistochemical criteria allowed the distinction of five subnuclei in both the MHb and LHb. Overall, the observed subnuclear organization of the MHb in humans resembles the organization of subnuclei in the MHb of rats. The shape, relative size, and intranuclear organization of the LHb, however, show significant differences. The contribution of the LHb to the entire HbCpx is about five times larger in humans than in rats. Noteworthy, a dorsal domain of the LHb that contains afferent myelinated fibers from the stria medullaris and shows GABA-(B) -R(1) immunoreactive cells, appears substantially enlarged in humans when compared to rats. This feature seems to account for a large part of the relative growth in size of the LHb in humans and opens the intriguing possibility of an increased influence of limbic and striatal afferents into the LHb of humans.

Subdivisions of chick diencephalic roof plate: implication in the formation of the posterior commissure.

The subcommissural organ (SCO) is a roof plate differentiation located in the caudal diencephalon under the posterior commissure (PC). A role for SCO and its secretory product, SCO-spondin, in the formation of the PC has been proposed. Here, we provide immunohistochemical evidence to suggest that SCO is anatomically divided in a bilateral region positive for SCO-spondin that surrounds a negative medial region. Remarkably, axons contacting the lateral region are highly fasciculated, in sharp contrast with the defasciculated axons of the medial region. In addition, lateral axon fascicles run toward the midline inside of tunnels limited by the basal prolongations of SCO cells and extracellular SCO-spondin. Our in vitro data in collagen gel matrices show that SCO-spondin induces axonal growth and fasciculation of pretectal explants. Together, our findings support the idea that SCO-spondin participates in the guidance and fasciculation of axons of the PC.

Differential Shh, Bmp and Wnt gene expressions during craniofacial development in mice.

In this study, Bmp-4, Wnt-5a and Shh gene expressions were compared during early craniofacial development in mice by comparative non-isotopic in situ hybridization. Wild-type C57BL/6J mice were studied at various stages of embryonic development (from 8.5- to 13.5-day-old embryos--E8.5-13.5). During early odontogenesis, transcripts for Bmp-4, Shh and Wnt-5a were co-localised at the tooth initiation stage. At E8.5, Shh mRNA expression was restricted to diencephalon and pharyngeal endoderm. Before maxillae and mandible ossification, Bmp-4 and Wnt-5a signals were detected in the mesenchymal cells and around Meckel's cartilage. During palatogenesis, Shh was expressed only in the epithelium and Wnt-5a only in the mesenchyme of the elevating palatal shelves. During tongue development, Shh expression was found in mesenchyme, probably contributing to tongue miogenesis, while Wnt-5a signal was in the epithelium, possibly during placode development and papillae formation. Taken together, these findings suggest that Bmp-4, Shh and Wnt-5a gene expressions may act together on the epithelial-mesenchymal interactions occurring in several aspects of the early mouse craniofacial development, such as odontogenesis, neuronal development, maxillae and mandible ossification, palatogenesis and tongue formation.

Polarized expression of integrin beta1 in diencephalic roof plate during chick development, a possible receptor for SCO-spondin.

The roof plate of the caudal diencephalon is formed by the posterior commissure (PC) and the underlying secretory ependyma, the subcommissural organ (SCO). The SCO is composed by radial glial cells bearing processes that cross the PC and attach to the meningeal basement membrane. Since early development, the SCO synthesizes SCO-spondin, a glycoprotein that shares similarities to axonal guidance proteins. In vitro, SCO-spondin promotes neuritic outgrowth through a mechanism mediated by integrin beta1. However, the secretion of SCO-spondin toward the extracellular matrix that surrounds the PC axons and the expression of integrins throughout PC development have not been addressed. Here we provide immunohistochemical evidence to suggest that during chick development SCO cells secrete SCO-spondin through their basal domain, where it is deposited into the extracellular matrix in close contact with axons of the PC that express integrin beta1. Our results suggest that SCO-spondin has a role in the development of the PC through its interaction with integrin beta1.

Distribution of tryptophan hydroxylase-immunoreactive neurons in the brainstem and diencephalon of the pigeon (Columba livia).

The distribution of tryptophan hydroxylase (TPH)-containing perikarya and processes in the brainstem and diencephalon of the pigeon (Columba livia) were investigated using single-labeling chromogenic and double-labeling fluorescence immunohistochemical methods for TPH and 5-HT. TPH-immunoreactive (TPH-ir) perikarya were seen extending from the caudal medulla to mid-hypothalamic levels, located in brainstem regions previously described as containing 5-HT-ir somata. Brainstem TPH-ir cell clusters (the midline raphe, and the dorsolateral and ventrolateral serotonergic cell groups) and the circumventricular cerebrospinal fluid-contacting neurons in the taenia choroidea (in the caudal brainstem), recessus infundibuli and paraventricular organ (in the hypothalamus) were shown to co-express 5-HT immunoreactivity. However, heavily labeled TPH-ir cell clusters were observed in the nucleus premamillaris (PMM), in the stratum cellulare internum (SCI), in the nucleus paraventricularis magnocellularis (PVN) and in the medial border of the nucleus dorsomedialis anterior thalami (DMA). Double-labeling experiments indicated that none of these medial hypothalamic TPH-ir cells were immunoreactive to 5-HT. These cells correspond to dopamine- and melatonin-containing neurons previously found in the avian hypothalamus, and appear to be comparable to the mammalian TPH-ir hypothalamic A11-A13 catecholaminergic somata, suggesting that they may be a conserved attribute in the amniote medial hypothalamus.

Role of brain nitric oxide in the thermoregulation of broiler chicks.

Nitric oxide (NO) plays a key role in body temperature (Tb) regulation of mammals, acting on the brain to stimulate heat loss. Regarding birds, the putative participation of NO in the maintenance of Tb in thermoneutrality or during heat stress and the site of its action (periphery or brain) is unknown. Thus, we tested if NO participates in the maintenance of chicks' Tb in those conditions. We investigated the effect of intramuscular (im; 25, 50, 100mg/kg) or intracerebroventricular (icv; 22.5, 45, 90, 180 microg/animal) injections of the non selective NO synthase inhibitor L-NAME on Tb of 5-day-old chicks at thermoneutral zone (TNZ; 31-32 degrees C) and under heat stress (37 degrees C for 5-6h). We also verified plasma and diencephalic nitrite/nitrate levels in non-injected chicks under both conditions. At TNZ, 100mg/kg (im) or 45, 90, 180 microg (icv) of L-NAME decreased Tb. A significant correlation between Tb and diencephalic, but not plasma, nitrite/nitrate levels was observed. Heat stress-induced hyperthermia was inhibited by all tested doses of L-NAME (im and icv). Tb was correlated neither with plasma nor with diencephalic nitrite/nitrate levels during heat stress. These results indicate the involvement of brain NO in the maintenance of Tb of chicks, an opposite action of that observed in mammals, and may modulate hyperthermia.

The medial forebrain bundle mediates cardiovascular responses to electrical stimulation of the medial prefrontal cortex.

The medial prefrontal cortex (MPFC) is involved in cardiovascular control. MPFC electrical stimulation has been reported to cause depressor and bradycardic responses in anesthetized rats. Although the pathway involved is yet unknown, there is evidence indicating the existence of a relay in the lateral hypothalamus (LH). The medial forebrain bundle (MFB) that courses in the lateral portion of the LH carries the vast majority of telencephalic afferent as well efferent projections, including those from the MPFC. To evaluate if the hypotensive pathway originating in the MPFC courses the MFB, we studied the effect of coronal or sagittal knife cuts through the LH and other brain areas on the cardiovascular responses to MPFC electrical stimulation. Knife cuts were performed using blades 1 to 6 mm wide. Results indicate that the neural pathway descending from the MFB decussates early in the vicinity of MPFC, crossing the midline within the corpus callosum and yielding two descending pathways that travel rostro-caudally in the lateral portion of the LH, within the MFB. The decussation was confirmed by histological analysis of brain sections processed after the injection of biotinilated dextran amine in the site of the stimulation in the MPFC. Because knife cuts through the LH ipsilateral had minimal effects on the cardiovascular responses and knife cuts performed contralateral to the stimulated MPFC had no effect on the response to MPFC stimulation, data indicate that the contralateral limb of the pathway may be only activated as an alternative pathway when the ipsilateral pathway is blocked.

Association between diencephalic thyroliberin and arterial blood pressure in agouti-yellow and ob/ob mice may be mediated by leptin.

Leptin, a hormone secreted by the adipose tissue, stimulates anorexigenic peptides and also inhibits orexigenic peptides in hypothalamic arcuate nuclei-located neurons. It also counteracts the starvation-induced suppression of thyroid hormones by up-regulating the expression of preproTRH gene. On the other hand, in addition to its role as a modulator of the thyroid-hypothalamic-hypophysial axis, thyrotropin-releasing hormone (TRH) acts as a modulator of the cardiovascular system. In fact, we reported that overexpression of diencephalic TRH (dTRH) induces hypertension. We have recently shown that, in rats with obesity-induced hypertension, hyperleptinemia may produce an increase of dTRH together with an elevation of arterial blood pressure (ABP) through an increase of sympathetic activity and that these alterations were reversed by antisense oligonucleotide and small interfering RNA against preproTRH treatments. Here we explore the possible role of dTRH as a mediator involved in leptin-induced hypertension in 2 obesity mouse models: agouti-yellow mice, which are hyperleptinemic and hypertensive, and ob/ob mice, which lack functional circulating leptin. These 2 models share some characteristics, but ob/ob mice show lower ABP and plasma catecholamines levels. Then, for the first time, we report that there is a clear association between ABP and dTRH levels in both mouse models, as we have found that dTRH content was elevated in agouti-yellow mice and diminished in ob/ob mice compared with their controls. We also show that, after 3 days of subcutaneous leptin injections (10 microg/12 hours), ABP and dTRH increased significantly in ob/ob mice with no alterations of thyroid hormone levels. These results add evidence to the putative molecular mechanisms for the strong association between obesity and hypertension.

Fiber connections of the diencephalic nucleus tuberis anterior in the weakly electric fish, Gymnotus cf. carapo: an in vivo tract-tracing study.

Transport of biotinylated dextran amine shows the spatial segregation of mechanosensory afferents in the nucleus tuberis anterior (TA) of a gymnotiform fish, Gymnotus cf. carapo. Only the intermediate subdivision of this nucleus receives projections from the lateral region of the ventral torus semicircularis (TSv), which represents the principal midbrain center for mechanosensory information processing, and from the ventral nucleus praeeminentialis, which receives collaterals of ascending second order mechanosensory fibers that emerge from the mechanosensory lateral line lobe. Considering this aspect, a rostrocaudal subdivision of the TA is proposed. The TA also receives input from regions subserving other sensory modalities, suggesting a role in multisensory interaction. Another important finding of this work consisted in the demonstration of reciprocal connections between the TA and the inferior lobe of the hypothalamus, which is known to receive gustatory, visual, and electrosensory input and is therefore considered a multisensory integration center involved in feeding and aggressive behavior. Furthermore, reciprocal connections between the TA and the preelectromotor central-posterior/prepacemaker complex may provide an access for the processed mechanosensory information to interact with the transient modulations of the electric organ discharge that accompany different behaviors.