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Inhibition of median preoptic area neurons inhibits brown adipose tissue sympathetic outflow
No full textThe rostral raphe pallidus (rRPa) contains sympathetic premotor neurons controlling brown adipose tissue (BAT) thermogenesis and energy expenditure that are excited during cold-defense responses to skin cooling. Cutaneous thermal cold afferent signals are transmitted via the dorsal horn and lateral parabrachial nucleus to provide a glutamatergic drive to median preoptic area (MnPO) neurons that mediate skin-cooling evoked increases in BAT sympathetic nerve activity (SNA) and BAT temperature. The present study sought to determine whether there is a level of tonic discharge in MnPO neurons that contributes to the excitability of BAT sympathetic premotor neurons in the rRPa. In chloralose/urethane-anesthetized, artificially-ventilated Wistar rats, nanoinjection of GABA (9 nmol in 30 nl) into the midline MnPO elicited a long-lasting reduction in the amplitudes of the BAT SNA and heart rate responses (a) to nanoinjections of NMDA into the rRPa and (b) to episodes of skin cooling. We conclude that the MnPO contains a population of neurons whose tonic discharge supports the excitability of BAT and cardiac sympathetic premotor neurons in rRPa. Supported by a grant from NINDS: NS040987(SFM)
In a model of SAH-induced neurogenic fever, BAT thermogenesis is mediated by erythrocytes and blocked by agonism of adenosine A1 receptors
Full text linkNeurogenic fever (NF) after subarachnoid hemorrhage (SAH) is a major cause
of morbidity that is associated with poor outcomes and prolonged stay in the
neurointensive care unit (NICU). Though SAH is a much more common cause
of fever than sepsis in the NICU, it is often a diagnosis of exclusion, requiring
significant effort to rule out an infectious source. NF does not respond to
standard anti-pyretic medications such as COX inhibitors, and lack of good
medical therapy has led to the introduction of external cooling systems that
have their own associated problems. In a rodent model of SAH, we measured
the effects of injecting whole blood, blood plasma, or erythrocytes on the
sympathetic nerve activity to brown adipose tissue and on febrile
thermogenesis. We demonstrate that following SAH the acute activation of
brown adipose tissue leading to NF, is not dependent on PGE , that
subarachnoid space injection of whole blood or erythrocytes, but not plasma
alone, is sufficient to trigger brown adipose tissue thermogenesis, and that
activation of adenosine A1 receptors in the CNS can block the brown adipose
tissue thermogenic component contributing to NF after SAH. These findings
point to a distinct thermogenic mechanism for generating NF, compared to
those due to infectious causes, and will hopefully lead to new therapies
An excitatory projection from median preoptic area to the dorsomedial hypothalamus contributes to the activation BAT thermogenesis (1104.28)
No full textDisinhibition of brown adipose tissue (BAT) sympathoexcitatory neurons in the dorsomedial hypothalamus (DMH), by reduced discharge of their input from GABAergic, in the preoptic area (POA), is thought to be a key step in the cold-defense and febrile activations of BAT sympathetic nerve activity (SNA) and BAT thermogenesis. Here we present evidence supporting the hypothesis that a population of median preoptic area (MnPO) neurons projecting to the DMH provides the excitatory drive to DMH neurons that is essential for cold-defense and febrile BAT thermogenesis. To determine if the MnPO contains putative BAT thermogenesis-promoting neurons that are activated during cold exposure and project to DMH, we injected the retrograde tracer, CTb into DMH and exposed the rats to a cold (10°C) ambient temperature to elicit BAT thermogenesis. We observed a larger number of c-fos and CTb immunoreactive neurons in the MnPO of cold-exposed rats than in those maintained at 25°C, confirming the existence of cold-activated neurons in MnPO that project to DMH. In urethane/chloralose-anesthetized, Wistar rats, bilateral nanoinjection of the GABAA agonist, muscimol (120nl, 1mM), into the medial preoptic area (MPA), a region containing warm-sensitive neurons, did not decrease cold-evoked BAT SNA, consistent with the hypothesis that the MPA is not the source of DMH excitation required for BAT thermogenesis. However, subsequent nanoinjection of muscimol (120nl, 1mM) into the MnPO completely reversed cold-evoked BAT SNA. Moreover, in other experiments, the activation of BAT SNA following PGE2 nanoinjection into MPA was also inhibited by muscimol nanoinjection into MnPO. These data demonstrate that the MnPO contains essential thermogenesis-promoting, BAT sympathoexcitatory neurons
Thermoregulation in mice: The road to understanding torpor hypothermia and the shortcomings of a circuit for generating fever
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Parabrachial Complex: A Hub for Pain and Aversion
Full text linkThe parabrachial nucleus (PBN) has long been recognized as a sensory relay receiving an array of interoceptive and exteroceptive inputs relevant to taste and ingestive behavior, pain, and multiple aspects of autonomic control, including respiration, blood pressure, water balance, and thermoregulation. Outputs are known to be similarly widespread and complex. How sensory information is handled in PBN and used to inform different outputs to maintain homeostasis and promote survival is only now being elucidated. With a focus on taste and ingestive behaviors, pain, and thermoregulation, this review is intended to provide a context for analysis of PBN circuits involved in aversion and avoidance, and consider how information of various modalities, interoceptive and exteroceptive, is processed within PBN and transmitted to distinct targets to signal challenge, and to engage appropriate behavioral and physiological responses to maintain homeostasis
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Median preoptic area neurons are required for the cooling and febrile activations of brown adipose tissue thermogenesis in rat
Full text linkWithin the central neural circuitry for thermoregulation, the balance between excitatory and inhibitory inputs to the dorsomedial hypothalamus (DMH) determines the level of activation of brown adipose tissue (BAT) thermogenesis. We employed neuroanatomical and in vivo electrophysiological techniques to identify a source of excitation to thermogenesis-promoting neurons in the DMH that is required for cold defense and fever. Inhibition of median preoptic area (MnPO) neurons blocked the BAT thermogenic responses during both PGE2-induced fever and cold exposure. Disinhibition or direct activation of MnPO neurons induced a BAT thermogenic response in warm rats. Blockade of ionotropic glutamate receptors in the DMH, or brain transection rostral to DMH, blocked cold-evoked or NMDA in MnPO-evoked BAT thermogenesis. RNAscope technique identified a glutamatergic population of MnPO neurons that projects to the DMH and expresses c-Fos following cold exposure. These discoveries relative to the glutamatergic drive to BAT sympathoexcitatory neurons in DMH augment our understanding of the central thermoregulatory circuitry in non-torpid mammals. Our data will contribute to the development of novel therapeutic approaches to induce therapeutic hypothermia for treating drug-resistant fever, and for improving glucose and energy homeostasis
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