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Influenza dell'Omeostasi Idrico-Elettrolitica sul Ciclo Veglia-Sonno
No full textDuring the wake sleep (W-S) cycle in mammals, the alternation of the different states, wake, NREM sleep (NREMS) and REM sleep (REMS), is associated not only with electroencephalographic or behavioural changes, but also with modifications in the physiological regulations of the organism. The most evident change is the existence of a suspension of the somatic and autonomic thermoregulatory responses during REMS. Since thermoregulation is prevalently controlled by the Preoptic Area-Anterior Hypothalamus (PO-AH), its suspension during REM sleep has been taken as a sign of an impairment of the hypothalamic integrative activity that could explain the modifications in physiological regulation observed in this sleep stage.
The recent finding from our laboratory that the secretion of the antidiuretic hormone arginine-vasopressin (AVP) in response to a central osmotic stimulation is quantitatively the same throughout the different stages of the W-S cycle, has shown that hypothalamic osmoregulation is not suspended during REMS.
In order to clarify the extent of the hypothalamic involvement in the regulation of the W-S cycle, we have studied the effects of three days of water deprivation and of two days of recovery during which animals were allowed a free access to water, on the architecture of the W-S cycle. The condition of water deprivation represents a severe challenge involving neuroendocrine and autonomic hypothalamic regulations.
In contradiction with thermoregulatory studies, in which it has been clearly demonstrated that a thermal challenge selectively reduces REMS occurrence, the results of this study show that REMS occurrence is mildly reduced only in the third day of water deprivation. The most striking effects produced by water deprivation appear to concern NREMS, which shows a selective and significant reduction in its slow EEG activity (delta-power) but not in its duration. The recovery period is mainly characterized by a disruption of the normal circadian rhythm of REMS occurrence and by a rebound of the delta power in NREMS.
Thus, an autonomic challenge different from those related to thermoregulation and an endocrine challenge as the continuous secretion of AVP show to exert different effects on the stages of the wake-sleep cycle. Also, this study demonstrates that the impairment of the hypothalamic integrative activity thought to characterize the occurrence of REMS only involves thermoregulatory structures
The emerging role of the parabrachial complex in the generation of wakefulness drive and its implication for respiratory control
No full textThe parabrachial complex is classically seen as a major neural knot that transmits viscero- and somatosensory information toward the limbic and thalamic forebrain. In the present review we summarize recent findings that imply an emerging role of the parabrachial complex as an integral part of the ascending reticular arousal system, which promotes wakefulness and cortical activation. The ascending parabrachial projections that target wake-promoting hypothalamic areas and the basal forebrain are largely glutamatergic. Such fast synaptic transmission could be even more significant in promoting wakefulness and its characteristic pattern of cortical activation than the cholinergic or mono-aminergic ascending pathways that have been emphasized extensively in the past. A similar role of the parabrachial complex could also apply for its more established function in control of breathing. Here the parabrachial respiratory neurons may modulate and adapt breathing via the control of respiratory phase transition and upper airway patency, particularly during respiratory and non-respiratory behavior associated with wakefulness
Leptin Increases: Physiological Roles in the Control of Sympathetic Nerve Activity, Energy Balance, and the Hypothalamic–Pituitary–Thyroid Axis
Full text linkIt is well established that decreases in plasma leptin levels, as with fasting, signal starvation and elicit appropriate physiological responses, such as increasing the drive to eat and decreasing energy expenditure. These responses are mediated largely by suppression of the actions of leptin in the hypothalamus, most notably on arcuate nucleus (ArcN) orexigenic neuropeptide Y neurons and anorexic pro-opiomelanocortin neurons. However, the question addressed in this review is whether the effects of increased leptin levels are also significant on the long-term control of energy balance, despite conventional wisdom to the contrary. We focus on leptin’s actions (in both lean and obese individuals) to decrease food intake, increase sympathetic nerve activity, and support the hypothalamic–pituitary–thyroid axis, with particular attention to sex differences. We also elaborate on obesity-induced inflammation and its role in the altered actions of leptin during obesity
The autonomic inflammatory reflex
No full textImmune challenges are detected by the CNS, which then activates a sympathetic nerve pathway whose function is to dampen down the systemic inflammatory response to the immune challenge, in negative feedback manner. The afferent pathways whereby the CNS is informed of the immune challenge may be humoral and/or neural, but are not fully defined. The efferent pathway of the inflammatory reflex is in the splanchnic sympathetic nerves. Its antiinflammatory actions are mediated by several abdominal viscera, not just the spleen. When activated by systemic immune challenge, the reflex suppresses proinflammatory cytokine responses while enhancing antiinflammatory cytokine release. This reflex action is powerful, and can strongly influence the outcome of systemic bacterial infection. It appears to be a basic biological phenomenon that transcends species. Its full implications remain to be worked out
Reflex regulation of systemic inflammation by the autonomic nervous system
No full textThis short review focusses on the inflammatory reflex, which acts in negative feedback manner to moderate the inflammatory consequences of systemic microbial challenge. The historical development of the inflammatory reflex concept is reviewed, along with evidence that the endogenous reflex response to systemic inflammation is mediated by the splanchnic sympathetic nerves rather than by the vagi. We describe the coordinated nature of this reflex anti-inflammatory action: suppression of pro-inflammatory cytokines coupled with enhanced levels of the anti-inflammatory cytokine, interleukin 10. The limited information on the afferent and central pathways of the reflex is noted. We describe that the efferent anti-inflammatory action of the reflex is distributed among the abdominal viscera: several organs, including the spleen, can be removed without disabling the reflex. Understanding of the effector mechanism is incomplete, but it probably involves a very local action of neurally released noradrenaline on beta(2) adrenoceptors on the surface of tissue resident macrophages and other innate immune cells. Finally we speculate on the biological and clinical significance of the reflex, citing evidence of its power to influence the resolution of experimental bacteraemia
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
SYMPATHINF. Efficacy evaluation of non-selective beta-blocker prophylaxis in eradicating bacteremia in pigs
No full textThe dataset includes data on biochemical, hematological and physiological parameters, alongside flow cytometric analyses, resulting from an in vivo study aimed at testing in a pig model the efficacy of a pharmacological prophylaxis targeting sympathetic reflex control of immunity to mitigate systemic infection.
The trial was conducted in pigs subjected to porcine intravenous bacteremia and was performed at the Department of Veterinary Medical Sciences of the University of Bologna, within SYMPATHINF project. Briefly, all animals underwent surgical procedures for the insertion of a venous catheter and a telemetric disposable for the measurement of core body temperature. These surgical procedures were conducted five days before the bacterial challenge (in the files appointed as Day -5). Pigs were then randomly divided in two experimental groups (n=4 each): a control group (appointed as “Control”) and a group orally administered with propranolol (3 mg/Kg; 3x/day; appointed as “Propranolol-treated”), a non-selective beta-blocker which interrupts the communication between the sympathetic nerves and immune cells, limiting the anti-inflammatory action of sympathetic nervous system. The pharmacological treatment started two days before the bacterial challenge (appointed as Day -2) and was continued for the following 14 days (from Day2 to Day14, as appointed in the files). On the challenge day, each pig was intravenous injected with a bolus of 1.4x104 CFU/Kg of Escherichia coli. Throughout the study, blood samples were collected for various analyses, such as blood bacterial count, complete blood count, clinical chemistry analysis, flow cytometric assays on leukocytes harvested from pigs, to test their phagocytic capacity, in order to verify the efficacy of the pharmacological prophylaxis in eradicating the infection
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
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