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During 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.

We investigated a neural reflex that controls the strength of inflammatory responses to immune challenge - the inflammatory reflex. In anaesthetized rats challenged with intravenous lipopolysaccharide (LPS, 60 μg kg(-1)), we found strong increases in plasma levels of the key inflammatory mediator tumour necrosis factor α (TNFα) 90 min later. Those levels were unaffected by previous bilateral cervical vagotomy, but were enhanced approximately 5-fold if the greater splanchnic sympathetic nerves had been cut. Sham surgery had no effect, and plasma corticosterone levels were unaffected by nerve sections, so could not explain this result. Electrophysiological recordings demonstrated that efferent neural activity in the splanchnic nerve and its splenic branch was strongly increased by LPS treatment. Splenic nerve activity was dependent on inputs from the splanchnic nerves: vagotomy had no effect on the activity in either nerve. Together, these data demonstrate that immune challenge with this dose of LPS activates a neural reflex that is powerful enough to cause an 80% suppression of the acute systemic inflammatory response. The efferent arm of this reflex is in the splanchnic sympathetic nerves, not the vagi as previously proposed. As with other physiological responses to immune challenge, the afferent pathway is presumptively humoral: the present data show that vagal afferents play no measurable part. Because inflammation sits at the gateway to immune responses, this reflex could play an important role in immune function as well as inflammatory diseases.

Objectives: The Rostral Ventromedial Medulla (RVMM) is a key area in the control of autonomic function and metabolism, promoting thermogenesis (1). In the present study, the effects on sleep and cardiovascular parameters of the induction of a torpor-like state by the pharmacological inhibition of RVMM were investigated in the rat. Methods: Male Sprague–Dawley rats (n = 18, 300–350 g) adapted to an ambient temperature (Ta) of 25C, were implanted, under general anaesthesia (diazepam, 5 mg/kg, i.m., ketamine, 100 mg/kg, i.p.), with electrodes for EEG and EMG recording, a thermistor for detecting hypothalamic temperature (Thy), a catheter for arterial blood pressure recording, and a microcannula within the RVMM. After a week of recovery, animals were kept for 3 days at Ta 15C and then they were microinjected within the RVMM (1 injection/h, for 6 h) with either the GABAA agonist muscimol [1 mM, 100 nl; Group 1 (n = 6) and Group 2 (n = 6)] or saline [0.9%, 100 nl, Group 3 (n = 6)]. In order to favour the return to normothermia, 1 h after the last injection Ta was raised to 28C for Groups 1 and 3 and, for Group 2, to 37C, which was kept for 1 h and then taken to 28C. Results: Muscimol induced a deep hypothermia (Thy: 22.8 ± 0.8C) which was accompanied by: (i) a reduction of EEG activity; (ii) a decrease in heart rate (HR), from 440 ± 13 to 201 ± 12 bpm; (iii) a substantial maintenance of mean arterial pressure (MAP) at normal levels. Group 2 recovered normothermia faster than Group 1. Recovery was characterized by: (i) a progressive normalization of HR; (ii) the occurrence of a peak in MAP compared to saline (Group 3, 92 ± 4 mmHg), that was larger (P < 0.01) in Group 2 (125 ± 4 mmHg) than in Group 1 (116 ± 2 mmHg); (iii) the building up, in Groups 1 and 2, of a large SWS rebound in NREM sleep and of a not significant rebound in REM sleep. Conclusion: The effects of RVMM inhibition on cardiovascular and sleep parameters resembled those observed in natural torpor (2, 3). The increase in MAP observed during the recovery may be favoured by an excess in sympathetic activity. The effects on sleep observed after the recovery of normothermia indicate that the hypothermic bout and/or the rewarming generated a homeostatic need for SWS, but not for REM sleep. References: 1) Morrison S, Nakamura K. Front Biosci (2011) 16: 74–104. 2) Swoap SJ, Gutilla MJ. Am J Physiol RICP (2009) 297:R769–774. 3) Deboer T, Tobler I. Sleep (2003) 26: 567–72.

Introduction: The periods of torpor are typically followed by the occurrence of high-Delta power NREM sleep (NREMS) (1). In the present study, this phenomenon was investigated in rats through the induction of a torpor like state by the pharmacological inhibition of the Rostral Ventromedial Medulla (RVMM), a key area in the central nervous control of metabolism, promoting thermogenesis (2). Methods: Eighteen male Sprague-Dawley rats (300–350 g) were surgically implanted, under general anaesthesia (Diazepam, 5 mg/ kg, i.m., ketamine, 100 mg/kg, i.p.), with electrodes for chronic EEG recording, a thermistor for the detection of the hypothalamic temperature (Thy), a catheter for arterial blood presssure recording, and a microcannula for drug delivery within the RVMM. Before the experiment, animals were exposed for three days to ambient conditions that are known to favor the occurrence of a natural torpor bout: ambient temperature (Ta) 15C, constant darkness and a highfat diet. Three groups of animals were microinjected within the RVMM (1 injection/h, for 6 h) with the GABAA agonist muscimol (1 mM, 100 nl; Group 1 (n = 6) and Group 2 (n = 6)) or with saline (0.9%, 100 nl, group 3 (n = 6)). One hour after the last injections, Ta was raised to 28C for groups 1 and 3, and to 37C for Group 2 to favour the return to normothermia. Results: In both Group 1 and 2, a deep hypothermia was observed during the 6-h microinjection period (Thy fell to 22.80 ± 0.8C) which was accompanied by a decrease of EEG activity and a progressive shift of the EEG spectral power towards the low-frequency region. After the injection period, EEG activity showed a progressive increase and the EEG spectral power shifted to the high frequency region. In particular, after the recovery of normothermia, a powerful intensification of Delta power in NREMS was observed, which lasted about 6 h. The peak in Delta power was significantly higher in Group 1 than in Group 2 (P < 0.01). No significant effects were observed in Group 3. Conclusion: The dynamics of EEG changes during and after the torpor-like state induction were similar to those described in natural torpor. The increase in Delta power in NREMS was attenuated under environmental conditions promoting the restoration of normothermia, suggesting a role for the degree of sympathetic activation during restoration in its determination. 1. Deboer T, Tobler I. Sleep. 2003; 26: 567–72. 2. Morrison S, Nakamura K. Front Biosci., 2011; 16: 74–104.

Introduction: The antagonism of hypocretins (HCRT) has been proposed as a new approach to the treatment of insomnia. Since HCRT is exclusively synthesized by neurons located within the lateral hypothalamus (LH) [1], in the present study, we have evaluated the effects on sleep induced by a prolonged pharmacological inhibition of the LH at both normal laboratory (25C) and low (10C) ambient temperature (Ta), a condition which is known to dysfacilitate sleep ocurrence [2]. Methods: Twelve male Sprague-Dawley rats (300–350 g) were surgically implanted, under general anaesthesia (Diazepam, 5mg/ kg, i.m., ketamine, 100 mg/kg, i.p.), with electrodes for chronic EEG recording, a thermistor for the detection of the hypothalamic temperature, a catheter for arterial blood presssure recording and two microcannulas for drug delivery within the LH. Two groups of animals were studied under a 6-day (D1–D6) protocol. Animals from group 1 (n = 5) were injected with either the GABAA agonist Muscimol (100 nl, 1 mM, 1 injection/h for 6 h, from 11:00 h to 16:00 h) or vehicle (saline, 0.9%; according to the former protocol) during D2 and D5, respecitvely. In group 2 (n = 7), the same experimental protocol was carried out, but Ta was lowered to 10C in both D2 and D5, from 9:00 h to 17:00 h. Results: In the six experimental hours, muscimol injection induced a significant increase in NREM sleep amount at both Ta 25C (+6099 ± 574 s) and Ta 10C (+4896 ± 408 s) compared to what observed after vehicle (P < 0.01, for both comparisons). In both groups, a concomitant suppression of REM sleep was obsereved after muscimol injection Conclusion: The acute inhibition of LH neurons in free behaving rats produces a long bout of NREM sleep, even in environmental condition unfavourable to sleep occurence. This effect can be explained by the inhibition of the activity of HCRT neurons, which would favor the activation of the circuits promoting NREM sleep occurrence. The suppression of REM sleep may be due to the concomitant inhibithion of a group of melanin concentrating hormone (MCH) neurons located in the LH, which have been shown to be involved in REM sleep regulation [3]. 1. Sakurai T, Mieda M, Tsujino N. Ann N Y Acad Sci 2010, 1200: 149–61. 2. Cerri, M. Ocampo-Garces, A. Amici R, Baracchi F, Capitani P, Jones CA, Luppi M, Perez E, Parmeggiani PL, and Zamboni G. Sleep 2005, 28: 694:705. 3. Sapin E, Berod A, Leger L, Herman PA, Luppi PH, Peyron C. PLoS One 2010, 5: e11766.

The 'inflammatory reflex' acts through efferent neural connections from the central nervous system to lymphoid organs, particularly the spleen, that suppress the production of inflammatory cytokines. Stimulation of the efferent vagus has been shown to suppress inflammation in a manner dependent on the spleen and splenic nerves. The vagus does not innervate the spleen, so a synaptic connection from vagal preganglionic neurons to splenic sympathetic postganglionic neurons was suggested. We tested this idea in rats. In a preparatory operation, the anterograde tracer DiI was injected bilaterally into the dorsal motor nucleus of vagus and the retrograde tracer Fast Blue was injected into the spleen. On histological analysis 7-9 weeks later, 883 neurons were retrogradely labelled from the spleen with Fast Blue as follows: 89% in the suprarenal ganglia (65% left, 24% right); 11% in the left coeliac ganglion; but none in the right coeliac or either of the superior mesenteric ganglia. Vagal terminals anterogradely labelled with DiI were common in the coeliac but sparse in the suprarenal ganglia, and confocal analysis revealed no putative synaptic connection with any Fast Blue-labelled cell in either ganglion. Electrophysiological experiments in anaesthetized rats revealed no effect of vagal efferent stimulation on splenic nerve activity or on that of 15 single splenic-projecting neurons recorded in the suprarenal ganglion. Together, these findings indicate that vagal efferent neurons in the rat neither synapse with splenic sympathetic neurons nor drive their ongoing activity.

Studies conducted on anaesthetized animals have shown that neurons within the rostral ventromedial medulla (RVMM) can modulate the cardiac sympathetic outflow. Disinhibition of RVMM neurons by microinjection of the GABA-A antagonist bicuculline methiodide induces a strong increase in heart rate (HR), but inhibition of the same neurons by microinjection of the GABA-A agonist muscimol does not produce clear effects on HR. However, general anaesthesia affects sympathetic outflow and does not permit a evaluation of heart rate variability (HRV) measure. In the present study the role of RVMM neurons in mediating tonic cardiac sympathetic outflow has been assessed in free behaving rats. HRV has been evaluated in six free behaving rats before and after microinjection of muscimol (1mM) within the RVMM. HRV was analyzed within both the time domain (R-R mean; R-R standard deviation (STD-RR); root mean square successive difference (RMSSD)) and frequency domain (High (HF, 0.6–2.4 Hz) and Low Frequency (LF, 0.06–0.6 Hz) bands). Effects of injections were separated into six temporal blocks according to the dynamics of changes in core temperature following RVMM inhibition. At the end of the experiment, animals the site of injection was histologically verified. The power of the LF band, expression of cardiovascular sympathetic drive, was clearly reduced following RVMM neurons inhibition, suggesting that RVMM neurons participate in maintaining tonic cardiac sympathetic outflow.

A role of VentroMedian Medullary Raphe (VMMR) neurons in cardiovascular (CV) control is suggested by studies on anaesthetized animals. VMMR neuron disinhibition increased heart rate, arterial pressure and sympathetic outflow to the heart (1). However, it is thought that VMMR neurons do not maintain the tonic sympathetic CV drive, due to the lack of major CV effects after VMMR inhibition (2). Since general anaesthesia affects sympathetic outflow and does not permit the measurement of heart rate variability (HRV), in the present study the role of VMMR neurons in CV control has been assessed in free behaving rats. Six male CD rats (Charles River), kept under a 12h:12h light-dark cycle at 24±0.5°C ambient temperature were used. Under general anaesthesia (Diazepam, 5mg/Kg intramuscular; Ketamine-HCl, 100 mg/Kg, intraperitoneal), animals were implanted with electrodes for EEG and EKG recording, a thermistor to measure hypothalamic temperature (Thy), a microinjection guide cannula to target VMMR. One week after surgery, rats were randomly microinjected, on different days, with 100nl of the following: i) GABA-A agonist muscimol (1mM); ii) GABA-A antagonist bicuculline (1mM); iii) 0.9% saline. Preliminary analysis of data from muscimol injection was carried out during wake in two rats. HRV was analyzed within both the time (R-R mean; R-R standard deviation (STD-RR); root mean square successive difference (RMSSD)) and frequency domains (High (HF, 0.6–2.4 Hz) and Low Frequency (LF, 0.06–0.6 Hz) bands). Effects of injections were separated into six temporal blocks according to the dynamics of changes in core temperature following VMMR inhibition (3). At the end of the experiment, animals were sacrificed and histological control was carried out. Table 1 shows changes in HRV parameters and Thy (% of baseline levels, mean ± SEM) during the six temporal blocks. The LF band, expression of CV sympathetic drive, was clearly reduced following VMMR neurons inhibition. Changes in HRV parameters appeared to be specifically due to VMMR neuron inhibition and not to changes in Thy. In conclusion, VMMR neurons seem to participate in maintaining tonic sympathetic CV outflow.

Recent research proposes that putative sympathetic premotor neurons controlling cutaneous vasomotion are located within the rostral ventromedial medulla (RVMM), an area delimited rostrally by the nucleus of the facial nerve (RVMM(fn)) and caudally by the rostral pole of the inferior olive (RVMM(io)). Data from several experiments have shown that cutaneous blood flow is increased by the inhibition and reduced by the activation of neurons within the RVMM(fn), but no data are available on the role of the RVMM(io) on cutaneous vasomotion. To clarify the role of RVMM(fn) and RVMM(io) neurons in controlling cutaneous vasomotion, microinjection of the GABAA agonist muscimol and GABAA antagonist bicuculline methiodide were performed within the RVMM(fn) or the RVMM(io). A massive peripheral vasodilatation was evoked by muscimol injection within both the two areas, while disinhibition of either RVMM(fn) or RVMM(io) neurons produced, respectively, a reversal of the increase in cutaneous blood flow induced by warm exposure and an unexpected rapid cutaneous vasodilatation. The results show that two intermingled sets of neurons are located within the RVMM: a vasoconstrictory and thermoregulatory set, which is tonically active, is located in both the RVMM(io) and the RVMM(fn), while a vasodilatatory and non-thermoregulatory set, which is tonically inhibited, is located in the RVMM(io).

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In different species, REM sleep (REMS) occurrence appears to be finely regulated on either a short (Vivaldi E, 1994) or a long-term basis (Parmeggiani PL, 1980). However, the hypothesis that REMS amount is homeostatically regulated is challenged by data on humans which show that a scarce REMS rebound follows REMS deprivation (Horne J, 2000). Further analysis was carried out on data from an experiment in which 24 male Sprague-Dawley rats (250g) were exposed for 24h to different low ambient temperatures (Tas, ranging from –10°C to 10°C) and then allowed to recover for 4 days at normal laboratory Ta (Cerri M, 2005). REMS decreased proportionally with cold exposure, but a quick compensatory REMS rebound occurred during the first day of recovery when the previous loss went beyond an “alarm” threshold (AT) corresponding to 22% of the REMS daily need. By using data from literature we have calculated that AT for cats (Parmeggiani PL, 1980) and humans (Endo T, 1998) should correspond to 72% and 234% of the REMS daily need. Examining the three species together, AT appears to increase proportionally to the average duration of the REMS episode. It also appears to be positively related to their brain mass (Kg) according to a power function: y = 226.03x 0.36 , r2=0.986. This would suggest that, in analogy to what has been observed regarding the body’s energy needs, small mammals have a smaller capacity to buffer their REMS need than large ones.

Manual scoring of polysomnography data is labor-intensive and time-consuming, and most existing software does not account for subjective differences and user variability. Therefore, we evaluated a supervised machine learning algorithm, SomnivoreTM, for automated wake–sleep stage classification. We designed an algorithm that extracts features from various input channels, following a brief session of manual scoring, and provides automated wake-sleep stage classification for each recording. For algorithm validation, polysomnography data was obtained from independent laboratories, and include normal, cognitively-impaired, and alcohol-treated human subjects (total n = 52), narcoleptic mice and drug-treated rats (total n = 56), and pigeons (n = 5). Training and testing sets for validation were previously scored manually by 1–2 trained sleep technologists from each laboratory. F-measure was used to assess precision and sensitivity for statistical analysis of classifier output and human scorer agreement. The algorithm gave high concordance with manual visual scoring across all human data (wake 0.91 ± 0.01; N1 0.57 ± 0.01; N2 0.81 ± 0.01; N3 0.86 ± 0.01; REM 0.87 ± 0.01), which was comparable to manual inter-scorer agreement on all stages. Similarly, high concordance was observed across all rodent (wake 0.95 ± 0.01; NREM 0.94 ± 0.01; REM 0.91 ± 0.01) and pigeon (wake 0.96 ± 0.006; NREM 0.97 ± 0.01; REM 0.86 ± 0.02) data. Effects of classifier learning from single signal inputs, simple stage reclassification, automated removal of transition epochs, and training set size were also examined. In summary, we have developed a polysomnography analysis program for automated sleep-stage classification of data from diverse species. Somnivore enables flexible, accurate, and high-throughput analysis of experimental and clinical sleep studies., Frontiers in Neuroscience, 13, ISSN:1662-453X, ISSN:1662-4548

It 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 primary aim of this thesis has been to investigate the effects of central and peripheral Sympathetic Nervous System manipulation on immune responses and on hypothermia and sleep-related brain neural plasticity, through three different sub-projects. The first sub-project investigated the role of the endogenous inflammatory reflex in mice: it is activated in response to immune challenges and its efferent pathway, the splanchnic anti-inflammatory pathway (SAIP), inhibits the inflammatory response to immune challenges. The effects of prior bilateral section of the greater sympathetic splanchnic nerves on cytokine responses to three different systemic immune challenges were investigated: LPS, TLR4 agonist; Poly I:C, TLR3 agonist; and Pam2cys, TLR2 and TLR6 agonist. The results showed that each challenge active the SAIP in mice, resulting in the enhance of systemic levels of the anti-inflammatory cytokines and the inhibition of those of pro-inflammatory cytokines. The second sub-project investigated the effects of synthetic torpor (ST) and of the following recovery period on cortical and hippocampal Tau protein (τp) expression. Animals entering both natural and ST accumulate the hyperphosphorylated τp, resembling a similar pattern observed in tauopathies. However, this accumulation is reverted when animals recover from torpor. In this study, the levels of the τp, its phosphorylation/dephosphorylation processes, and the plasma levels of some hormones and transmitters were determined in rats subjected to and recovering from ST. The results confirmed the reversibility of the τp phosphorylation after the arousal from ST. Moreover, during ST and its recovery, plasma melatonin concentration increased. The third sub-project investigated the role of sleep, through a sleep deprivation protocol, in the levels of the τp and its phosphorylation/dephosphorylation processes, 3 and 6 hours after the exit from ST. The results showed that sleep deprivation did not impair τp dephosphorylation process, but apparently accelerated it through a finely regulated process, without affecting melatonin levels.

The splanchnic anti-inflammatory pathway has been proposed as the efferent arm of the inflammatory reflex. Although much evidence points to the spleen as the principal target organ where sympathetic nerves inhibit immune function, a systematic study to locate the target organ(s) of the splanchnic anti-inflammatory pathway has not yet been made. In anesthetized rats made endotoxemic with lipopolysaccharide (LPS, 60 µg/kg iv), plasma levels of tumor necrosis factor-α (TNF-α) were measured in animals with cut (SplancX) or sham-cut (Sham) splanchnic nerves. We confirm here that disengagement of the splanchnic anti-inflammatory pathway in SplancX rats (17.01 ± 0.95 ng/ml, mean ± SE) strongly enhances LPS-induced plasma TNF-α levels compared with Sham rats (3.76 ± 0.95 ng/ml). In paired experiments, the responses of SplancX and Sham animals were compared after the single or combined removal of organs innervated by the splanchnic nerves. Removal of target organ(s) where the splanchnic nerves inhibit systemic inflammation should abolish any difference in LPS-induced plasma TNF-α levels between Sham and SplancX rats. Any secondary effects of extirpating organs should apply to both groups. Surprisingly, removal of the spleen and/or the adrenal glands did not prevent the reflex splanchnic anti-inflammatory action nor did the following removals: spleen + adrenals + intestine; spleen + intestine + stomach and pancreas; or spleen + intestine + stomach and pancreas + liver. Only when spleen, adrenals, intestine, stomach, pancreas, and liver were all removed did the difference between SplancX and Sham animals disappear. We conclude that the reflex anti-inflammatory action of the splanchnic nerves is distributed widely across abdominal organs.

Tau is a key protein in neurons, where it affects the dynamicsof the microtubulesystem. The hyperphosphorylation of Tau (PP-Tau) commonlyleads to the formationof neurofibrillary tangles, as it occurs in tauopathies, a group of neurodegenerativediseases, including Alzheimer’s. Hypothermia-related accumulation of PP-Tau has beendescribed in hibernators and during synthetic torpor (ST),a torpor-like condition that hasbeen induced in rats, a non-hibernating species. Remarkably, in ST PP-Tau is reversibleand Tau de-phosphorylates within a few hours following the torpor bout, apparentlynot evolving into pathology. These observations have been limited to the brain, but inanimal models of tauopathies, PP-Tau accumulation also appears to occur in the spinalcord (SpCo). The aim of the present work was to assess whetherST leads to PP-Tauaccumulation in the SpCo and whether this process is reversible. Immunofluorescence(IF) for AT8 (to assess PP-Tau) and Tau-1 (non-phosphorylated Tau) was carried out onSpCo coronal sections. AT8-IF was clearly expressed in the dorsal horns (DH) duringST, while in the ventral horns (VH) no staining was observed.The AT8-IF completelydisappeared after 6h from the return to euthermia. Tau-1-IFdisappeared in both DH andVH during ST, returning to normal levels during recovery. Toshed light on the cellularprocess underlying the PP-Tau pattern observed, the inhibited form of the glycogen-synthase kinase 3β(the main kinase acting on Tau) was assessed using IF: VH (i.e., inmotor neurons) were highly stained mainly during ST, while in DH there was no staining.Since tauopathies are also related to neuroinflammation, microglia activation was alsoassessed through morphometric analyses, but no ST-inducedmicroglia activation wasfound in the SpCo. Taken together, the present results show that, in the DH of SpCo, STinduces a reversible accumulation of PP-Tau. Since during ST there is no motor activity,the lack of AT8-IF in VH may result from an activity-related process at a cellular level. Thus,ST demonstrates a newly-described physiological mechanism that is able to resolve theaccumulation of PP-Tau and apparently avoid the neurodegenerative outcome.Keywords: hypothermia, hibernation, microglia, tauopathies, GSK3β, motor neurons, adaptive response

none 6 si Electrical stimulation of the vagus nerve (VNS) is a novel strategy used to treat inflammatory conditions. Therapeutic VNS activates both efferent and afferent fibers; however, the effects attributable to vagal afferent stimulation are unclear. Here, we tested if selective activation of afferent fibers in the abdominal vagus suppresses systemic inflammation. In urethane-anesthetized rats challenged with lipopolysaccharide (LPS, 60µg/kg, i.v.), abdominal afferent VNS (2 Hz for 20 mins) reduced plasma tumor necrosis factor alpha (TNF) levels 90 minutes later by 88% compared with unmanipulated animals. Pre-cutting the cervical vagi blocked this anti-inflammatory action. Interestingly, the surgical procedure to expose and prepare the abdominal vagus for afferent stimulation ('vagal manipulation') also had an anti-inflammatory action. Levels of the anti-inflammatory cytokine IL-10 were inversely related to those of TNF. Prior bilateral section of the splanchnic sympathetic nerves reversed the anti-inflammatory actions of afferent VNS and vagal manipulation. Sympathetic efferent activity in the splanchnic nerve was shown to respond reflexly to abdominal vagal afferent stimulation. These data demonstrate that experimentally activating abdominal vagal afferent fibers suppresses systemic inflammation, and that the efferent neural pathway for this action is in the splanchnic sympathetic nerves. mixed Komegae, Evilin Naname; Stephen Farmer, David George; Brooks, Virginia Leah; McKinley, Michael Joseph; McAllen, Robin Michael; Martelli, Davide Komegae, Evilin Naname; Stephen Farmer, David George; Brooks, Virginia Leah; McKinley, Michael Joseph; McAllen, Robin Michael; Martelli, Davide

Mammals are characterized by a stable core body temperature. When maintenance of core temperature is challenged by ambient or internal heat loads, mammals increase blood flow to the skin, sweat and/or pant, or salivate. These thermoregulatory responses enable evaporative cooling at moist surfaces to dissipate body heat. If water losses incurred during evaporative cooling are not replaced, body fluid homeostasis is challenged. This article reviews the way mammals balance thermoregulation and osmoregulation.

A cellular degeneration of two thalamic nuclei belonging to the "limbic thalamus", i.e., the anteroventral (AV) and mediodorsal (MD) nuclei, has been shown in patients suffering from Fatal Familial Insomnia (FFI), a lethal prion disease characterized by autonomic activation and severe insomnia. To better assess the physiological role of these nuclei in autonomic and sleep regulation, c-Fos expression was measured in rats during a prolonged exposure to low ambient temperature (Ta, -10°C) and in the first hours of the subsequent recovery period at normal laboratory Ta (25°C). Under this protocol, the thermoregulatory and autonomic activation led to a tonic increase in waking and to a reciprocal depression in sleep occurrence, which was more evident for REM sleep. These effects were followed by a clear REM sleep rebound and by a rebound of Delta power during non-REM sleep in the following recovery period. In the anterior thalamic nuclei, c-Fos expression was (1) larger during the activity rather than the rest period in the baseline; (2) clamped at a level in-between the normal daily variation during cold exposure; (3) not significantly affected during the recovery period in comparison to the time-matched baseline. No significant changes were observed in either the MD or the paraventricular thalamic nucleus, which is also part of the limbic thalamus. The observed changes in the activity of the anterior thalamic nuclei appear, therefore, to be more specifically related to behavioral activation than to autonomic or sleep regulation.