Deep brain stimulation of thalamus for epilepsy.

Neuromodulation (neurostimulation) is a relatively new and rapidly growing treatment for refractory epilepsy. Three varieties are approved in the US: vagus nerve stimulation (VNS), deep brain stimulation (DBS) and responsive neurostimulation (RNS). This article reviews thalamic DBS for epilepsy. Among many thalamic sub-nuclei, DBS for epilepsy has been targeted to the anterior nucleus (ANT), centromedian nucleus (CM), dorsomedial nucleus (DM) and pulvinar (PULV). Only ANT is FDA-approved, based upon a controlled clinical trial. Bilateral stimulation of ANT reduced seizures by 40.5% at three months in the controlled phase (p = .038) and 75% by 5 years in the uncontrolled phase. Side effects related to paresthesias, acute hemorrhage, infection, occasional increased seizures, and usually transient effects on mood and memory. Efficacy was best documented for focal onset seizures in temporal or frontal lobe. CM stimulation may be useful for generalized or multifocal seizures and PULV for posterior limbic seizures. Mechanisms of DBS for epilepsy are largely unknown, but animal work points to changes in receptors, channels, neurotransmitters, synapses, network connectivity and neurogenesis. Personalization of therapies, in terms of connectivity of the seizure onset zone to the thalamic sub- nucleus and individual characteristics of the seizures, might lead to improved efficacy. Many questions remain about DBS, including the best candidates for different types of neuromodulation, the best targets, the best stimulation parameters, how to minimize side effects and how to deliver current noninvasively. Despite the questions, neuromodulation provides useful new opportunities to treat people with refractory seizures not responding to medicines and not amenable to resective surgery.

Changes of nNOS expression in the tuberal hypothalamic nuclei during ageing.

The hypothalamus is the most important integrator of autonomic and endocrine regulation in the body and it also has a fundamental role in ageing development and lifespan control. In order to better understand the role of NO-ergic system in the hypothalamic regulation of ageing, the purpose of this study was to investigate the expression of neuronal nitric oxide synthase (nNOS) in the arcuate (ARC), ventromedial (VMH) and dorsomedial (DMH) hypothalamic nuclei in young (2-3-month-old) and old (24-month-old) male and female rats using immunohistochemistry and western blot analysis. In young animals, only single nNOS-immunoreactive (IR) neurons were detected in ARC, and nNOS-IR neurons were found in the VMH (19 ± 3.2% in females and 14.5 ± 2.6% in males) and DMH (17 ± 4.0% in females and 21 ± 2.8% in males). In aged animals, the number of nNOS-IR neurons increased in all studied nuclei, including ARC (36 ± 3.1% in females and 33.5 ± 3.7% in males), VMH (83 ± 4.3% in females and 58 ± 2.1% in males) and DMH (57 ± 1.9% in females and 54 ± 1.8% in males). The expression of nNOS also significantly increased in the ARC, VMH and DMH during ageing by western blot analysis. In conclusion, ageing is accompanied by increasing of nNOS expression in the hypothalamus and this process is related to regions involved in the control of feeding behavior.

Oxyntomodulin induces satiety and activates the arcuate nucleus of the hypothalamus in Japanese quail.

Oxyntomodulin (OXM) is a proglucagon-derived peptide that suppresses hunger in humans. There are some differences in its food intake-inhibitory effects among species. The central mechanisms are unclear and it is unknown if OXM is more efficacious in a gallinaceous species that has not undergone as much selection for growth as the chicken. The objective was thus to determine the effects of OXM on food and water intake and hypothalamic physiology in Japanese quail. At 7 days post-hatch, 6-h-fasted quail were injected intracerebroventricularly (ICV) or intraperitoneally (IP) with 0.32, 0.65, or 1.3 nmol of OXM. All doses decreased food intake for 180 min post-ICV injection. On a cumulative basis, water intake was not affected until 120 min, with the lowest and highest doses decreasing water intake after ICV injection. The two highest doses were anorexigenic when administered via the IP route, whereas all doses were anti-dipsogenic starting at 30 min post-injection. In hypothalamic samples collected at 1-h post-ICV injection, there was an increase in c-Fos immunoreactivity, an indicator of recent neuronal activation, in the arcuate nucleus (ARC) and dorsomedial nucleus (DMN) of the hypothalamus in OXM-injected individuals. Results suggest that quail are more sensitive than chickens to the satiety-inducing effects of OXM. The central mechanism is likely mediated through a pathway in the ARC that is conserved among species, and through activation of the DMN, an effect that is unique to quail. Such knowledge is critical for facilitating the development of novel, side effect-free anti-eating strategies to promote weight-loss in obesity.

The hypothalamus at the crossroads of psychopathology and neurosurgery.

The neurosurgical endeavor to treat psychiatric patients may have been part of human history since its beginning. The modern era of psychosurgery can be traced to the heroic attempts of Gottlieb Burckhardt and Egas Moniz to alleviate mental symptoms through the ablation of restricted areas of the frontal lobes in patients with disabling psychiatric illnesses. Thanks to the adaptation of the stereotactic frame to human patients, the ablation of large volumes of brain tissue has been practically abandoned in favor of controlled interventions with discrete targets. Consonant with the role of the hypothalamus in the mediation of the most fundamental approach-avoidance behaviors, some hypothalamic nuclei and regions, in particular, have been selected as targets for the treatment of aggressiveness (posterior hypothalamus), pathological obesity (lateral or ventromedial nuclei), sexual deviations (ventromedial nucleus), and drug dependence (ventromedial nucleus). Some recent improvements in outcomes may have been due to the use of stereotactically guided deep brain stimulation and the change of therapeutic focus from categorical diagnoses (such as schizophrenia) to dimensional symptoms (such as aggressiveness), which are nonspecific in terms of formal diagnosis. However, agreement has never been reached on 2 related issues: 1) the choice of target, based on individual diagnoses; and 2) reliable prediction of outcomes related to individual targets. Despite the lingering controversies on such critical aspects, the experience of the past decades should pave the way for advances in the field. The current failure of pharmacological treatments in a considerable proportion of patients with chronic disabling mental disorders is reminiscent of the state of affairs that prevailed in the years before the early psychosurgical attempts. This article reviews the functional organization of the hypothalamus, the effects of ablation and stimulation of discrete hypothalamic regions, and the stereotactic targets that have most often been used in the treatment of psychopathological and behavioral symptoms; finally, the implications of current and past experience are presented from the perspective of how this fund of knowledge may usefully contribute to the future of hypothalamic psychosurgery.

Stimulation of the hypothalamic arcuate nucleus increases brown adipose tissue nerve activity via hypothalamic paraventricular and dorsomedial nuclei.

Hypothalamic arcuate nucleus (ARCN) stimulation elicited increases in sympathetic nerve activity (IBATSNA) and temperature (TBAT) of interscapular brown adipose tissue (IBAT). The role of hypothalamic dorsomedial (DMN) and paraventricular (PVN) nuclei in mediating these responses was studied in urethane-anesthetized, artificially ventilated, male Wistar rats. In different groups of rats, inhibition of neurons in the DMN and PVN by microinjections of muscimol attenuated the increases in IBATSNA and TBAT elicited by microinjections of N-methyl-d-aspartic acid into the ipsilateral ARCN. In other groups of rats, blockade of ionotropic glutamate receptors by combined microinjections of D(-)-2-amino-7-phosphono-heptanoic acid (D-AP7) and NBQX into the DMN and PVN attenuated increases in IBATSNA and TBAT elicited by ARCN stimulation. Blockade of melanocortin 3/4 receptors in the DMN and PVN in other groups of rats resulted in attenuation of increases in IBATSNA and TBAT elicited by ipsilateral ARCN stimulation. Microinjections of Fluoro-Gold into the DMN resulted in retrograde labeling of cells in the ipsilateral ARCN, and some of these cells contained proopiomelanocortin (POMC), α-melanocyte-stimulating hormone (α-MSH), or vesicular glutamate transporter-3. Since similar projections from ARCN to the PVN have been reported by us and others, these results indicate that neurons containing POMC, α-MSH, and glutamate project from the ARCN to the DMN and PVN. Stimulation of ARCN results in the release of α-MSH and glutamate in the DMN and PVN which, in turn, cause increases in IBATSNA and TBAT.

Cessation of gamma activity in the dorsomedial nucleus associated with loss of consciousness during focal seizures.

RATIONALE: Impaired consciousness during seizures may be mediated by ictal propagation to the thalamus. Functions of individual thalamic nuclei with respect to consciousness, however, are largely unknown. The dorsomedial (DM) nucleus of the thalamus likely plays a role in arousal and cognition. We propose that alterations of firing patterns within the DM nucleus contribute to impaired arousal during focal seizures. METHODS: Electroencephalograph data were collected from electrodes within the left DM thalamus and midcingulate cortex (MCC) in a patient undergoing seizure monitoring. Spectral power was computed across ictal states (preictal, ictal, and postictal) and level of consciousness (stupor/sleep vs. awake) in the DM nucleus and MCC. RESULTS: Eighty-seven seizures of multifocal left frontal and temporal onsets were analyzed, characterized by loss of consciousness. At baseline, the left DM nucleus demonstrated rhythmic bursts of gamma activity, most frequently and with greatest amplitude during wakefulness. This activity ceased as ictal discharges spread to the MCC, and consciousness was impaired, and it recurred at the end of each seizure as awareness was regained. The analysis of gamma (30-40Hz) power demonstrated that when seizures occurred during wakefulness, there was lower DM ictal power (p<0.0001) and higher DM postictal power (p<0.0001) relative to the preictal epoch. This spectral pattern was not evident within the MCC or when seizures occurred during sleep. CONCLUSIONS: Data revealed a characteristic pattern of DM gamma bursts during wakefulness, which disappeared during partial seizures associated with impaired consciousness. The findings are consistent with studies suggesting that the DM nucleus participates in cognition and arousal.

Ghrelin receptor-knockout mice display alterations in circadian rhythms of activity and feeding under constant lighting conditions.

Ghrelin is an orexigenic hormone produced by the stomach. Ghrelin, however, may also be a modulator of the circadian system given that ghrelin receptors are expressed in the master clock, the suprachiasmatic nucleus (SCN) and several outputs of this region. To investigate this, we performed analyses of running wheel activity and neuronal activation in wild type (WT) and growth hormone secretagogue receptor-knockout (GHSR-KO) mice under various lighting conditions. GHSR-KO and WT mice were maintained under constant dark (DD) or constant light (LL) with ad libitum access to food before being placed on a schedule of temporally restricted access to food (4 h/day) for 2 weeks. There were no differences between KO and WT mice in free-running period under DD, but GHSR-KO mice required more days to develop a high level of food anticipatory activity, and this was lower than that observed in WT mice. Under LL, GHSR-KO mice showed greater activity overall, lengthening of their circadian period, and more resistance to the disorganisational effects of LL. Furthermore, GHSR-KO mice showed greater activity overall, and greater activity in anticipation of a scheduled meal under LL. These behavioral effects were not correlated with changes in the circadian expression of the Fos, Per1 or Per2 proteins under any lighting conditions. These results suggest that the ghrelin receptor plays a role in modulating the activity of the circadian system under normal conditions and under restricted feeding schedules, but does so through mechanisms that remain to be determined.

Sex-dependent and -independent regulation of thyrotropin-releasing hormone expression in the hypothalamic dorsomedial nucleus by negative energy balance, exercise, and chronic stress.

The dorsomedial nucleus of the hypothalamus (DMH) is part of the brain circuits that modulate organism responses to the circadian cycle, energy balance, and psychological stress. A large group of thyrotropin-releasing hormone (Trh) neurons is localized in the DMH; they comprise about one third of the DMH neurons that project to the lateral hypothalamus area (LH). We tested their response to various paradigms. In male Wistar rats, food restriction during adulthood, or chronic variable stress (CVS) during adolescence down-regulated adult DMH Trh mRNA levels compared to those in sedentary animals fed ad libitum; two weeks of voluntary wheel running during adulthood enhanced DMH Trh mRNA levels compared to pair-fed rats. Except for their magnitude, female responses to exercise were like those in male rats; in contrast, in female rats CVS did not change DMH Trh mRNA levels. A very strong negative correlation between DMH Trh mRNA levels and serum corticosterone concentration in rats of either sex was lost in CVS rats. CVS canceled the response to food restriction, but not that to exercise in either sex. TRH receptor 1 (Trhr) cells were numerous along the rostro-caudal extent of the medial LH. In either sex, fasting during adulthood reduced DMH Trh mRNA levels, and increased LH Trhr mRNA levels, suggesting fasting may inhibit the activity of TRHDMH->LH neurons. Thus, in Wistar rats DMH Trh mRNA levels are regulated by negative energy balance, exercise and chronic variable stress through sex-dependent and -independent pathways.

The anorexigenic effect of vasoactive intestinal polypeptide in Japanese quail is associated with molecular changes in the arcuate and dorsomedial hypothalamic nuclei.

Vasoactive intestinal polypeptide (VIP) is involved in gastric smooth muscle relaxation, vasodilation, and gastric secretions. It is also associated with appetite regulation, eliciting an anorexigenic response in mammals, birds, and fish; however, the molecular mechanism mediating this response is not well understood. The aim of the present study was thus to investigate hypothalamic mechanisms mediating VIP-induced satiety in 7-d old Japanese quail. In experiment 1, chicks that received intracerebroventricular (ICV) injection of VIP had reduced food intake for up to 180 min after injection and reduced water intake for 90 min. In experiment 2, VIP-treated chicks that were food restricted did not reduce water intake. In experiment 3, there was increased c-Fos immunoreactivity in the arcuate (ARC) and dorsomedial (DMN) nuclei of the hypothalamus in VIP-injected quail. In experiment 4, ICV VIP was associated with decreased neuropeptide Y mRNA in the ARC and DMN and an increase in corticotropin releasing factor mRNA in the DMN. In experiment 5, VIP-treated chicks displayed fewer feed pecks and locomotor behaviors. These results demonstrate that central VIP causes anorexigenic effects that are likely associated with reductions in orexigenic tone involving the ARC and DMN.

The orexin/hypocretin system in neuropsychiatric disorders: Relation to signs and symptoms.

Hypocretin-1 and 2 (or orexin A and B) are neuropeptides exclusively produced by a group of neurons in the lateral and dorsomedial hypothalamus that project throughout the brain. In accordance with this, the two different hypocretin receptors are also found throughout the brain. The hypocretin system is mainly involved in sleep-wake regulation, but also in reward mechanisms, food intake and metabolism, autonomic regulation including thermoregulation, and pain. The disorder most strongly linked to the hypocretin system is the primary sleep disorder narcolepsy type 1 caused by a lack of hypocretin signaling, which is most likely due to an autoimmune process targeting the hypocretin-producing neurons. However, the hypocretin system may also be affected, but to a lesser extent and less specifically, in various other neurological disorders. Examples are neurodegenerative diseases such as Alzheimer's, Huntington's and Parkinson's disease, immune-mediated disorders such as multiple sclerosis, neuromyelitis optica, and anti-Ma2 encephalitis, and genetic disorders such as type 1 diabetus mellitus and Prader-Willi Syndrome. A partial hypocretin deficiency may contribute to the sleep features of these disorders.

A spontaneous leptin receptor point mutation causes obesity and differentially affects leptin signaling in hypothalamic nuclei resulting in metabolic dysfunctions distinct from db/db mice.

OBJECTIVE: Leptin (Lep) plays a crucial role in controlling food intake and energy expenditure. Defective Lep/LepRb-signaling leads to fat accumulation, massive obesity, and the development of diabetes. We serendipitously noticed spontaneous development of obesity similar to LepR-deficient (db/db) mice in offspring from a C57BL/6J breeding and transmittance of the phenotype in a Mendelian manner. Candidate gene sequencing revealed a spontaneous point mutation in the LepRb gene. We investigated leptin responsiveness, leptin receptor signaling and metabolic phenotype of this novel LepRb mutant mouse variant. METHODS: Overexpression and functional tests of the mutant LepRb in 3T3 cells. Measurement of leptin responsiveness in hypothalamic nuclei, glucose tolerance, food uptake and energy expenditure in the mutant mice. RESULTS: The mutation results in the exchange of a glycine for serine (G506S) and introduces an alternative splice acceptor which, when used, encodes for a protein with a 40aa deletion that is retained in the cytoplasm. LepRb signaling was abrogated in the hypothalamic ventromedial nucleus (VMN) and dorsomedial nucleus (DMN), but only partially reduced in the hypothalamic arcuate nucleus (ARC) of LepRbG506S/G506S mice, most likely due to differential splicing in neurons located in the respective regions of the hypothalamus. Extensive metabolic characterization of these mice revealed interesting differences in the control of food intake, glucose tolerance, energy expenditure, and fat accumulation in LepRbG506S/G506S compared with LepRb-deficient db/db mice. CONCLUSIONS: This study provides further insight into differences of the leptin responsiveness in VMN, DMN, and ARC and its metabolic consequences.

The rostromedial zona incerta is involved in attentional processes while adjacent LHA responds to arousal: c-Fos and anatomical evidence.

Neurons producing melanin-concentrating hormone (MCH) are located in the tuberal lateral hypothalamus (LHA) and in the rostromedial part of the zona incerta (ZI). This distribution suggests that rostromedial ZI shares some common features with the LHA. However, its functions with regard to arousal or feeding, which are often associated with the LHA, have not been thoroughly investigated. This study analyses the responses in the tuberal LHA and adjacent rostromedial ZI after experiments related to arousal, exploration, food teasing and ingestive behavior. Specific aspects of the connections of the rostromedial ZI were also studied using retrograde and anterograde tract-tracing approaches. The rostromedial ZI is activated during exploratory and teasing experiments. It receives specific projections from the frontal eye field and the anterior pole of the superior colliculus that are involved in gaze fixation and saccadic eye movements. It also receives projections from the laterodorsal tegmental nucleus involved in attention/arousal. By contrast, the tuberal LHA is activated during wakefulness and exploratory behavior and reportedly receives projections from the medial prefrontal and insular cortex, and from several brainstem structures such as the periaqueductal gray. We conclude that the rostromedial ZI is involved in attentional processes while the adjacent tuberal LHA is involved in arousal.

The central effects of alpha-melanocyte stimulating hormone (α-MSH) in chicks involve changes in gene expression of neuropeptide Y and other factors in distinct hypothalamic nuclei.

Alpha-melanocyte stimulating hormone (α-MSH) is a satiety-inducing factor in birds and mammals although central mechanisms mediating its effects on appetite in birds are poorly understood. Thus, the objective of the present study was to determine effects of centrally-injected α-MSH on c-Fos and gene expression in chick appetite-associated hypothalamic nuclei. At 4days post-hatch, 3h-fasted chicks were intracerebroventricularly (ICV) injected with 0 (vehicle) or 0.12nmol α-MSH and 1h later, hypothalamus samples were collected for measuring c-Fos immunoreactivity and mRNA abundance of appetite-associated factors in hypothalamic nuclei. There were more c-Fos immunoreactive cells in the arcuate nucleus (ARC), dorsomedial nucleus (DMN), lateral hypothalamus (LH), and paraventricular nucleus (PVN) of α-MSH- than vehicle-injected chicks. Neuropeptide Y (NPY), oxytocin receptor (OXTR), and agouti-related peptide (AgRP) mRNAs were greater in α-MSH- than vehicle-injected chicks in the ARC. In the PVN, NPY receptor sub-type 1 (NPYR1) mRNA was reduced while c-Fos mRNA was increased in response to treatment with α-MSH. NPY, c-Fos, and DOPA decarboxylase (DDC) mRNAs were greater in treated than vehicle-injected chicks in the DMN. Results suggest that during the first hour post-injection, the appetite-inhibiting effects of α-MSH involve activation of the ARC, DMN, PVN, and LH, and corresponding changes in transcriptional regulation of factors involved with NPY, AgRP and mesotocin signaling, and monoamine synthesis. The effects of these changes may include an inhibition of NPY signaling in the PVN to induce satiety and stimulation of NPY/AgRP neurons in the ARC in an attempt to restore homeostatic levels of food intake.

Adult exposure to tributyltin affects hypothalamic neuropeptide Y, Y1 receptor distribution, and circulating leptin in mice.

Tributyltin (TBT), a pesticide used in antifouling paints, is toxic for aquatic invertebrates. In vertebrates, TBT may act in obesogen- inducing adipogenetic gene transcription for adipocyte differentiation. In a previous study, we demonstrated that acute administration of TBT induces c-fos expression in the arcuate nucleus. Therefore, in this study, we tested the hypothesis that adult exposure to TBT may alter a part of the nervous pathways controlling animal food intake. In particular, we investigated the expression of neuropeptide Y (NPY) immunoreactivity. This neuropeptide forms neural circuits dedicated to food assumption and its action is mediated by Y1 receptors that are widely expressed in the hypothalamic nuclei responsible for the regulation of food intake and energy homeostasis. To this purpose, TBT was orally administered at a dose of 0.025 mg/kg/day/body weight to adult animals [male and female C57BL/6 (Y1-LacZ transgenic mice] for 4 weeks. No differences were found in body weight and fat deposition, but we observed a significant increase in feed efficiency in TBT-treated male mice and a significant decrease in circulating leptin in both sexes. Computerized quantitative analysis of NPY immunoreactivity and Y1-related ß-galactosidase activity demonstrated a statistically significant reduction in NPY and Y1 transgene expression in the hypothalamic circuit controlling food intake of treated male mice in comparison with controls. In conclusion, the present results indicate that adult exposure to TBT is profoundly interfering with the nervous circuits involved in the stimulation of food intake.

Thalamic interictal epileptiform discharges in deep brain stimulated epilepsy patients.

The relationships between interictal epileptiform discharges (IEDs) in the anterior (ANT) and dorsomedial nuclei (DMNT) of the thalamus and electro-clinical parameters in pharmacoresistant focal epilepsy patients receiving intrathalamic electrodes for deep brain stimulation (DBS) were investigated. Thalamus-localized IEDs (LIEDs) and surface EEG (sEEG)-IEDs were evaluated in eight patients who underwent ANT-DBS. Occurrence and frequency of ANT- and DMNT-LIEDs and pre-operative sEEG-IEDs were examined with respect to seizure onset location and seizure outcome following ANT-DBS. LIEDs were identified in all eight patients, in the ANT, DMNT, or both. ANT-LIEDs were observed in all patients with an unequivocal temporal seizure onset zone. The ANT-LIED frequency correlated with pre-surgical sEEG-IED frequency (ρ = 0.76, p = 0.033) and predicted ANT-DBS responsiveness (T = -2.6; p = 0.0428). Of the five patients with bilateral sEEG-IEDs, all had ANT-LIEDs, but only one patient had DMNT-LIEDs. All patients with no or unilateral sEEG-IEDs had DMNT-LIEDs. Observation of LIEDS in the ANT and DMNT supports the hypothesis that these nuclei are involved in propagation of focal epileptic activity. Their correspondence with differing electro-clinical features suggests that these nuclei are functionally distinguishable nodes within the epileptic networks of individual patients.

Neonatal overnutrition causes early alterations in the central response to peripheral ghrelin.

OBJECTIVE: Excess nutrient supply and rapid weight gain during early life are risk factors for the development of obesity during adulthood. This metabolic malprogramming may be mediated by endocrine disturbances during critical periods of development. Ghrelin is a metabolic hormone secreted from the stomach that acts centrally to promote feeding behavior by binding to growth hormone secretagogue receptors in the arcuate nucleus of the hypothalamus. Here, we examined whether neonatal overnutrition causes changes in the ghrelin system. METHODS: We used a well-described mouse model of divergent litter sizes to study the effects of postnatal overfeeding on the central and peripheral ghrelin systems during postnatal development. RESULTS: Mice raised in small litters became overweight during lactation and remained overweight with increased adiposity as adults. Neonatally overnourished mice showed attenuated levels of total and acyl ghrelin in serum and decreased levels of Ghrelin mRNA expression in the stomach during the third week of postnatal life. Normalization of hypoghrelinemia in overnourished pups was relatively ineffective at ameliorating metabolic outcomes, suggesting that small litter pups may present ghrelin resistance. Consistent with this idea, neonatally overnourished pups displayed an impaired central response to peripheral ghrelin. The mechanisms underlying this ghrelin resistance appear to include diminished ghrelin transport into the hypothalamus. CONCLUSIONS: Early postnatal overnutrition results in central resistance to peripheral ghrelin during important periods of hypothalamic development. Because ghrelin signaling has recently been implicated in the neonatal programming of metabolism, these alterations in the ghrelin system may contribute to the metabolic defects observed in postnatally overnourished mice.

Distribution and characterisation of Glucagon-like peptide-1 receptor expressing cells in the mouse brain.

OBJECTIVE: Although Glucagon-like peptide 1 is a key regulator of energy metabolism and food intake, the precise location of GLP-1 receptors and the physiological relevance of certain populations is debatable. This study investigated the novel GLP-1R-Cre mouse as a functional tool to address this question. METHODS: Mice expressing Cre-recombinase under the Glp1r promoter were crossed with either a ROSA26 eYFP or tdRFP reporter strain to identify GLP-1R expressing cells. Patch-clamp recordings were performed on tdRFP-positive neurons in acute coronal brain slices from adult mice and selective targeting of GLP-1R cells in vivo was achieved using viral gene delivery. RESULTS: Large numbers of eYFP or tdRFP immunoreactive cells were found in the circumventricular organs, amygdala, hypothalamic nuclei and the ventrolateral medulla. Smaller numbers were observed in the nucleus of the solitary tract and the thalamic paraventricular nucleus. However, tdRFP positive neurons were also found in areas without preproglucagon-neuronal projections like hippocampus and cortex. GLP-1R cells were not immunoreactive for GFAP or parvalbumin although some were catecholaminergic. GLP-1R expression was confirmed in whole-cell recordings from BNST, hippocampus and PVN, where 100 nM GLP-1 elicited a reversible inward current or depolarisation. Additionally, a unilateral stereotaxic injection of a cre-dependent AAV into the PVN demonstrated that tdRFP-positive cells express cre-recombinase facilitating virally-mediated eYFP expression. CONCLUSIONS: This study is a comprehensive description and phenotypic analysis of GLP-1R expression in the mouse CNS. We demonstrate the power of combining the GLP-1R-CRE mouse with a virus to generate a selective molecular handle enabling future in vivo investigation as to their physiological importance.

SOCS3 deficiency in leptin receptor-expressing cells mitigates the development of pregnancy-induced metabolic changes.

OBJECTIVE: During pregnancy, women normally increase their food intake and body fat mass, and exhibit insulin resistance. However, an increasing number of women are developing metabolic imbalances during pregnancy, including excessive gestational weight gain and gestational diabetes mellitus. Despite the negative health impacts of pregnancy-induced metabolic imbalances, their molecular causes remain unclear. Therefore, the present study investigated the molecular mechanisms responsible for orchestrating the metabolic changes observed during pregnancy. METHODS: Initially, we investigated the hypothalamic expression of key genes that could influence the energy balance and glucose homeostasis during pregnancy. Based on these results, we generated a conditional knockout mouse that lacks the suppressor of cytokine signaling-3 (SOCS3) only in leptin receptor-expressing cells and studied these animals during pregnancy. RESULTS: Among several genes involved in leptin resistance, only SOCS3 was increased in the hypothalamus of pregnant mice. Remarkably, SOCS3 deletion from leptin receptor-expressing cells prevented pregnancy-induced hyperphagia, body fat accumulation as well as leptin and insulin resistance without affecting the ability of the females to carry their gestation to term. Additionally, we found that SOCS3 conditional deletion protected females against long-term postpartum fat retention and streptozotocin-induced gestational diabetes. CONCLUSIONS: Our study identified the increased hypothalamic expression of SOCS3 as a key mechanism responsible for triggering pregnancy-induced leptin resistance and metabolic adaptations. These findings not only help to explain a common phenomenon of the mammalian physiology, but it may also aid in the development of approaches to prevent and treat gestational metabolic imbalances.

Brain-derived neurotrophic factor is required for axonal growth of selective groups of neurons in the arcuate nucleus.

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) is a potent regulator of neuronal development, and the Bdnf gene produces two populations of transcripts with either a short or long 3' untranslated region (3' UTR). Deficiencies in BDNF signaling have been shown to cause severe obesity in humans; however, it remains unknown how BDNF signaling impacts the organization of neuronal circuits that control energy balance. METHODS: We examined the role of BDNF on survival, axonal projections, and synaptic inputs of neurons in the arcuate nucleus (ARH), a structure critical for the control of energy balance, using Bdnf (klox/klox) mice, which lack long 3' UTR Bdnf mRNA and develop severe hyperphagic obesity. RESULTS: We found that a small fraction of neurons that express the receptor for BDNF, TrkB, also expressed proopiomelanocortin (POMC) or neuropeptide Y (NPY)/agouti-related protein (AgRP) in the ARH. Bdnf(klox/klox) mice had normal numbers of POMC, NPY, and TrkB neurons in the ARH; however, retrograde labeling revealed a drastic reduction in the number of ARH axons that project to the paraventricular hypothalamus (PVH) in these mice. In addition, fewer POMC and AgRP axons were found in the dorsomedial hypothalamic nucleus (DMH) and the lateral part of PVH, respectively, in Bdnf (klox/klox) mice. Using immunohistochemistry, we examined the impact of BDNF deficiency on inputs to ARH neurons. We found that excitatory inputs onto POMC and NPY neurons were increased and decreased, respectively, in Bdnf (klox/klox) mice, likely due to a compensatory response to marked hyperphagia displayed by the mutant mice. CONCLUSION: This study shows that the majority of TrkB neurons in the ARH are distinct from known neuronal populations and that BDNF plays a critical role in directing projections from these neurons to the DMH and PVH. We propose that hyperphagic obesity due to BDNF deficiency is in part attributable to impaired axonal growth of TrkB-expressing ARH neurons.

Adjusting the light in the limit conditions of consciousness by the means of ascending reticular activating system (ARAS) and of subordinated systems Part 1: Introduction and Aims.

BACKGROUND: In our activity in the Ambulance Service of Bucharest Municipality during March 2002 - March 2003 we studied a casuistry of patients who had fallen in a coma of varying degrees. To aid better understanding of coma, the concept of "pre-coma stage" or diencephalic "0 stage" was introduced. This concept complements the Arseni classification already used in medical practice, because some doctors alternatively use the term of "inaugural coma" for the same condition that we call diencephalic "0 stage". In the median hypothalamus and on the retino-hypothalamic path (SCN - AN) optical waves are transmitted, probably in the near infrared spectral range (800-1000 nm). These waves would constitute a means of transmitting information about the infradian biorhythm of coordination (frequencies below 1 cycle/28 hours), essential for the modulation and pre-processing of the consciousness and wakefulness, a fact which has already been demonstrated in animals. METHODS: The current work is based on observations made on a group of 51 patients with the precoma and coma conditions, and on a thorough study of the specialized (especially Romanian) literature. Also, we used validated scientific proof of torture in conditions of lack of light. RESULTS: We found a perfect interpenetration between the ARAS and the following two complementary subsystems: 1. The hypothalamic suprachiasmatic nucleus, that has the role of coordinating the periodicity of some biological functions depending on the circadian rhythm; and 2. The main photoperiodic organ, the pineal gland (epiphysis), which together with the ARAS has a role in the photoperiodicity modulation of some biological functions during the state of vigilance. CONCLUSION: From the above mentioned one may conclude that the consciousness condition is the unitary result of action of all human brain systems and especially sub-systems, which are controlled and led by a psycho-neurological process of integration at the cortex level. "Everyone knows what the consciousness is, until one tries to define it" (William James: The Stream of Consciousness", 1892).