18 entries found for : it-47
Xu L, Füredi N, Lutter C, Geenen B, Pétervári E, Balaskó M, Dénes Á, Kovács KJ, Gaszner B, Kozicz T (2022) Leptin coordinates efferent sympathetic outflow to the white adipose tissue through the midbrain centrally-projecting Edinger-Westphal nucleus in male rats. Neuropharmacology 205:108898. doi: 10.1016/j.neuropharm.2021.108898
Objective: To show that leptin bound to neurons of the Edinger-Westphal nucleus (EWcp) stimulated STAT3 phosphorylation and increases urocortin 1 (Ucn1)-production in a time-dependent manner.
Summary: EWcp/LepRb/Ucn1 neurons respond to leptin signaling as well as control white adipose tissue size and fat metabolism without altering food intake.
Usage: Ablation of EWcp leptin receptor (LepRb) positive neurons with leptin-saporin. Either unconjugated saporin (53 ng in 80 nl MQ, or Leptin-SAP (90 ng in 80 nl MQ, was injected into the rat midbrain.
Ujvári B, Pytel B, Márton Z, Bognár M, Kovács LÁ, Farkas J, Gaszner T, Berta G, Kecskés A, Kormos V, Farkas B, Füredi N, Gaszner B (2022) Neurodegeneration in the centrally-projecting Edinger-Westphal nucleus contributes to the non-motor symptoms of Parkinson's disease in the rat. J Neuroinflammation 19(1):31. doi: 10.1186/s12974-022-02399-w
Objective: To investigate whether neuron loss and alpha-synuclein accumulation in the urocortin 1 containing (UCN1) cells of the centrally-projecting Edinger-Westphal (EWcp) nucleus is associated with anxiety and depression-like state in the rat.
Summary: Neurodegeneration of urocortinergic EWcp contributes to the mood-related non-motor symptoms in toxic models of Parkinson's disease in the rat.
Usage: Leptin-SAP or unconjugated Saporin (0.08 μl) was injected into the EWcp area. This selective ablation of UCN1 neurons was used to validate the depression-like phenotype in rats. Behavioral, functional–morphological, biochemical and histopathological tools were used to test the motor coordination, mood status as well as morphological changes in the brain.
Cano G, Hernan SL, Sved AF (2021) Centrally projecting edinger-westphal nucleus in the control of sympathetic outflow and energy homeostasis. Brain Sci 11(8):1005. doi: 10.3390/brainsci11081005
Objective: To test the hypothesis that Edinger-Westphal nucleus (EWcp) integrates multimodal signals (stress, thermal, metabolic, endocrine, etc.) and modulates the sympathetic output simultaneously to multiple effector organs to maintain energy homeostasis under different conditions that require adjustments of energy demands.
Summary: Besides its role in feeding/metabolic control and addiction, EWcp is involved in several important functions that are ultimately related to different aspects of stress responses, as well as stress coping and adaptation.Leptin-SAP (Cat. #IT-47)
Harris RBS (2020) Loss of leptin receptor-expressing cells in the hindbrain decreases forebrain leptin sensitivity. Am J Physiol Endocrinol Metab 318(5):E806-E816. doi: 10.1152/ajpendo.00020.2020
Objective: This study tested whether loss of hindbrain leptin receptor signaling changed sensitivity to forebrain leptin.
Summary: Loss of VMH (ventromedial nucleus of hippocampus) leptin receptor-expressing cells prevents weight loss. The integrated response between the hindbrain and forebrain is heavily dependent upon leptin activity in the VMH.
Usage: To test forebrain leptin sensitivity Leptin-SAP and Blank-SAP rats received third ventricle injections of 0, 0.05, 0.1, 0.25 or 0.5 μg leptin.Related Products: Leptin-SAP (Cat. #IT-47), Blank-SAP (Cat. #IT-21)
Harris RB (2019) Leptin receptor activity in the nucleus of the solitary tract increases forebrain leptin sensitivity. Neuroscience 2019 Abstracts 591.04. Society for Neuroscience, Chicago, IL.
Summary: We previously reported that fourth ventricle infusions of leptin that cause weight loss are associated with an increase in hypothalamic phosphorylation of signal transducer and activator of transcription 3 (pSTAT3), a marker of leptin receptor (ObRb) activation, implying an integrated response to central leptin. This study tested the impact of ObRb activity in the nucleus of the solitary tract (NTS) on sensitivity to leptin in the forebrain. Leptin-Saporin (Lep-Sap) injections were used to delete ObR- expressing neurons in the NTS of 300g male Sprague Dawley rats. Controls were injected with Blank-Saporin (Blk-Sap). Loss of NTS ObR was confirmed with RNAScope in situ hybridization and pSTAT3 response to peripheral leptin in representative Lep- Sap rats. Experimental rats were fitted with 3rd ventricle (3V) guide cannula 12 days after Lep-Sap or Blk-Sap injections. Nine days later cannula placement was tested with Angiotensin II and rats were adapted to calorimeter cages for 4 days. Lep-Sap had no effect on body weight. To test leptin responsiveness rats were food deprived for 5 hours and at 5 p.m. they received 3V injections of 0, 0.05, 0.1, 0.25 or 0.5 μg leptin. Food was returned at 6 p.m., the start of the dark period. Each rat received the injections in random order at 4 day intervals. At the end of the experiment NTS pSTAT3 was used to confirm effcacy of Lep-Sap injections. Seven Lep-Sap and 6 control Blk-Sap rats completed the experiment. There was a dose-dependent inhibition of food intake in Blk-Sap rats, but only 0.5 μg leptin inhibited intake of Lep-Sap rats. Intake was inhibited during the 24 hours following injection and was not compensated for so that cumulative intake was inhibited for 60 hours post-injection. Energy expenditure was not different between groups and respiratory exchange ratio tended to follow food intake. These data suggest that leptin- induced inhibition of food intake is mediated by an integrated network involving both the forebrain and hindbrain and that activation of NTS ObRb lowers the threshold for leptin responsiveness in the forebrain.
Related Products: Leptin-SAP (Cat. #IT-47)
Seamon M, Ahn W, Li AJ, Ritter S, Harris RBS (2019) Leptin receptor-expressing neurons in ventromedial nucleus of the hypothalamus contribute to weight loss caused by fourth ventricle leptin infusions. Am J Physiol Endocrinol Metab 317(4):E586-E596. doi: 10.1152/ajpendo.00205.2019
Objective: To test the importance of VMH leptin responsiveness in mediating weight loss caused by fourth ventricle leptin infusion.
Summary: Leptin did not inhibit food intake and respiratory exchange ratio in rats treated with Leptin-SAP. VMH leptin receptors do not play a significant role in maintaining energy balance in basal conditions, but limit weight gain during positive energy balance.
Usage: Bilateral VMH 75-nl injections of 260 ng/ml of Leptin-SAP or Blank-SAP.Related Products: Leptin-SAP (Cat. #IT-47), Blank-SAP (Cat. #IT-21)
Challet E (2017) Circadian aspects of adipokine regulation in rodents. Best Practice & Research Clinical Endocrinology & Metabolism 31:573-582. doi: 10.1016/j.beem.2017.09.003
Summary: This paper reviews reciprocal links between the circadian clocks and rhythmic secretion of leptin, and discusses the metabolic impact of circadian desynchronization and altered rhythmic leptin. The authors report that leptin is well-known to modulate the timing of food intake by its anorectic effects mostly mediated by the arcuate nuclei of the hypothalamus. They cite a report by Li et al. demonstrating damage to the arcuate neurons expressing leptin receptors by local injections of Leptin-SAP (Cat. #IT-47) leads to hyperphagia coupled to arrhythmic pattern of feeding.
Related Products: Leptin-SAP (Cat. #IT-47)
Challet E, Kalsbeek A (2017) Editorial: Circadian Rhythms and Metabolism. Front Endocrinol (Lausanne) 8:201. doi: 10.3389/fendo.2017.00201
Related Products: Leptin-SAP (Cat. #IT-47)
Wiater MF, Li AJ, Dinh TT, Jansen HT, Ritter S (2013) Leptin-sensitive neurons in the arcuate nucleus integrate activity and temperature circadian rhythms and anticipatory responses to food restriction. Am J Physiol Regul Integr Comp Physiol 305(8):R949-R960. doi: 10.1152/ajpregu.00032.2013
Summary: The arcuate nucleus (Arc) of the hypothalamus is known to participate in the regulation of feeding, adiposity, and leptin-dependent metabolism. The authors examined the role of leptin-receptive neurons in locomotor and temperature rhythms. Rats received four bilateral injections of Leptin-SAP (Cat. #IT-47) into the Arc; Blank-SAP (Cat. #IT-21) was used as a control. The lesion affected learning connected to light cycles, but not learning connected to food schedules, suggesting a mechanism for internal desynchrony that might play a role in obesity and other metabolic disorders.
Xu L, Scheenen WJ, Roubos EW, Kozicz T (2012) Peptidergic Edinger-Westphal neurons and the energy-dependent stress response. Gen Comp Endocrinol 177(3):296-304. doi: 10.1016/j.ygcen.2011.11.039
Objective: This study investigates the role of the midbrain Edinger–Westphal centrally projecting neuron population (EWcp; synonym: non-preganglionic Edinger–Westphal nucleus) in the energy-dependent stress adaptation response.
Summary: The current data indicates that the EWcp receives information about stressors and peripheral metabolic status, and responds to this information by generating various neuropeptide messengers.
Usage: Leptin-SAP was injected into the EWcp, to kill Leptin receptor-positive neurons. With this approach ~50% of the Ucn1/CART neurons of the EWcp were lost, and the weights of both brown and white adipose tissue significantly increased.
Related Products: Leptin-SAP (Cat. #IT-47)
Li AJ, Wiater MF, Oostrom MT, Smith BR, Wang Q, Dinh TT, Roberts BL, Jansen HT, Ritter S (2012) Leptin-sensitive neurons in the arcuate nuclei contribute to endogenous feeding rhythms. Am J Physiol Regul Integr Comp Physiol 302(11):R1313-26. doi: 10.1152/ajpregu.00086.2012
Summary: It is clear that the arcuate nucleus (Arc) plays an important role in the generation of feeding rhythms. To clarify how this region modulates signals governing food intake the authors took advantage of the Arc mediation of leptin. Rats received bilateral injections of leptin-SAP (Cat. #IT-47, 56.5 ng per dose) into each Arc. Blank-SAP (Cat. #IT-21) was used as a control. The lesioned animals quickly became obese and displayed arrhythmic eating patterns under normal light conditions. The results indicate that lesioned neurons in the Arc as well as those in the suprachiasmatic nuclei are required for maintenance of feeding rhythms controlled by photic cues.
Kozicz T, Xu L, Geenen B, Gaszner B, Kovacs K, Roubos E (2011) Leptin-receptor-expressing neurons in the non-preganglionic Edinger-Westphal nucleus regulate white and brown adipose tissue. Neuroscience 2011 Abstracts 822.19. Society for Neuroscience, Washington, DC.
Summary: Leptin, produced by white adipose tissue (WAT), is a key factor that regulates food intake and energy expenditure in vertebrates. It conveys information about fat storage in the periphery to the brain. The leptin receptor long form (LepRb) can be found in the non-preganglionic Edinger-Westphal nucleus (npEW) in the midbrain, which is the main site of urocortin 1 (Ucn1) production in the brain. In both mice and rats, intraperitoneal administration of leptin induces an increase in Ucn1 expression in the npEW whereas in mice that lack LepRb (db/db mice), the npEW contains considerably reduced amount of Ucn1. The npEW also responds to acute thermal exposure, indicating a role of this nucleus in thermoregulation. Brown adipose tissue (BAT) is critical to maintain homoeothermia and is centrally controlled via sympathetic outputs. A recent study demonstrates a projection from EW to BAT by using retrograde tracer pseudorabies virus (PRV). In our study, using PRV injection into the WAT of rats, we identified PRV-labeled Ucn1 neurons in the npEW, indicating a connection from npEW to WAT. In order to analyze the involvement of the npEW in the regulation of sympathetic WAT and BAT outputs, we performed the experiment using the neurotoxin saporin. When conjugated to leptin (Lep-SAP), Lep-SAP can selectively kill LepRb-expressing neurons. Wister rats were given injection of either Lep-SAP or a control blank saporin (B-SAP) into the left npEW Results showed that injection of Lep-SAP significantly blunted Ucn1 expression in the npEW. The weights of WAT and BAT were analyzed on both sides. The WAT and BAT weights were increased significantly on the contralateral side in Lep-SAP compared with B-SAP injected rats, however not different on the ipsilateral side. Interestingly, we observed that both WAT and BAT weighed more on the ipsilateral than the contralateral side only in the B-SAP animals. We will further test the effect of lesioning npEW neurons on the function of WAT and BAT by assessing specific WAT and BAT markers by RT-PCR and histology. Taken these data together, we provide evidence that LepRb-expressing neurons in the npEW regulate BAT and WAT most probably via sympathetic circuits.
Dinh TT, Smith BR, Wiater MF, Jansen H, Li A-J, Ritter S (2011) Lesions targeting leptin-sensitive neurons in the ventromedial and suprachiasmatic nuclei differentiate sites for circadian control of feeding. Neuroscience 2011 Abstracts 600.13. Society for Neuroscience, Washington, DC.
Summary: We have previously investigated the role of leptin sensitive networks in the mediobasal hypothalamus (MBH) for feeding using the saporin toxin conjugated to leptin (Lep-SAP) and a control conjugate, blank-saporin (B-SAP). Lep-SAP binds to, is internalized by and destroys leptin receptor expressing neurons at the injection site. We found that injections of Lep-SAP directed at the arcuate nuclei (Arc) caused profound regulatory and circadian deficits including arrhythmia for feeding. We have proposed that leptin-sensitive circuitry within the MBH, particularly the arcuate nuclei (Arc), is required for the maintenance of feeding rhythms. Here we tested this hypothesis further by examining effects of Lep-SAP injections into two additional hypothalamic nuclei in the vicinity of the Arc, the ventromedial nucleus (VMN) and the suprachiasmatic nucleus (SCN). In an additional group, the SCN was lesioned electrolytically. Feeding data were collected using BioDAQ computerized meal monitors (Research Diets, Inc) and analyzed using ClockLab software to generate double raster eatogram plots. Lomb-Scargle periodograms were used to assess rhythms and their robustness. Feeding was monitored under light:dark (LD) and dark:dark (DD) conditions in all groups except SCN Lep-SAPs. Unlike Arc-directed injections of Lep-SAP, VMN injections did not alter the diurnal distribution of feeding in either LD or DD and lesioned rats did not become obese or hyperphagic. Lomb-Scargle analysis and eatograms indicated that VMN rats have intact circadian rhythms for feeding. Both Lep-SAP and electrolytic lesions of the SCN caused a slight reduction body weight, compared to controls. Total 24h food intake was unchanged, but light-period food intake was increased. Rats with electrolytic lesions of the SCN were arrhythmic for feeding under both LD and DD conditions. Together with results from Arc Lep-SAP injections, these findings strongly implicate leptin-sensitive circuitry in the MBH in control of circadian feeding rhythms. In addition, they point to the particular significance of the Arc and its connections with the SCN in this circuitry. Leptin-sensitive neurons in the VMN appear to be of less importance in this role.
Related Products: Leptin-SAP (Cat. #IT-47)
Wiater MF, Jansen H, Oostrom M, Li A-J, Dinh T, Ritter S (2011) Lesions targeting leptin-sensitive neurons in the mediobasal hypothalamus dissociate activity and temperature circadian rhythms. Neuroscience 2011 Abstracts 396.11. Society for Neuroscience, Washington, DC.
Summary: Previously we investigated the role of NPY and leptin sensitive networks in the mediobasal hypothalamus in sleep and feeding and found profound regulatory and circadian deficits. We propose that the MBH, particularly the arcuate nuclei (Arc), is required for the integration of homeostatic circadian systems including temperature and activity. We tested this hypothesis with the use of the saporin toxin conjugated to leptin (Lep-SAP) or a blank molecule with no known biological function or receptor (B-SAP) directed to the Arc. Lep-SAP binds to, is internalized by and destroys leptin receptor expressing neurons at the injection site. Lep-SAP rats became obese and hyperphagic and progressed through a dynamic phase to a static phase of growth similar to a ventromedial lesioned rat. Activity and temperature data were collected using intraperitoneal PDT-4000 Emitters with Vital View Data Acquisition Software (Mini Mitter, Philips Respironics, Bend, OR). Circadian rhythms were examined over 49 days during the static phase of obesity in B-SAP (n=10) and Lep-SAP (n=12) rats. Rats were maintained on a 12:12 light:dark (LD) schedule for 13 days and thereafter maintained in continuous dark (DD). After the first thirteen days of DD, food was restricted to four hours per day from 9AM until 1PM for ten days. Immediately thereafter, rats were fasted for three days to evaluate persistence of food-entrained rhythms. Using ClockLab software (Natick, MA) actograms and tempograms were generated as double raster plots. Lomb-Scargle periodograms were used to assess rhythms and their robustness. We found that Lep-SAP rats were arrhythmic for activity in DD, but that food anticipatory activity was nevertheless entrainable to the restricted feeding schedule and the entrained rhythm persisted during the subsequent 3-day fast. Thus, for activity, the light-entrainable oscillator, but not the food entrainable oscillator, was disabled by the MBH lesion. In contrast, temperature remained rhythmic in DD in the Lep-SAP rats, but did not entrain to restricted feeding. We conclude that the leptin-sensitive network of the Arc and MBH is required for entrainment of activity by photic cues and for entrainment of temperature by food and for the integration of these rhythms.
Wiater MF, Oostrom M, Barfield R, Dinh TT, Li A-J, Ritter S (2010) Leptin-saporin lesions of the arcuate nucleus induce an arrhythmic circadian feeding pattern. Neuroscience 2010 Abstracts 733.6. Society for Neuroscience, San Diego, CA.
Summary: The endogenous circadian rhythm of feeding is incompletely understood. The leptin sensitive network within the arcuate nucleus (Arc) of the hypothalamus is important for the control of feeding. Genetic deletion of leptin or leptin receptors results in profound obesity, hyperphagia, and the loss of day/night differences in food intake. Because the Arc is critically involved in control of food intake and contains leptin receptors, we hypothesized that the Arc plays an important role in maintenance of feeding rhythms. To examine this hypothesis, we injected a newly developed targeted toxin, leptin conjugated to saporin (LSAP), into the Arc to lesion leptin receptor-expressing neurons in the vicinity of the injection. Controls were injected saporin conjugated to a peptide with no known action or receptor (blank-saporin, BSAP). We expected the Arc LSAP would disrupt the circadian rhythm of food intake, as seen in rats with genetic deletion of leptin or its receptor. Eating rhythms were monitored continuously (each minute) over a 60-day period using BioDAQ (Research Diets) automated meal monitoring equipment. Data were analyzed for circadian rhythm using ClockLab (ActiMetrics) software. Eatograms (food intake in actogram format), showing eating times and durations comparable to actograms used for wheel-running activity, and Chi-square periodograms were generated. Feeding was monitored in light:dark, dark:dark, or light:light conditions. The LSAP injection caused profound hyperphagia, weight gain and disrupted circadian feeding patterns. Although LSAP rats remained sensitive to light and dark under certain circumstances and were capable of an apparent rhythm during light:dark conditions, feeding was arrhythmic by all measures when photic cues were removed (i.e., in dark:dark and light:light conditions). At the end of experimentation, lesions were analyzed using immunohistochemistry to detect agouti gene related protein (AGRP) and α-melanocortin stimulating hormone (α-MSH) neurons, both known to express leptin receptors. Cell bodies positive for these peptides were greatly diminished in the Arc. Results indicate that the Arc contributes importantly to the expression of circadian rhythms of food intake.
Li A-J, Dinh TT, Wang Q, Wiater MF, Ritter S (2010) Leptin-saporin lesion of hypothalamic arcuate neurons impairs circadian feeding rhythms. Neuroscience 2010 Abstracts 498.6/III29. Society for Neuroscience, San Diego, CA.
Summary: To examine the role of leptin receptor-expressing neurons in the arcuate nucleus (Arc) in circadian control of spontaneous feeding and energy expenditure, we injected a novel targeted toxin, leptin conjugated to saporin (Lep-SAP) into the Arc in rats. Lep-SAP effectively lesioned Arc neurons in a leptin-receptor dependent manner, indicated by an 80% reduction of agouti gene-related protein- or melanocyte-stimulating hormone-immunoreactive neurons in Sprague Dawley rats, but not in leptin receptor deficient Zucker fa/fa rats. Food intake and metabolism were monitored 3-5 weeks after Arc Lep-SAP and control blank-saporin (B-SAP) injections using an Oxymax system. Lep-SAP rats consumed 49% of their total daily intake during the day, compared to 34% in B-SAP rats. Eatograms (feeding actograms), cosinar analysis and Chi-square periodograms of continuous feeding records failed to detect a circadian oscillation in the feeding patterns of Lep-SAP rats, but did detect significant circadian rhythms in B-SAP controls. Unlike feeding, metabolic rate, respiratory exchange ratio and locomotor activity continued to exhibit significant circadian periodicity in both groups, though dampened in amplitude in Lep-SAPs, suggesting that rhythms of feeding and metabolism may be controlled by separate mechanisms. Expression of clock-related genes (Per1 and Bmal1) in hypothalamus, liver and white fat tissue was asynchronous in Lep-SAP rats. These results suggest that leptin-receptive neurons in the Arc exert a critical influence on the circadian patterning of food intake.
Related Products: Leptin-SAP (Cat. #IT-47)
Li AJ, Wang Q, Dinh TT, Ritter S (2010) Featured Article: Deletion of NPY/AGRP and POMC neurons in the arcuate nucleus by leptin-saporin produces hyperphagia, obesity and changes in diurnal feeding patterns in rats. Targeting Trends 11(1)
Li A-J, Wang Q, Dinh TT, Ritter S (2009) Leptin-saporin injection into the arcuate nucleus lesions NPY/AGRP and POMC neurons and produces hyperphagia, obesity and changes in diurnal feeding patterns in rats. Neuroscience 2009 Abstracts 374.5/EE116. Society for Neuroscience, Chicago, IL.
Summary: Leptin-saporin (Lep-SAP), a conjugate of leptin with a ribosomal inactivating toxin, saporin (Advanced Targeting Systems), is a novel toxin designed to destroy leptin receptor-expressing cells selectively in vitro. However, its lesioning properties in vivo are currently unknown. Here, we injected Lep-SAP into the arcuate nucleus (Arc), to examine its effects on feeding behavior and on leptin receptor-expressing NPY/AGRP and POMC neurons in this area. Immunohistochemical studies showed unilateral injection of Lep-SAP into the Arc dramatically reduced numbers of NPY-Y1- and α-MSH- positive neurons compared to the contralateral side injected with SAP control. Real-time PCR revealed only 11-21% of Agrp and Pomc expression remaining in the Arc after Lep-SAP injection into this region. Rats injected bilaterally with Lep-SAP were unresponsive to central leptin administration and showed dramatic increases in feeding, body weight and light-phase feeding, compared pre-injection baseline. Two weeks after injection, total daily feeding was increased by 75%, light phase feeding by 359% and dark phase feeding by 33%. Control SAP injections did not produce these changes. Clock gene expression in homogenates of whole hypothalamus and liver were quantified at ZT 5-7. Bmal1 expression in hypothalamus and liver of Lep-SAP rats was decreased, while hepatic Per1 expression was increased compared to control. Results demonstrate that Lep-SAP effectively lesions Arc leptin receptor-expressing NPY/AGRP and POMC neurons in vivo, and that rats with this lesion are hyperphagic and obese, possibly due to enhanced hunger drive, lack of responsiveness to leptin and/or changes in circadian control of feeding behavior.