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Oxytocin receptor-deficient mice showed dysfunction of the thermoregulatory ability
Abstracts / Neuroscience Research 71S (2011) e108–e415
we have reported that the dorsal motor nucleus of the vagus nerve (DMV) contains many MC4R-expressing neurons that project to the stomach and duodenum. In the present study, we examined whether or not the MC4R-expressing DMV neurons send their axons to enteric ganglia neurons of the MC4R/GFP mouse. Using whole mount preparation, we showed that numerous GFP-immunoreactive axons forming net-like structures with bouton-like varicosities were distributed throughout the myenteric plexus of the stomach and duodenum. After in vivo treatment of colchicine, we also demonstrated that GFP-immunoreactive bouton-like varicosities were closely apposed to the ganglionic neurons, some of which showed immunoreactivity for vasoactive intestinal polypeptide, one of the postganglionic cell makers in the enteric ganglia. Using preembedding immunolabeling technique, we revealed that many GFP-immunoreactive axonal profiles containing both large dense-cored vesicles and small clear vesicles surrounded the ganglionic neurons in the myenteric plexus of the stomach and duodenum. Furthermore, some of these GFP-immunoreactive axonal profiles made synaptic contacts predominantly with somatic profiles and additionally with dendritic profiles of the ganglionic neurons. These results suggest that the MC4R-expressing DMV neurons send their axons to the enteric ganglia for the control of gastrointestinal motility and secretion. doi:10.1016/j.neures.2011.07.702
P2-l17 Modulation of sweet sensitivity by endogenous leptin and endocannabinoid Mayu Niki , Masafumi Jyotaki, Tadahiro Ohkuri, Ryusuke Yoshida, Yuzo Ninomiya Oral Neurosci., Grad. Sch. Dental Sci., Kyushu Univ., Fukuoka, Japan The taste organ is a peripheral target for both leptin (Lep), an anorexic mediator and endocannabinoids (EDs), orexigenic mediators. In mice, Lep selectively inhibits behavioral, taste nerve and taste cell responses to sweet compounds. Opposing the action of Lep, EDs enhance the sweet taste responses. Such modulation disappeared in db/db mice with defects in Lep receptors or mice genetically lacking ED receptors, suggesting that exogeneous Lep or EDs affects sweet taste via activation of their cognate receptors in taste cells. However, potential roles of endogenous Lep and EDs in sweet taste remain unclear. Here, we examined effects of antagonists for Ob–Rb (L39A/D40A/F41A) Lep and CB1 (AM251) ED receptors on the chorda tympani (CT) nerve responses in lean control and db/db mice. The results demonstrated that lean mice exhibited significant increases in CT responses to sweet compounds after i.p. administration of L39A/D40A/F41A, while they showed no significant changes in the CT responses after AM251. In contrast, db/db mice showed clear suppression of CT responses to sweet compounds after AM251, and exhibited enhanced expression of a biosynthesizing enzyme (DAGL) of ED in taste cells. These findings suggest a possibility that circulating Lep may act as a modulator in lean mice that tonically affects basal sweet sensitivity, whereas EDs whose production may be potentiated under defects in the Lep system, may lead to increased basal sweet sensitivity in Lep receptor-deficient db/db mice. doi:10.1016/j.neures.2011.07.703
P2-l18 Oxytocin receptor-deficient mice showed dysfunction of the thermoregulatory ability Keisuke Sato 1 , Yoshiyuki Kasahara 1 , Hiroaki Mizukami 2 , Katsuhiko Nishimori 1 1
Lab. of Mol. Biol., Grad. Sch. of Agric. Sci., Tohoku Univ., Sendai, Japan 2 Div. of Genetic Therapeutics, Cent. for Mol. Med., Jichi Medical Univ, Simotsuke, Japan We recently showed that oxytocin receptor-deficient (Oxtr −/−) male mice exhibited late-onset obesity. They had also deficit in maintaining their body temperature during exposure to cold environment. Histological sections of brown adipose tissue (BAT), which generated heat to control the body temperature, from Oxtr −/− mice showed a number of adipocytes filled with large lipid droplets and a marked decrease in multilocular adipocytes, a typical feature of functionally inactive BAT. Both oxytocin (OXT) and OXTR genes were mainly expressed in the brain but not in mature brown adipocytes. With these evidences, we deduced that OXT/OXTR systems controlled the thermoregulation via central nervous system. Using c-Fos immunoreactivity as a marker of neuronal activation, Oxtr −/− mice showed decreases in c-Fos immunoreactivity in the dorsomedial hypothalamus (DMH) in cold exposure.Next we injected adeno-associated virus vector harboring Oxtr cDNA (AAV-Oxtr) into the DMH of Oxtr −/− mice, to rescue the expression of OXTR in a limited region. Interestingly, Oxtr −/− mice injected with AAV-
e163
Oxtr vector ameliorated the hypofunction of thermogenesis observed in Oxtr −/− mice compared with the mice injected with AAV-LacZ vector as a control. These results strongly suggested that the deficits of thermoregulation in Oxtr −/− mice could be caused by the absence of OXTR in the DMH, at least in part. Our study first demonstrates that the OXT/OXTR system plays important roles in the regulation of body temperature homeostasis. doi:10.1016/j.neures.2011.07.704
P2-l19 Regulation of the body temperature by oxytocin receptor/serotonin pathway Yuko Tateishi 1 , Keisuke Sato 1 , Yoshiyuki Kasahara 1 , Hiroaki Mizukami 2 , Katsuhiko Nishimori 1 1 Lab. of Molecular Biology, Graduate School of Agricultural Science, Tohoku Univ, Sendai 2 Div. of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical Univ, Shimothuke
Oxytocin (OXT) is a nonapeptide hormone, produced primarily in the paraventricular and supraoptic nuclei of the hypothalamus, and secreted into blood flow from posterior pituitary gland. Oxytocin receptor (OXTR) expresses widely in whole body. We generated OXTR deficient (Oxtr−/−) mice and found that some of their social behaviors were impaired. Interestingly, Oxtr−/− mice also displayed tendency of obesity, impaired body thermoregulation, and morphological defect in brown adipose tissue (BAT) of them. While, we reported that serotonin was released in the median raphe by the administration of OXT in the previous work. In that work, we also found the colocalization of OXTR and tryptophan hydroxylase 2 (TPH2), a serotonin synthetase, in the same neurons at the median and dorsal raphe nuclei. These results suggested that the release of serotonin were regulated by the OXT/OXTR system. As BAT was the organ for thermogenesis, and was under the control of the serotonin neurons in the raphe pallidus (RPa), so we hypothesized that the activation of BAT was modulated by the OXT–OXTR–serotonin pathway. To prove this hypothesis, we first analyzed the expression of OXTR in the RPa and confirmed its activation after the cold exposure. Next, we tested colocalization of OXTR and TPH2 in the same neurons in the RPa. These results suggested that OXT–OXTR–serotonin pathway might be functional for thermogeneration in the RPa. Finally we carried out the injection of adeno-associated viral vector harboring OXTR cDNA (AAV–Oxtr), into the RPa of Oxtr−/− mice, to generate the mice expressing OXTR only in the RPa. By exposure of them to cold, we confirmed that the thermoregulatory function in the mice injected with AAV–Oxtr was rescued. These experimental data strongly suggested that the thermogenesis in the BAT was modulated by OXT–OXTR–serotonin pathway. doi:10.1016/j.neures.2011.07.705
P2-l20 Projections from the anterior basomedial and anterior cortical nuclei of the amygdala to melaninconcentrating hormone-containing neurons in the lateral hypothalamus of the rat Jian-Guo Niu , Shigefumi Yokota, Toshiko Tsumori, Tatsuro Oka, Yukihiko Yasui Dept. of Anat. & Morphol. Neurosci., Shimane Univ. Sch. Med., Izumo, Japan Melanin-concentrating hormone (MCH) is involve in the regulation of feeding behavior as well as in goal oriented behaviors, and MCH-containing neurons are distributed mainly in the lateral hypothalamus (LH). The anterior basomedial nucleus (BMA) and anterior cortical nucleus (ACo) of the amygdala have been known to form part of a circuit involved in processing olfactory, gustatory and visceral information. The BMA–LH and ACo–LH pathways are suggested to be implicated in the control of feeding. However, it is still unknown whether or not MCH-containing LH neurons are under the direct influence of the BMA and ACo. Here the organization of projections from the BMA and ACo to MCH-containing LH neurons was examined. Using a retrograde tracer, cholera toxin B subunit (CTb), we first showed that both the BMA and the ACo contained numerous LH-projecting neurons. Using a combined anterograde tracing with biotinylated dextranamine (BDA) and immunohistochemistry for MCH, we secondly demonstrated that the distribution pattern of BMA fibers was similar to that of ACo fibers in the LH, and a prominent overlapping distribution of these fibers and MCH-immunoreactive (IR) neurons existed in the ventrolateral LH. We further revealed that asymmetrical synapses were made between these fibers and neurons. Using a combination of retrograde tract-tracing with CTb, immunohistochemistry for MCH and in situ hybridization for vesicular glutamate transporter 2 (VGLUT2) mRNA, we thirdly showed that most of the LH-projecting BMA and ACo neurons expressed VGLUT2 mRNA. Using a com-
we have reported that the dorsal motor nucleus of the vagus nerve (DMV) contains many MC4R-expressing neurons that project to the stomach and duodenum. In the present study, we examined whether or not the MC4R-expressing DMV neurons send their axons to enteric ganglia neurons of the MC4R/GFP mouse. Using whole mount preparation, we showed that numerous GFP-immunoreactive axons forming net-like structures with bouton-like varicosities were distributed throughout the myenteric plexus of the stomach and duodenum. After in vivo treatment of colchicine, we also demonstrated that GFP-immunoreactive bouton-like varicosities were closely apposed to the ganglionic neurons, some of which showed immunoreactivity for vasoactive intestinal polypeptide, one of the postganglionic cell makers in the enteric ganglia. Using preembedding immunolabeling technique, we revealed that many GFP-immunoreactive axonal profiles containing both large dense-cored vesicles and small clear vesicles surrounded the ganglionic neurons in the myenteric plexus of the stomach and duodenum. Furthermore, some of these GFP-immunoreactive axonal profiles made synaptic contacts predominantly with somatic profiles and additionally with dendritic profiles of the ganglionic neurons. These results suggest that the MC4R-expressing DMV neurons send their axons to the enteric ganglia for the control of gastrointestinal motility and secretion. doi:10.1016/j.neures.2011.07.702
P2-l17 Modulation of sweet sensitivity by endogenous leptin and endocannabinoid Mayu Niki , Masafumi Jyotaki, Tadahiro Ohkuri, Ryusuke Yoshida, Yuzo Ninomiya Oral Neurosci., Grad. Sch. Dental Sci., Kyushu Univ., Fukuoka, Japan The taste organ is a peripheral target for both leptin (Lep), an anorexic mediator and endocannabinoids (EDs), orexigenic mediators. In mice, Lep selectively inhibits behavioral, taste nerve and taste cell responses to sweet compounds. Opposing the action of Lep, EDs enhance the sweet taste responses. Such modulation disappeared in db/db mice with defects in Lep receptors or mice genetically lacking ED receptors, suggesting that exogeneous Lep or EDs affects sweet taste via activation of their cognate receptors in taste cells. However, potential roles of endogenous Lep and EDs in sweet taste remain unclear. Here, we examined effects of antagonists for Ob–Rb (L39A/D40A/F41A) Lep and CB1 (AM251) ED receptors on the chorda tympani (CT) nerve responses in lean control and db/db mice. The results demonstrated that lean mice exhibited significant increases in CT responses to sweet compounds after i.p. administration of L39A/D40A/F41A, while they showed no significant changes in the CT responses after AM251. In contrast, db/db mice showed clear suppression of CT responses to sweet compounds after AM251, and exhibited enhanced expression of a biosynthesizing enzyme (DAGL) of ED in taste cells. These findings suggest a possibility that circulating Lep may act as a modulator in lean mice that tonically affects basal sweet sensitivity, whereas EDs whose production may be potentiated under defects in the Lep system, may lead to increased basal sweet sensitivity in Lep receptor-deficient db/db mice. doi:10.1016/j.neures.2011.07.703
P2-l18 Oxytocin receptor-deficient mice showed dysfunction of the thermoregulatory ability Keisuke Sato 1 , Yoshiyuki Kasahara 1 , Hiroaki Mizukami 2 , Katsuhiko Nishimori 1 1
Lab. of Mol. Biol., Grad. Sch. of Agric. Sci., Tohoku Univ., Sendai, Japan 2 Div. of Genetic Therapeutics, Cent. for Mol. Med., Jichi Medical Univ, Simotsuke, Japan We recently showed that oxytocin receptor-deficient (Oxtr −/−) male mice exhibited late-onset obesity. They had also deficit in maintaining their body temperature during exposure to cold environment. Histological sections of brown adipose tissue (BAT), which generated heat to control the body temperature, from Oxtr −/− mice showed a number of adipocytes filled with large lipid droplets and a marked decrease in multilocular adipocytes, a typical feature of functionally inactive BAT. Both oxytocin (OXT) and OXTR genes were mainly expressed in the brain but not in mature brown adipocytes. With these evidences, we deduced that OXT/OXTR systems controlled the thermoregulation via central nervous system. Using c-Fos immunoreactivity as a marker of neuronal activation, Oxtr −/− mice showed decreases in c-Fos immunoreactivity in the dorsomedial hypothalamus (DMH) in cold exposure.Next we injected adeno-associated virus vector harboring Oxtr cDNA (AAV-Oxtr) into the DMH of Oxtr −/− mice, to rescue the expression of OXTR in a limited region. Interestingly, Oxtr −/− mice injected with AAV-
e163
Oxtr vector ameliorated the hypofunction of thermogenesis observed in Oxtr −/− mice compared with the mice injected with AAV-LacZ vector as a control. These results strongly suggested that the deficits of thermoregulation in Oxtr −/− mice could be caused by the absence of OXTR in the DMH, at least in part. Our study first demonstrates that the OXT/OXTR system plays important roles in the regulation of body temperature homeostasis. doi:10.1016/j.neures.2011.07.704
P2-l19 Regulation of the body temperature by oxytocin receptor/serotonin pathway Yuko Tateishi 1 , Keisuke Sato 1 , Yoshiyuki Kasahara 1 , Hiroaki Mizukami 2 , Katsuhiko Nishimori 1 1 Lab. of Molecular Biology, Graduate School of Agricultural Science, Tohoku Univ, Sendai 2 Div. of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical Univ, Shimothuke
Oxytocin (OXT) is a nonapeptide hormone, produced primarily in the paraventricular and supraoptic nuclei of the hypothalamus, and secreted into blood flow from posterior pituitary gland. Oxytocin receptor (OXTR) expresses widely in whole body. We generated OXTR deficient (Oxtr−/−) mice and found that some of their social behaviors were impaired. Interestingly, Oxtr−/− mice also displayed tendency of obesity, impaired body thermoregulation, and morphological defect in brown adipose tissue (BAT) of them. While, we reported that serotonin was released in the median raphe by the administration of OXT in the previous work. In that work, we also found the colocalization of OXTR and tryptophan hydroxylase 2 (TPH2), a serotonin synthetase, in the same neurons at the median and dorsal raphe nuclei. These results suggested that the release of serotonin were regulated by the OXT/OXTR system. As BAT was the organ for thermogenesis, and was under the control of the serotonin neurons in the raphe pallidus (RPa), so we hypothesized that the activation of BAT was modulated by the OXT–OXTR–serotonin pathway. To prove this hypothesis, we first analyzed the expression of OXTR in the RPa and confirmed its activation after the cold exposure. Next, we tested colocalization of OXTR and TPH2 in the same neurons in the RPa. These results suggested that OXT–OXTR–serotonin pathway might be functional for thermogeneration in the RPa. Finally we carried out the injection of adeno-associated viral vector harboring OXTR cDNA (AAV–Oxtr), into the RPa of Oxtr−/− mice, to generate the mice expressing OXTR only in the RPa. By exposure of them to cold, we confirmed that the thermoregulatory function in the mice injected with AAV–Oxtr was rescued. These experimental data strongly suggested that the thermogenesis in the BAT was modulated by OXT–OXTR–serotonin pathway. doi:10.1016/j.neures.2011.07.705
P2-l20 Projections from the anterior basomedial and anterior cortical nuclei of the amygdala to melaninconcentrating hormone-containing neurons in the lateral hypothalamus of the rat Jian-Guo Niu , Shigefumi Yokota, Toshiko Tsumori, Tatsuro Oka, Yukihiko Yasui Dept. of Anat. & Morphol. Neurosci., Shimane Univ. Sch. Med., Izumo, Japan Melanin-concentrating hormone (MCH) is involve in the regulation of feeding behavior as well as in goal oriented behaviors, and MCH-containing neurons are distributed mainly in the lateral hypothalamus (LH). The anterior basomedial nucleus (BMA) and anterior cortical nucleus (ACo) of the amygdala have been known to form part of a circuit involved in processing olfactory, gustatory and visceral information. The BMA–LH and ACo–LH pathways are suggested to be implicated in the control of feeding. However, it is still unknown whether or not MCH-containing LH neurons are under the direct influence of the BMA and ACo. Here the organization of projections from the BMA and ACo to MCH-containing LH neurons was examined. Using a retrograde tracer, cholera toxin B subunit (CTb), we first showed that both the BMA and the ACo contained numerous LH-projecting neurons. Using a combined anterograde tracing with biotinylated dextranamine (BDA) and immunohistochemistry for MCH, we secondly demonstrated that the distribution pattern of BMA fibers was similar to that of ACo fibers in the LH, and a prominent overlapping distribution of these fibers and MCH-immunoreactive (IR) neurons existed in the ventrolateral LH. We further revealed that asymmetrical synapses were made between these fibers and neurons. Using a combination of retrograde tract-tracing with CTb, immunohistochemistry for MCH and in situ hybridization for vesicular glutamate transporter 2 (VGLUT2) mRNA, we thirdly showed that most of the LH-projecting BMA and ACo neurons expressed VGLUT2 mRNA. Using a com-