Biology subjects

Iijima, N.

Publications and source records attributed to Iijima, N..

4 recordsLinked to original sources

bioRxiv2022

Expectation for sweet taste changes peripheral glucose metabolism via basolateral amygdala

Anticipatory physiological responses to food were first reported by Ivan Pavlov a century ago but the associated neural mechanism is still ill-defined. Here, we identified two types of neurons in the basolateral amygdala (BLA), which are activated by sweetener (saccharin) or water after sucrose conditioning, representing expected sweet taste and unmet expectation, respectively. Saccharin-induced met-expectation of sweet taste enhances, while H2O-induced unmet-expectation deteriorates, glucose metabolism in peripheral tissues. Deletion of saccharin-responsive neurons in BLA impaired saccharin-induced increase in insulin sensitivity. Deletion of H2O-responsive neurons in BLA improved glucose intolerance by unmet-expectation. Saccharin- and H2O-responsive neurons had different gene expressions. Our data suggest that the gap between the expected incoming sugar and sweet taste is evaluated by distinct BLA neurons to control peripheral glucose metabolism. One-Sentence SummaryNeurons in the basolateral amygdala control blood glucose levels by comparing anticipated sugar intake and sweet taste

physiology↗

bioRxiv2020

Activation of prodynorphin neurons in the dorsomedial hypothalamus inhibits food intake and promotes positive valence

The regulation of food intake is one of the major research areas in the study of metabolic syndromes such as obesity. Gene targeting studies have clarified the roles of hypothalamic neurons in feeding behaviour. However, our understanding of neural function under physiological conditions is still limited. Immediate early genes, such as activity-regulated cytoskeleton-associated protein (Arc/Arg3.1), are useful markers of neuronal activity. Here, we investigated the role of Arc/Arg3.1 gene-expressing neurons in the hypothalamus after refeeding using the targeted recombination in active populations method. We identified refeeding-responsive prodynorphin/cholecystokinin neurons in the dorsomedial hypothalamus that project to the paraventricular hypothalamic nucleus. Chemogenetic activation of these neurons decreased food intake and promoted positive valence. Our findings provide insight into the role of newly identified hedonic neurons in the process of feeding-induced satiety.

physiology↗

bioRxiv2020

Prostaglandin in the ventromedial hypothalamus regulates peripheral glucose metabolism

The hypothalamus plays a central role in monitoring and regulating systemic glucose metabolism. The brain is enriched with phospholipids containing poly-unsaturated fatty acids, which are biologically active in physiological regulation. Here, we show that intraperitoneal glucose injection induced changes in hypothalamic distribution and amount of phospholipids, especially arachidonic-acid-containing phospholipids, that were then metabolized to produce prostaglandins. Knockdown of cytosolic phospholipase A2 (cPLA2), a key enzyme for generating arachidonic acid from phospholipids, in the hypothalamic ventromedial nucleus (VMH), lowered insulin sensitivity in muscles during regular chow diet (RCD) feeding. Conversely, the down-regulation of glucose metabolism by high fat diet (HFD) feeding was improved by knockdown of cPLA2 in the VMH through changing hepatic insulin sensitivity and hypothalamic inflammation. Our data suggest that cPLA2-mediated hypothalamic phospholipid metabolism is critical for controlling systemic glucose metabolism during RCD, while continuous activation of the same pathway to produce prostaglandins during HFD deteriorates glucose metabolism.

physiology↗

bioRxiv2018

High prevalence of the antibody against Syncytin-1 in schizophrenia

Both genetic and environmental factors have been considered causative agents for schizophrenia (SZ). However, no single gene has been shown responsible for the development of SZ. Furthermore, the pathophysiological roles of environmental factors including psychological stress, autoimmunity, and microbial infection have not been fully understood. Previous studies have suggested the involvement of one of the human endogenous retroviruses (HERVs), HERV-W, in SZ. In this study, prevalence of antibodies against the HERV-W Syncytin-1 protein was examined using a newly developed ELISA test. Fifty percent of patients with SZ (24 out of 48 cases) were antibody-positive, with a specificity of greater than 95% (less than 5% of control cases, 3 out of 79). No significant effect of medication was evident, nor did any SZ cases become seropositive after diagnosis. These findings indicate a possible involvement of HERV-W expression in the development of SZ and support its applicability to laboratory diagnoses.

neuroscience↗