Dopaminergic Control of the Feeding Circuit

There is increasing evidence demonstrating that reward-related motivational food intake is closely connected with the brain’s homeostatic system of energy balance and that this interaction might be important in the integrative control of feeding behavior. Dopamine regulates motivational behavior, including feeding behaviors, and the dopamine reward system is recognized as the most prominent system that controls appetite and motivational and emotional drives for food. It appears that the dopamine system exerts a critical role in the control of feeding behavior not only by the reward-related circuit, but also by contributing to the homeostatic circuit of food intake, suggesting that dopamine plays an integrative role across the converging circuitry of control of food intake by linking energy state-associated signals to reward-related behaviors. This review will cover and discuss up-to-date findings on the dopaminergic control of food intake by both the reward-related circuit and the homeostatic hypothalamic system.

Dopaminergic Control of the Feeding Circuit

There is increasing evidence demonstrating that reward-related motivational food intake is closely connected with the brain’s homeostatic system of energy balance and that this interaction might be important in the integrative control of feeding behavior. Dopamine regulates motivational behavior, including feeding behaviors, and the dopamine reward system is recognized as the most prominent system that controls appetite and motivational and emotional drives for food. It appears that the dopamine system exerts a critical role in the control of feeding behavior not only by the reward-related circuit, but also by contributing to the homeostatic circuit of food intake, suggesting that dopamine plays an integrative role across the converging circuitry of control of food intake by linking energy state-associated signals to reward-related behaviors. This review will cover and discuss up-to-date findings on the dopaminergic control of food intake by both the reward-related circuit and the homeostatic hypothalamic system.

Melanocortin 4 Receptor and Dopamine D2 Receptor Expression in Brain Areas Involved in Food Intake

BACKGROUND: The melanocortin 4 receptor (MC4R) is involved in the regulation of homeostatic energy balance by the hypothalamus. Recent reports showed that MC4R can also control the motivation for food in association with a brain reward system, such as dopamine. We investigated the expression levels of MC4R and the dopamine D2 receptor (D2R), which is known to be related to food rewards, in both the hypothalamus and brain regions involved in food rewards. METHODS: We examined the expression levels of D2R and MC4R by dual immunofluorescence histochemistry in hypothalamic regions and in the bed nucleus of the stria terminalis (BNST), the central amygdala, and the ventral tegmental area of transgenic mice expressing enhanced green fluorescent protein under the control of the D2R gene. RESULTS: In the hypothalamic area, significant coexpression of MC4R and D2R was observed in the arcuate nucleus. We observed a significant coexpression of D2R and MC4R in the BNST, which has been suggested to be an important site for food reward. CONCLUSION: We suggest that MC4R and D2R function in the hypothalamus for control of energy homeostasis and that within the brain regions related with rewards, such as the BNST, the melanocortin system works synergistically with dopamine for the integration of food motivation in the control of feeding behaviors.

Cocaine-Induced Behavioral Sensitization in Mice: Effects of Microinjection of Dopamine D2 Receptor Antagonist into the Nucleus Accumbens

To determine the role of dopamine D2 receptor (D2R) in the nucleus accumbens (NAc) core in cocaine-induced behavioral sensitization, D2R antagonist, raclopride was bilaterally microinjected (2.5 or 5 nmol) into the NAc core of WT and D2R-/- mice and the initiation and expression phase of cocaine-mediated locomotor sensitization were analyzed. WT and D2R knockout (D2R-/-) mice received bilateral injections of either saline, or raclopride at the NAc core 30 min before each of five daily repeated injections of saline or cocaine (15 mg/kg i.p.). Following 2 weeks of withdrawal after repeated exposure to cocaine, the animals were pre-treated with an intra-accumbal injection of vehicle or raclopride before receiving a systemic cocaine challenge for the expression of sensitization. Animals which had been microinjected raclopride into NAc core displayed the enhancement of cocaine-induced behavioral response for the initiation but also for the expression of sensitization in WT as well as in D2R-/- mice, which was thus unaltered as compared to vehicle-injected control group. These results suggest that D2R in NAc core is not involved in cocaine-induced behavioral sensitization.

Agmatine Attenuates Nitric Oxide Synthesis and Protects ER-structure from Global Cerebral Ischemia in Rats / 대한해부학회지

In ischemic strokes, apoptosis is caused by excitotoxicity, ionic imbalance, oxidative/nitrosative stress, and apoptotic-like pathways. Nitric oxide (NO), a free radical, is elevated after ischemic insult. NO, which is generated primarily by neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS), promotes neuronal damage following ischemia. Evidence obtained in recent years has demonstrated that endoplasmic reticulum (ER)-mediated cell death plays an important role in cerebral ischemia. Agmatine is an endogenous substance synthesized from L-arginine by arginine decarboxylase (ADC) and is present in mammalian brain. We had previously reported that agmatine contributes to neuroprotection against ischemic injury. In continuation of our earlier work, we intended to investigate whether agmatine protects brain from transient global ischemia, and also tried to determine the neuroprotective mechanism of agmatine. Twenty minutes of transient global ischemia was induced by 4 vessel occlusion (4-VO). Agmatine (100 mg/kg, IP) was administered simultaneously with reperfusion. Samplings of brain were done at 6, 24, 48, and 72 h after reperfusion to determine the effect of agmatine on ischemic injured hippocampus. ER-damage was also investigated using electron microscope. Results showed that agmatine treatment prevented delayed neuronal cell death in hippocampal CA1 neurons after global cerebral ischemia. It also blocked NOS expression in the rat brain. Agmatine induced the increased expression of glucose-regulated protein 78 (Grp78). These results suggest that agmatine inhibits the production of NO by decreasing the expression of nNOS and iNOS on global forebrain ischemia and the neuroprotective effect of agmatine were concerned with the ER stress-mediated condition.

Rapid Prenatal Diagnosis of Trisomy 21 by Real-Time Quantitative Polymerase Chain Reaction / 대한산부인과학회잡지

OBJECTIVE: Trisomy 21 (Down syndrome) is the most common chromosomal anomaly which occurs 1 out of 700-1000 birth. Current techniques such as amniocentesis, chorionic villi sampling (CVS), require lengthy laboratory culture procedures and high costs. This study was undertaken to establish a rapid prenatal diagnosis of trisomy 21 using real-time quantitative polymerase chain reaction of fetal DNA from amniotic fluid. METHODS: Real-time quantitative PCR was performed with DNA template obtained from 14 normal serum, 10 normal amniotic fluid samples, 14 Down syndrome serum, and 7 Down syndrome amniotic fluid samples. Primers for D21S167 and S100B of chromosome 21 were used. Primers that direct amplification of 165-bp fragment of the IGFI (Insulin-like growth factor-1) gene on chromosome 12 are included to generate an internal standard for quantitation. RESULTS: The relative levels of D21S167 and S100B were 2.6 and 2.4 times higher in the serum of Down syndrome patients compared to the control group. The difference between these two groups was statistically significant (P-value: 0.0012 and 0.0016). The relative levels of D21S167 and S100B were 2.1 and 2.7 times higher in the amniotic fluid of Down syndrome fetuses compared to control group. The difference between these two groups was statistically significant (P-value 0.0379 respectively). CONCLUSION: Prenatal diagnosis of trisomy 21 by real-time quantitative PCR-associated STR (small tandem repeats) analysis of D21S167 and S100B is useful, accurate and rapid diagnostic method and also can be employed in diagnosis of trisomy 13, 18. Furthermore, it may also be useful for prenatal diagnosis with fetal DNA from maternal blood and for preimplantation genetic diagnosis.

Hypothaqlamic Control of Food Intake and Bodyweight: Role of Melanocortins / 대한내분비학회지

No abstract available.

The Expression and Distribution of MUC1 in Human Corneal Epithelium

Corneal and conjunctival squamous epithelial cells have been known to express the mucin MUC1. We attempted to reveal the expression and localizational characteristics of the membrane-spanning mucin MUC1 as a component of the mucous layer in the human corneal epithelium. An antibody to the MUC1 was used to detect the MUC1 on the corneal epithelium by immunohistochemistry and immunofluorescent staining. In situ hybridization was performed to determine the distribution of MUC1 mRNA in the ocular surface. Immunohistochemically, the MUC1 mucin was observed along the apical membranes of the corneal epithelium. According to immunofluorescent staining, cells varied in the amount of mucin MUC1. Expression of MUC1 mRNA was observed in all layers of the corneal epithelium. The MUC1 mucin synthesized by the corneal epithelia exists on the apical membrane of the superficial cells. The amount of MUC1 may vary with the vertical migration and the activity of the cells.

Action Mechanisms of Hormone Binding to Cell Surface Receptors: 1) G-protein Coupled Receptor Signalling as Targets for Hormone Action: (1) Adenylate Cyclase Cascade / 대한내분비학회지

No Abstract Available.

G Protein Coupled Receptor Signaling: Recent Progress / 대한내분비학회지

No abstract available.