Refeeding activates neurons in the dorsomedial hypothalamus to inhibit food intake and promote positive valence.

OBJECTIVE: The regulation of food intake is a major research area in the study of obesity, which plays a key role in the development of metabolic syndrome. Gene targeting studies have clarified the roles of hypothalamic neurons in feeding behavior, but the deletion of a gene has a long-term effect on neurophysiology. Our understanding of short-term changes such as appetite under physiological conditions is therefore still limited. METHODS: Targeted recombination in active populations (TRAP) is a newly developed method for labeling active neurons by using tamoxifen-inducible Cre recombination controlled by the promoter of activity-regulated cytoskeleton-associated protein (Arc/Arg3.1), a member of immediate early genes. Transgenic mice for TRAP were fasted overnight, re-fed with normal diet, and injected with 4-hydroxytamoxifen 1 h after the refeeding to label the active neurons. The role of labeled neurons was examined by expressing excitatory or inhibitory designer receptors exclusively activated by designer drugs (DREADDs). The labeled neurons were extracted and RNA sequencing was performed to identify genes that are specifically expressed in these neurons. RESULTS: Fasting-refeeding activated and labeled neurons in the compact part of the dorsomedial hypothalamus (DMH) that project to the paraventricular hypothalamic nucleus. Chemogenetic activation of the labeled DMH neurons decreased food intake and developed place preference, an indicator of positive valence. Chemogenetic activation or inhibition of these neurons had no influence on the whole-body glucose metabolism. The labeled DMH neurons expressed prodynorphin (pdyn), gastrin-releasing peptide (GRP), cholecystokinin (CCK), and thyrotropin-releasing hormone receptor (Trhr) genes. CONCLUSIONS: We identified a novel cell type of DMH neurons that can inhibit food intake and promote feeding-induced positive valence. Our study provides insight into the role of DMH and its molecular mechanism in the regulation of appetite and emotion.

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 induces changes in hypothalamic distribution and amounts of phospholipids, especially arachidonic-acid-containing phospholipids, that are 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), lowers insulin sensitivity in muscles during regular chow diet (RCD) feeding. Conversely, the down-regulation of glucose metabolism by high fat diet (HFD) feeding is 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.

8-Substituted 2-alkynyl-N(9)-propargyladenines as A2A adenosine receptor antagonists.

Structure-activity relationships of 2-alkynyladenine derivatives were explored by varying substituents at the 9-, 8- and 2-positions of the purine moiety in order to optimize A2A adenosine receptor antagonist activity in vitro. A propargyl group at the 9-position was found to be important for A2A antagonist activity, and the introduction of a halogen, aryl, or heteroaryl at the 8-position further enhanced activity. A series of 8-substituted 2-alkynyl-N(9)-propargyladenine derivatives exhibited potent antagonist activity, with IC50 values in the low nM range. Compound 4a from this series was found to be orally active at a dose of 3 mg/kg in a mouse catalepsy model and a 6-hydroxydopamine-lesioned rat model of Parkinson's disease.

The influence of water on the stability of lyophilized formulations with inositol and mannitol as excipients.

The stability of a moisture-sensitive drug in lyophilized products was investigated under conditions with varying water content and temperature using two model formulations: a formulation containing inositol (IF) as the excipient and a formulation containing mannitol (MF) as the excipient. IF showed better chemical stability (a lower hydrolysis rate) than MF when both formulations contained 2% water. However, in the case of formulations with 8% water, MF showed similar or better stability than IF. From the results of hygroscopicity and phase transition experiments for both formulations, it was assumed that this stability profile was exhibited because 1) more water was taken up into the amorphous inositol in IF than into the crystalline Form-III mannitol in MF at a low water content, so that drug hydrolysis in IF was suppressed compared with MF and 2) when the water content increased, the amorphous inositol crystallized to anhydrate in IF causing expulsion of absorbed water from the excipient, meaning that IF lost its superior chemical stability due to the highly mobile water generated by the crystallization. This assumption was supported by the results of the (2)H-NMR measurement, which estimated water mobility from the signal shape and the spin-lattice relaxation time (T(1)) of deuterium oxide.

Investigation of intermolecular interaction in molecular complex of tryptamine and benzoic acid by solid-state 2D NMR.

Solid-state NMR spectra and powder X-ray diffraction of the two-component molecular complex composed of tryptamine and benzoic acid were observed to investigate the intermolecular interaction in the molecular complex. 1D (13)C CP/MAS NMR spectrum and powder X-ray diffraction pattern of the complex was clearly different from the convolution of each spectrum of the single component. 2D (1)H-(13)C heteronuclear-correlation (HETCOR) NMR technique indicated that the intermolecular interaction between the primary amine of tryptamine and the carboxyl group of benzoic acid must be related to the complex formation.