Seeking gene candidates responsible for developmental origins of health and disease.

Human epidemiological evidence has led scientists to theorize that undernutrition during gestation is an important early origin of adult diseases. Animal models have successfully demonstrated that maternal diet could contribute to some adult diseases. Undernutrition is perceived harmful in pregnant women, whereas calorie restriction is a strategy proven to extend healthy and maximum lifespan in adult. This diagrammatically opposite effect of nutritional condition might provide us with hints to search for genes underlying health conditions. Here, we have initiated a study examining the effect of undernutrition on maternal and fetal livers, utilizing high-throughput DNA microarray analysis for screening genome-wide changes in their transcriptomes. Briefly, pregnant mice were exposed to food deprivation (FD) on gestation day (GD) 17, and cesarean section was performed on GD18. Control mice were supplied with chow ad libitum until sacrifice. Total RNA extracted from mother and fetal livers for each control and treatment (FD) was analyzed with an Agilent mouse whole genome DNA chip. A total of 3058 and 3126 up- (>1.5-fold) and down- (<0.75-fold) regulated genes, and 1475 and 1225 up- (>1.5-fold) and down- (<0.75-fold) regulated genes showed differential expression at the mRNA level, in the maternal and fetal livers, respectively. Interestingly, 103 genes up-regulated in the mother were down-regulated in the fetus, whereas 108 down-regulated maternal genes were up-regulated in the fetus; these 211 genes are potential candidates related to longevity or health. The role of some of these genes, in context of the proposed mechanisms for developmental origins of health and disease is discussed.

Distribution of neuropeptide W in the rat brain.

Neuropeptide W (NPW), which was recently isolated from the porcine hypothalamus, has been identified as the endogenous ligand of the orphan G protein-coupled receptors GPR7 (NPBWR1) and GPR8 (NPBWR2). Infusion of NPW increases food intake in the light phase, whereas in the dark phase, it has the opposite effect. In this study, we used RT-PCR analysis to examine the gene expression of NPW mRNA in the rat brain, and performed a detailed analysis of the distribution of NPW-positive neurons by use of immunohistochemistry at both the light and electron microscopic levels. NPW mRNA expression was demonstrated in the hypothalamic paraventricular nucleus (PVN), arcuate nucleus (ARC), ventromedial nucleus (VMH) and lateral hypothalamus (LH). At the light microscopic level, NPW-like immunoreactive (NPW-LI) cell bodies were found in the preoptic area (POA), PVN, ARC, VMH, LH, PMD (dorsal premammillary nucleus), periaqueductal gray (PAG), lateral parabrachial nucleus (LPB), and prepositus nucleus (Pr). NPW-LI axon terminals were shown in the POA, bed nucleus of the stria terminalis (BST), amygdala, PVN, ARC, VMH, LH, and PAG, LPB. In addition, at the electron microscopic level, NPW-LI cell bodies and dendritic processes were often seen to receive inputs from other unknown neurons in the ARC, PVN, VMH and amygdala. Our observations indicate that NPW-LI neurons widely distributed in the rat brain region. These finding suggest that NPW may have important roles in feeding behavior, energy homeostasis, emotional response and regulation of saliva secretion.

Neural networks of several novel neuropeptides involved in feeding regulation.

Novel neuropeptides acting as G-protein-coupled receptor (GPCR) ligands are known to be localized in the brain and play a range of physiologic functions, one of which is feeding regulation. We describe the distribution and localization of these recently identified GPCR ligands and review their involvement in neuronal networks, particularly in feeding regulation. This review addresses aspects of some novel GPCR ligands, including feeding-regulating neuropeptides such as orexin, ghrelin, and galanin-like peptide and other known neuropeptides such as neuropeptide Y and pro-opiomelanocortin. These neuropeptides have been studied by our research group and others, particularly with regard to interactions in the hypothalamus of neurons containing these neuropeptides. In the hypothalamus, cross-talk among such neurons plays a key role in determining feeding states and feeding behavior. We describe some structural and functional characteristics of these neuropeptides and summarize the known interactions between the different kinds of feeding-regulating neurons and leptin-targeting neurons in the hypothalamus. Moreover, we present a new strategy for analyzing neural circuits involving these feeding-regulating GPCR ligands in the brain, with research in this field aided by the use of transgenic mouse models. We also present our recent results that involve aspects of feeding regulation, energy homeostasis, and body temperature regulation. Research in this field will serve the important role of clarifying neurologically based causes for appetite dysfunctions and diseases and may help in establishing new therapies for patients with such conditions.

Cytokine and nitric oxide production by Trypanosoma brucei infection in rats fed polyamine-deficient chow.

Feeding polyamine-deficient chow (PDC) to rats decreases blood polyamines, increases the activity of ornithine decarboxylase as an index of polyamine production, and increases resistance to Trypanosoma brucei gambiense (Wellcome strain) (WS) infection. In this study, we investigated the influence on cytokine and nitric oxide (NO) production of feeding PDC to rats infected with WS. At 4 days postinfection with WS, serum concentration of interleukin (IL)-12, tumor necrosis factor-alpha, interferon-gamma, IL-10, and NO increased in PDC-fed rats; however, IL-12 concentration in normal chow (NC)-fed rats did not increase. In spleen cells cocultured with WS, levels of IL-12 and inducible NO synthase (NOS) mRNA expression were higher in PDC-fed rats than in NC-fed rats. Proliferation of WS in coculture with spleen cells from PDC-fed rats was inhibited, but inhibition of WS proliferation was not observed when an NOS inhibitor was added into the culture media. Ornithine decarboxylase (ODC) activity increased in NC-fed rats after WS infection, but decreased in PDC-fed rats. These results show that feeding WS-infected rats PDC influences the production of cytokines such as IL-12 and the regulation of NO and polyamine production, and also leads to an increase in resistance against WS.

Synaptic relationships between proopiomelanocortin- and ghrelin-containing neurons in the rat arcuate nucleus.

Both proopiomelanocortin (POMC) and ghrelin peptides are implicated in the feeding regulation. The synaptic relationships between POMC- and ghrelin-containing neurons in the hypothalamic arcuate nucleus were studied using double-immunostaining methods at the light and electron microscope levels. Many POMC-like immunoreactive axon terminals were found to be apposed to ghrelin-like immunoreactive neurons and also to make synapses with ghrelin-like immunoreactive neuronal perikarya and dendritic processes. Most of the synapses were symmetrical in shape. A small number of synapses made by ghrelin-like immunoreactive axon terminals on POMC-like immunoreactive neurons were also identified. Both the POMC- and ghrelin-like immunoreactive neurons were found to contain large dense granular vesicles. These data suggest that the POMC-producing neurons are modulated via synaptic communication with ghrelin-containing neurons. Moreover, ghrelin-containing neurons may also have a feedback effect on POMC-containing neurons through direct synaptic contacts.