Decreased behavioral effects of daily intracerebroventricular bombesin

Transcriptomic analysis of Rongchang pig brains and livers

Recent developments in high-throughput RNA sequencing (RNA-seq) technology have led to a dramatic impact on our understanding of the structure and expression profiles of the mammalian transcriptome. To gain insights into the usefulness of swine production and biomedical model, the transcriptome profiling of Rongchang pig brains and livers was characterized using RNA-seq technology to uncover functional candidate molecules. In the study, total RNAs from brains and livers of Rongchang pig were sequenced and 8.6Gb sequencing data was obtained. This analysis revealed tissue specificity through the identification of 5575 and 4600 differentially expressed genes (DEGs) in brains and livers, respectively and the functional analysis of DEGs. Furthermore, 83 neuropeptide gene transcripts, 69 neuropeptide receptor gene transcripts, 10 pro-neuropeptide convertase gene transcripts and many other neuropeptide related protein gene transcripts were identified. Totally, the major characteristics of the transcriptional profiles of Rongchang pig brains and livers were present.

Neuropeptides, food intake and body weight regulation: a hypothalamic focus

Energy homeostasis is controlled by a complex neuroendocrine system consisting of peripheral signals like leptin and central signals, in particular, neuropeptides. Several neuropeptides with anorexigenic (POMC, CART, and CRH) as well as orexigenic (NPY, AgRP, and MCH) actions are involved in this complex (partly redundant) controlling system. Starvation as well as overfeeding lead to changes in expression levels of these neuropeptides, which act downstream of leptin, resulting in a physiological response. In this review the role of several anorexigenic and orexigenic (hypothalamic) neuropeptides on food intake and body weight regulation is summarized.

Effects of peptides on animal and human behavior: a review of studies published in the first twenty years of the journal Peptides

This review catalogs effects of peptides on various aspects of animal and human behavior as published in the journal Peptides in its first twenty years. Topics covered include: activity levels, addiction behavior, ingestive behaviors, learning and memory-based behaviors, nociceptive behaviors, social and sexual behavior, and stereotyped and other behaviors. There are separate tables for these behaviors and a short introduction for each section.

Bombesin microinjection into the basolateral amygdala influences feeding behavior in the rat

It has been demonstrated that the basolateral amygdala (ABL) represents a satiety mechanism. Experimental data indicate that peripheral or central applications of neuropeptide bombesin (BN) and BN-like peptides inhibit feeding. Since the amygdala (AMY) is rich in BN-like immunoreactive elements, the present study was performed to determine whether 10 or 40 ng doses of BN microinjected bilaterally into the ABL could modify solid food intake. Twenty nanograms of BN (10 ng per injection site) in 24-h deprived rats caused transient inhibition of food intake and 80 ng resulted in a significant reduction of food consumption for 1 h. This inhibitory effect of BN on feeding was eliminated by prior BN antagonist treatment. Results of behavioral tests showed that BN microinjections into the ABL specifically reduced food intake without altering behavioral patterns or influencing the body temperature. Present results suggest that BN-like peptides may act as a complex satiety signal in the ABL.

Bombesin injection into the central amygdala influences feeding behavior in the rat

The present study was performed to determine whether low doses (10 or 40 ng) of bombesin microinjected into the amygdala could modify solid food intake. Forty ng of bombesin in 24 h deprived rats caused transient inhibition of food intake. This inhibitory effect was eliminated by prior bombesin antagonist treatment. A series of quantitative behavioral tests indicated that low doses of bombesin application specifically reduced food intake without altering the behavioral pattern or influencing the body temperature. The present results suggest, that bombesin-like peptides may act as a satiety signal in the central part of the amygdala.

Sustained bombesin exposure results in receptor down-regulation and tolerance to the chronic but not acute effects of bombesin on ingestion

Acute intracerebroventricular (i.c.v.) administration of bombesin (BN) reduces meal intake in fasted rats. The overall objective of the present study was to determine the behavioral and other ingestive effects of prolonged central administration of BN. In the first experiment, we characterized the effects of 8-day sustained central administration of BN (0, 0.01, 0.05, 0.1 and 5 micrograms/0.5 microliter/h) or its antagonist (BIM-26226; 0, 0.005, 0.05, 0.5 and 5.0 micrograms/0.5 microliter/h), in free feeding rats. Each dose was delivered over 48 h, in an ascending sequence. At the higher doses, the BN-exposed rats consumed significantly less food whereas those exposed to the BN antagonist ingested significantly more food than the controls (saline exposed), during the dark phase. Due to the limited 48-h exposure to these higher doses, we further investigated the effects of more sustained BN exposure. Thus BN was infused over a 7-day period, at a rate of 0.25 microgram BN/0.5 microliter/h. In this latter study, we determined the effects of sustained BN exposure on a) daily spontaneous ingestive pattern, b) the rat's ingestive and other behavioral responses to a subsequent acute BN (i.c.v.) challenge and, c) BN receptor binding profile in various brain regions. Over the initial 2 days of chronic infusion, BN significantly suppressed spontaneous ingestion, and this effect dissipated by 72 h. Upon acute challenge with bolus injection of BN (0.25 microgram; i.c.v.), both chronically BN-treated and control rats responded by decreased feeding and enhanced grooming behaviors. In terms of effects at the receptor level, chronic BN exposure resulted in significant down-regulation (reduced BN/GRP receptor density) at the PVN and the hippocampal dentate gyrus. These findings represent the first demonstration of concomitant behavioral and receptor based changes consequent to sustained exposure to BN. These data suggest that tolerance to feeding suppressant effects of BN develops gradually, which in part may be mediated by down-regulation of BN/GRP receptors at specific brain loci. Our results also suggest that despite the development of tolerance to the chronic or sustained effects of BN exposure, animals still respond robustly to acute fluctuations in peptide levels.

Meal pattern analysis in rats reveals partial agonist activity of the bombesin receptor antagonist BW2258U89

The spontaneous feeding behavior of adult male rats was monitored during continuous infusion of the bombesin receptor antagonist BW2258U89 into the coeliac artery (100 micrograms kg-1 h-1) from an osmotic minipump. Nocturnal food intake was suppressed over 5 days of testing. Similar effects followed acute BW2258U89 treatment [100 micrograms kg-1, intraperitoneally (i.p.)]. Moreover, i.p. BW2258U89 mimicked the acute behavioral effects of 2 micrograms kg-1 i.p. bombesin by reducing meal size. Verifying that BW2258U89 can retain its potency throughout the entire period of chronic infusion, we demonstrated that the acute anorectic action of bombesin (4 micrograms kg-1, i.p.) was blocked by pretreatment with a BW2258U89 solution (100 micrograms ml-1 kg-1, i.p.) that was freshly prepared, or incubated for 1 or 6 days at body temperature. These data demonstrate that acute and chronic administration of BW2258U89, at a dose that abolishes the satiety effect of bombesin, significantly suppresses spontaneous feeding. Thus, BW2258U89 appears to attenuate food intake by acting as a partial agonist at peripheral receptors for bombesin-like peptides.

CNS effects of peptides: a cross-listing of peptides and their central actions published in the journal Peptides, 1986-1993

The centrally mediated effects of peptides as published in the journal Peptides from 1986 to 1993 are tabulated in two ways. In one table, the peptides are listed alphabetically. In another table, the effects are arranged alphabetically. Most of the effects observed after administration of peptides are grouped, wherever possible, into categories such as cardiovascular and gastrointestinal. The species used in most cases has been rats; where other animals were used, the species is noted. The route of administration of peptides and source of information also are included in the tables, with a complete listing provided at the end. Many peptides have been shown to exert a large number of centrally mediated effects.

Galanin antagonists block galanin-induced feeding in the hypothalamus and amygdala of the rat

Galanin significantly increased food intake when microinjected into the region of the central nucleus of the amygdala as well as into the paraventricular nucleus of the hypothalamus. In the amygdala this effect was specific to feeding; no change in grooming, resting, or other behaviour was observed after galanin treatment. These results provide evidence that the amygdala may be an important site in the mediation of galanin-induced feeding. The galanin receptor antagonists, C7 and M40, antagonized galanin-induced feeding, while having no effect alone on food consumption in free-feeding rats. These new galanin receptor antagonists provide useful tools for further investigating the role of endogenous galanin in the regulation of feeding.