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At least 217 records · Page 12Linked to original sources
PubMed1977

Saccharin aversion in the rat following adrenalectomy.

Changes in saccharin preference as a function of concentration were studied in rats after either adrenalectomy of sham surgery. A 48 hr two-bottle preference test was used. Under two different sets of testing conditions, adrenalectomized animals rejected saccharin solutions at concentrations that were highly acceptible to controls and did not show an appetitive behavior towards andy of the concentrations tested. This aversion pattern persisted even when preference tests were conducted for as long as 10 days. However, it was abolished when the adrenalectomized rats wre exposed to saccharin for 6 days prior to surgery, or when they were administered the glucocorticoid dexamethasone. Results are discussed with respect to the effects of adrenal hormones on sensory systems and to taste-aversion learning.

Adrenalectomy↗
PubMed1979

Suppression of deprivation-induced food and water intake in rats and mice by naloxone.

Naloxone, an opiate antagonist, was administered to male and female rats and male mice after periods of food or water deprivation ranging from 12 to 48 hr. Naloxone (0.01-10 mg/kg) reduced postdeprivational water intake in most groups of rats and mice in a dose-related manner. Naloxone suppression of water consumption appeared to be independent of sexual differences in rats, and phase of the diurnal cycle, and length of the deprivation interval in both rats and mice. Postdeprivational food intake in male rats and mice was also reduced by naloxone in a dose-dependent fashion. This naloxone effect was less pronounced than actions observed with water intake, and tended to diminish with lengthening food deprivation periods. In general, mice appeared to be less sensitive than rats to naloxone suppression of food and water intake. Naloxone appears to markedly reduce appetitive behavior, particularly water intake, following deprivation in both rats and mice. The fact that low doses of naloxone can elicit these effects suggests that the drug is acting at specific tissue sites, possibly endorphine recpetors.

Animals↗
PubMed1979

Suppressant effects of naltrexone on water intake in rats.

Parenteral administration of naltrexone to water-deprived female rats suppressed water intake when injected 4, but not 12 hours prior to the drinking session. Intraperitoneal injection 5 mg/kg naltrexone twice daily or oral self-administration of naltrexone in doses sufficient to block morphine-induced analgesia failed to reduce water intake or to alter body weight in non-deprived animals. These findings suggest that the suppressant effects of naltrexone on appetitive behavior are mediated by a different population of opiate receptors than those mediating morphine-induced analgesia.

Animals↗
PubMed1996

Naloxone decreases intake of 10% sucrose in preweanling rats.

To investigate the role of opioids in the mediation of sucrose intake in the preweanling rat pup, we measured the effect of naloxone on intake of pups licking 10% sucrose from the floor of a beaker (independent ingestion test) and of pups ingesting 10% sucrose that was continuously infused through an anterior, sublingual oral catheter (oral catheter test). Pups were tested only once to eliminate the possible effect of test experience. Pups were tested in the second postnatal week (PN7, 9, 10, 11, and 14 days) with naloxone (1 mg/kg) or vehicle controls. Fourteen-day-old pups were also tested with 0.1 and 0.5 mg/kg. Naloxone began to be efficacious for inhibiting intake on PN10 in the oral catheter test and on PN11 in the independent ingestion test. On PN14, the inhibition of intake was dose related and naloxone was more potent for inhibiting intake in independent ingestion tests than in oral catheter tests. Naloxone not only decreased intake, it also decreased the incidence of licking, increased mouthing and resting, and had no significant effect on locomotion. The site of the inhibitory effect of naloxone on intake was in the central nervous system, presumably in the brain, because naloxonemethiodide, an analogue of naloxone that does not cross the blood-brain barrier, did not inhibit sucrose in either test. These results demonstrate that the intake of 10% sucrose depends on endogenous opioids as early as PN10 and that this opioid mechanism operates when pups have not had prior test experience and in a test (oral catheter test) where intake is not dependent on appetitive behaviors.

Animals↗
PubMed1994

The gut-brain peptide cyclo(His-Pro) is secreted in a pulsatile fashion in fasting humans.

Histidyl-proline diketopiperazine (CHP) is a cyclic dipeptide that is found in many animal tissues, most notably brain and gut. It has been found to have a variety of biologic actions and has been postulated to play a role in appetitive behavior and energy metabolism. This study was conducted in order to characterize the secretory pattern of CHP during a 24 h fast. Four subjects (2 obese and 2 lean) were studied during the latter 24 h of a 36 h fast. Blood was sampled every 10-15 min and assayed for CHP concentration using a specific radioimmunoassay. Analysis revealed that circulating CHP oscillates in humans and that diurnal variation occurred but only in the obese subjects.

Adult↗
PubMed1988

Precursor amino acid concentrations in normal weight bulimics and normal controls.

1. CNS serotonergic neurotransmission has been implicated in the control of appetitive behavior. The ratio of plasma tryptophan (TRP) to other large neutral amino acids (LNAA) is believed to regulate CNS serotonin (5-HT) synthesis. 2. After an overnight fast, plasma TRP ratios were determined in 23 normal weight bulimics and 7 normal controls. 3. All subjects were assessed for mood disorder using a SADS interview and Beck Depression ratings. 4. There was no significant difference in TRP ratios between bulimics and normal controls. TRP ratios in depressed bulimics were not significantly different from those of nondepressed bulimics. 5. Potential abnormalities in CNS serotonergic function in bulimics are not reflected in decreased baseline TRP ratios. Further investigation of the dynamic serotonergic system may prove fruitful. 6. Reduced availability of tryptophan for conversion to serotonin is not likely to be the postulated biological abnormality common to both depression and bulimia.

Adult↗
PubMed1995

Current concepts of imaging in patients with pituitary/hypothalamic dysfunction.

MRI has value in differentiating the normal anatomy and abnormalities of the hypothalamic and pituitary regions. The hypothalamus and the pituitary gland are contiguous structures. They are functionally and physiologically inseparable. The hypothalamus functions primarily as an integrating mechanism for various autonomic and neuroendocrine activities, including temperature regulation, water balance, behavior, and appetite. The adenohypophysis of the pituitary gland contains at least five histologically distinct cell types responsible for hormonal secretion. The characteristic locations of these functional cell types correlate well with the common sites of various pituitary adenomas. MRI can visualize the pituitary gland and the hypothalamus noninvasively in healthy people and in patients with diverse diseases.

Adenoma↗
PubMedDate not supplied

Accumbal dopamine concentration during operant self-administration of a sucrose or a novel sucrose with ethanol solution.

The goal of the current study was to determine the effect of operant self-administration of (1) 10% sucrose and (2) a first-time solution of 10% sucrose with 5% or 10% ethanol, on dopamine concentration in the nucleus accumbens. We used an operant procedure that distinguished lever pressing (an appetitive behavior) from drinking to better assess the effect of fluid consumption on accumbal dopamine activity. Male Long-Evans rats were trained to bar press by using 10% sucrose reinforcement, and they were required to emit an escalating number of bar presses across daily sessions. Completion of the response requirement resulted in 20 min of access to the solution. Microdialysis samples were collected before, during, and after bar pressing and drinking, and content of ethanol and dopamine was determined. Dopamine concentration in the dialysate was slightly, but significantly, increased in both groups during lever pressing. However, after consumption began, dopamine concentration increased in the sucrose, but not in the sucrose with ethanol, group, followed by a return to baseline values. Ethanol consumption was low (0.27 +/- 0.02 g/kg) and corresponded to low dialysate ethanol concentrations, which appeared within 5 min of drinking. These results demonstrate that operant self-administration of sucrose increases accumbal dopamine concentration during consummatory phases of behavior, but that a similar increase is not apparent when a novel, perhaps aversive, solution (sucrose with ethanol) is presented. This difference may be due to the sensory-related stimulus properties of each solution. In addition, oral self-administration of ethanol at 0.27 +/- 0.02 g/kg over 20 min is not sufficient for stimulation of dopamine activity in the nucleus accumbens.

Animals↗
PubMed2005

Evolution of the DRD2 gene haplotype and its association with alcoholism in Mexican Americans.

The human D2 dopamine receptor gene (DRD2) plays a central role in the neuromodulation of appetitive behaviors and is implicated in having a possible role in susceptibility to alcoholism. We genotyped an SNP in DRD2 Exon 8 in 251 nonalcoholic, unrelated, healthy controls and 200 alcoholic Mexican Americans. The DRD2 haplotypes were analyzed using the Exon 8 genotype in combination with five other SNP genotypes, which were obtained from our previous study. The ancestral origins of the DRD2 polymorphisms have been determined by sequencing the homologous region in other higher primates. Twenty DRD2 haplotypes, defined as H1 to H20 based on their frequency from high to low, were obtained in this major minority population. The ancestral haplotype "I-B2-G-C-G-A1" and two one-step mutation haplotypes were absent in our study population. The haplotype H1, "I-B1-T-C-A-A1", with the highest frequency in the population, is a three-step mutation from the ancestral form. The first five or eight major haplotypes make up 87% or 95% of the entire population, respectively. The prevalence of the haplotype H1+ (H1/H1 and H1/Hn genotypes) is significantly higher in alcoholics and alcoholic subgroups, including early onset drinkers and benders, than in their respective control groups. The Promoter -141C allele is in linkage disequilibrium (LD) with five other loci in the nonalcoholic group, but not in the alcoholic group. All of the other five loci are in LD in both the alcoholic and control groups. The DRD2 TaqI B allele is in complete LD with the allele located in intron 6. Five SNPs, Promoter -141C, TaqI B (or Intron 6), Exon 7, Exon 8, and TaqI A, are sufficient to define the DRD2 haplotypes in Mexican Americans. Our data indicate that the DRD2 haplotypes are associated with alcoholism in Mexican Americans.

Adult↗
PubMed2003

Brain-derived neurotrophic factor in the ventral midbrain-nucleus accumbens pathway: a role in depression.

BACKGROUND: Previous work has shown that brain-derived neurotrophic factor (BDNF) and its receptor, tyrosine kinase receptor B (TrkB), are involved in appetitive behavior. Here we show that BDNF in the ventral tegmental area-nucleus accumbens (VTA-NAc) pathway is also involved in the development of a depression-like phenotype. METHODS: Brain-derived neurotrophic factor signaling in the VTA-NAc pathway was altered in two complementary ways. One group of rats received intra-VTA infusion of vehicle or BDNF for 1 week. A second group of rats received intra-NAc injections of vehicle or adeno-associated viral vectors encoding full-length (TrkB.FL) or truncated (TrkB.T1) TrkB; the latter is kinase deficient and serves as a dominant-negative receptor. Rats were examined in the forced swim test and other behavioral tests. RESULTS: Intra-VTA infusions of BDNF resulted in 57% shorter latency to immobility relative to control animals, a depression-like effect. Intra-NAc injections of TrkB.T1 resulted in and almost fivefold longer latency to immobility relative to TrkB.FL and control animals, an antidepressant-like effect. No effect on anxiety-like behaviors or locomotion was seen. CONCLUSIONS: These data suggest that BDNF action in the VTA-NAc pathway might be related to development of a depression-like phenotype. This interpretation is intriguing in that it suggests a role for BDNF in the VTA-NAc that is opposite of the proposed role for BDNF in the hippocampus.

Animals↗
PubMed2003

Neuroendocrinology of the pancreas; role of brain-gut axis in pancreatic secretion.

Exocrine pancreatic secretion, attributed initially to neural reflexes (nervism), was then found to depend also on enterohormones, especially secretin and cholecystokinin (CCK), released by the intestinal mucosa and believed to act via an endocrine pathway. Recently, CCK and other enterohormones were found to stimulate the pancreas by excitation of sensory nerves and by trigger of long vagovagal or ("brain-gut axis") enteropancreatic reflexes. Numerous neurotransmitters, such as acetylcholine, and certain neuropeptides, such as gastrin-releasing peptide (GRP), generated by neurons of the enteric nervous system (ENS) of the gut, have been implicated in the regulation of exocrine pancreas. Recently, peptides affecting appetite behavior and originating from the gut, such as leptin and ghrelin, or from the pancreas, such as pancreatic polypeptide and neuropeptide Y, appear to modulate the exocrine pancreas via hypothalamic centers. The aim of this review is to highlight the interaction of nerves and enterohormones in the regulation of exocrine pancreatic secretion.

Animals↗
PubMed2004

Dissociable effects of arousal and valence on prefrontal activity indexing emotional evaluation and subsequent memory: an event-related fMRI study.

Prefrontal cortex (PFC) activity associated with emotional evaluation and subsequent memory was investigated with event-related functional MRI (fMRI). Participants were scanned while rating the pleasantness of emotionally positive, negative, and neutral pictures, and memory for the pictures was tested after scanning. Emotional evaluation was measured by comparing activity during the picture rating task relative to baseline, and successful encoding was measured by comparing activity for subsequently remembered versus forgotten pictures (Dm effect). The effect of arousal on these measures was indicated by greater activity for both positive and negative pictures than for neutral ones, and the effect of valence was indicated by differences in activity between positive and negative pictures. The study yielded three main results. First, consistent with the valence hypothesis, specific regions in left dorsolateral PFC were more activated for positive than for negative picture evaluation, whereas regions in right ventrolateral PFC showed the converse pattern. Second, dorsomedial PFC activity was sensitive to emotional arousal, whereas ventromedial PFC activity was sensitive to positive valence, consistent with evidence linking these regions, respectively, to emotional processing and self-awareness or appetitive behavior. Finally, successful encoding (Dm) activity in left ventrolateral and dorsolateral PFC was greater for arousing than for neutral pictures. This finding suggests that the enhancing effect of emotion on memory formation is partly due to an augmentation of PFC-mediated strategic, semantic, and working memory operations. These results underscore the critical role of PFC in emotional evaluation and memory, and disentangle the effects of arousal and valence across PFC regions associated with different cognitive functions.

Adult↗
PubMed2005

Phosphoproteomic analysis of the effect of cyclo-[His-Pro] dipeptide on PC12 cells.

The effects of dipeptide cyclo-[His-Pro] (CHP), known to participate in the appetite behavior and food intake control, have been investigated using PC12 cells in culture as model system. We found that only in the presence of experimental conditions that cause cellular stress the cyclic dipeptide affect cellular proliferation and protects from apoptosis. It greatly enhances the phosphorylation of hsp27, alpha-B-crystallin, Cdc2, and p-38 MAPK, whereas it decreases the phosphorylation of MEK1, Cav 2, GSK3a, PKB/Akt, PKCdelta, PKCgamma, and Erk2. PKA and PKG are involved in ERK1/2 deactivation via a receptor that appears to be dually coupled to Gs and Gq protein subfamilies.

Animals↗
PubMed2006

Effect of delta9-tetrahydrocannabinol on quinine palatability and AM251 on sucrose and quinine palatability using the taste reactivity test.

Here we provide evidence that the cannabinoid agonist, Delta9-tetrahydrocannabinol (Delta9-THC) enhances quinine palatability and the CB1 antagonist/inverse agonist, AM251, reduces sucrose and quinine palatability using the taste reactivity test, which provides a direct measure of palatability independently of appetitive behavior. In Experiment 1, rats were treated with a low dose of Delta9-THC (0.5 mg/kg) or Vehicle 30 min, 60 min, 120 min or 240 min prior to a 5-min intraoral infusion of a highly unpalatable 0.05% quinine solution. Regardless of the post-injection interval, Delta9-THC reduced rejection of quinine. The Delta9-THC-induced palatability shift was reversed by AM251. In Experiment 2, rats were injected with either AM251 (1 mg/kg) or Vehicle prior to receiving a 5-min intraoral infusion of either 32% sucrose or 0.05% quinine solution. AM251 significantly decreased sucrose-elicited hedonic reactions across both time intervals; however, AM251 did not significantly modify the rejection of 0.05% quinine solution. When the concentration of the quinine solution was reduced to 0.01% in Experiment 3, AM251 enhanced quinine aversion. Although the range of concentrations of the solutions tested in the present data is limited, our results suggest that the cannabinoid system may modulate the palatability of ingested substances regardless of the palatability of the ingested substance.

Animals↗
PubMed2006

Neural correlates of habituation to taste stimuli in healthy women.

Recent studies show that specific regions of the cortex contribute to modulation of appetitive behaviors. The purpose of this study was to determine whether neural response in these regions changes over time when a taste stimulus is administered repeatedly. Such a paradigm may be useful for determining whether altered habituation contributes to disturbed eating behavior. This study used a programmable syringe pump to compare administration of a 10% sucrose solution to distilled water in 11 healthy female subjects using functional magnetic resonance imaging. The stimuli were presented in either a sequential or pseudorandom order. An a priori 'Region of Interest' (ROI) based analysis method was used, with ROIs defined in the prefrontal cortex, insula, amygdala, and hippocampus. To test habituation, activation during the first half of each block was compared with activation during the second half. For the pseudorandom blocks, subjects showed habituation in almost all ROIs to water, but in none to sucrose. By contrast, for sequential blocks, both stimuli produced habituation in taste-related brain regions. These data suggest that habituation patterns in healthy subjects may depend on frequency and regularity of stimulus administration.

Adult↗
PubMed2002

Anorexigenic melanocortin signaling in the hypothalamus is augmented in association with failure-to-thrive in a transgenic mouse model for Prader-Willi syndrome.

As in Prader-Willi syndrome (PWS) infants, mouse models of PWS display failure-to-thrive during the neonatal period. In rodents, the hypothalamic neuropeptide, Neuropeptide Y (NPY) and Agouti-related peptide (AgrP) stimulate while alpha-melanocyte stimulating hormone (alpha-MSH) inhibits appetite. We hypothesized that altered expression of these neuropeptides in the hypothalamus may underlie the failure-to-thrive in PWS neonatal mice. To test this hypothesis we evaluated mRNA expression of Npy, Agrp, and Pomc by in situ hybridization in the hypothalamic arcuate nucleus (ARC) of 3-day-old female and male PWS neonates. The results showed that Agrp mRNA expression was decreased relative to wild-type (WT) controls in neonates of both sexes, while mRNA expression of Pomc was upregulated in PWS neonates. Since AgrP and the Pomc-derived peptide, alpha-MSH, are functional antagonists at melanocortin 4 receptors in the hypothalamic regulation of appetitive behavior, these results show that robust anorexigenic melanocortin signaling, may contribute to the failure-to-thrive in PWS neonatal mice.

Agouti-Related Protein↗
PubMed2003

Effects of thyroid hormone on food intake, hypothalamic Na/K ATPase activity and ATP content.

The effects of thyroid hormone on whole body energy metabolism and compensatory effects on food intake are well established. However, the hypothalamic mechanisms that translate perceived whole body energy demands into subsequent appetitive behavior are incompletely understood. In order to address this question, we tested the effects of T3 on food intake and body weight in rats and measured neuronal Na/K ATPase activity and ATP content in the hypothalamus. Intraperitoneal T3 (100 microg/kg BW) administered for 6 consecutive days increased 24-h rat food intake from control, 26.6+/-1.2, to T3-treated 33.2+/-1.6 g (P<0.01). In T3-treated rats, rubidium-86 (86Rb) uptake (measured as a marker of Na/K ATPase activity) in ex vivo hypothalamic tissue increased (P<0.01) while the content of ATP in the ventral hypothalamus declined following T3 treatment (P<0.01). In another model of energy deficit, which was induced by a very low calorie diet, ATP content was also reduced in the hypothalamus compared to rats fed ad libitum. In summary, increased food intake in response to T3 may be secondary to decreased hypothalamic ATP content, perhaps resulting from both increased Na/K ATPase activity in the hypothalamus and metabolic signaling induced by whole body caloric deficit.

Adenosine Triphosphate↗
PubMed1998

Enterostatin (Val-Pro-Asp-Pro-Arg)-like immunoreactivity in rat urine: relationship to corticosterone output.

Numerous studies have documented a role for enterostatins in appetitive behavior. However, due to the lack of knowledge about the distribution of enterostatins in tissues and body fluids, it has not been possible to examine the role of endogenous enterostatin in this process. To this end, using a polyclonal antibody raised against enterostatin -- Val-Pro-Asp-Pro-Arg (VPDPR), we examined the nature and distribution of enterostatin-like immunoreactivity in the rat urine by ELISA and chromatography. The results reported here show for the first time the presence of VPDPR-like immunoreactivity (VPDPR-LI) in rat urine. Further characterization of rat urine VPDPR-LI revealed that it is not due to VPDPR but to another peptide similar to VPDPR. Furthermore, as urinary excretion of corticosterone increases, the level of VPDPR-LI in urine decreases.

Amino Acid Sequence↗