Food consistency modulates eating volume and speed through brain histamine in rat

Masticatory dysfunction in patients with diabetic neuropathy: A cross-sectional study

Introduction

Chewing well is essential for successful diet therapy and control of blood glucose level in patients with diabetes. In addition, long-term hyperglycemia is a risk factor for microvascular complications, which are the main cause of morbidity and mortality in these patients. Hence, it is plausible that masticatory disorder may be relevant to diabetic microvascular complications which is caused by long-term hyperglycemia. The aim of this study was to investigate whether masticatory disorders are relevant to diabetic microvascular complications.

Methods

This cross-sectional study included 172 patients with type 2 diabetes who underwent educational hospitalization in the Department of Endocrinology and Diabetic Medicine, Hiroshima University Hospital, from April 2016 to March 2020. Masticatory efficiency was determined quantitatively by using the GLUCO SENSOR GS-Ⅱ. Multivariable linear regression models were constructed to examine which factors were related to masticatory efficiency. Statistical significance was defined as a two-sided p value of < 0.05.

Results

According to the bivariable analysis, masticatory efficiency was significantly correlated with duration of diabetes (p = 0. 049), number of remaining teeth (p < 0.0001), the number of moving teeth (p = 0.007) and condition of diabetic neuropathy (p < 0.0001). Moreover, the number of remaining teeth (p < 0.0001) and diabetic neuropathy (p = 0.007) remained significantly correlated with masticatory efficiency in the multivariable analysis.

Conclusions

For the first time, we demonstrated that patients with type 2 diabetes who developed diabetic neuropathy had significantly reduced masticatory efficiency. Effective mastication is an important factor in successful diet therapy for diabetes. To prevent the progression of diabetic complications, especially in patients with diabetic neuropathy, it may be necessary to combine individualized therapies from dentists and nutritionists with consideration for the level of masticatory dysfunction.

Chewing increases postprandial diet-induced thermogenesis

Slow eating, which involves chewing food slowly and thoroughly, is an effective strategy for controlling appetite in order to avoid being overweight or obese. Slow eating also has the effect of increasing postprandial energy expenditure (diet-induced thermogenesis). It is still unclear whether this is due to oral stimuli; that is, the duration of tasting food in the mouth and the duration of chewing. To investigate the effects of oral stimuli on diet-induced thermogenesis in 11 healthy normal weight males, we conducted a randomized crossover study comprising three trials: (1) drinking liquid food normally, (2) drinking liquid food after tasting, and (3) adding chewing while tasting. Oral stimuli (i.e., the duration of tasting liquid food in the mouth and the duration of chewing) significantly increased diet-induced thermogenesis after drinking liquid food. This result demonstrates that the increase in diet-induced thermogenesis is due to oral stimuli rather than the influence of the food bolus. Increased diet-induced thermogenesis induced by chewing and taste stimuli may help to prevent overweight and obesity.

Metabolic syndrome and masticatory hypofunction: a cross-sectional study

The objective of this paper is to clarify the rate of abdominal obesity (AO), waist-to-height ratio (WHtR), metabolic syndrome (MetS) and determine the relationship with the masticatory capacity (MC) in terms of total functional tooth units (t-FTU) in a representative sample of older Spanish adults. This cross-sectional study included 544 adult subjects aged 50 or over, who were prospectively selected and who had participated in a survey conducted in a primary dental care service in a Public Oral Health Service in Spain. Anthropometric, clinical variables and t-FTUs were obtained through a calibrated and well-established protocol. Univariate and multivariate binary and multinomial logistic regression analyses were developed. With regards to the t-FTU or MC, it was poor in 60.3%, good in 17.6%, and complete in 22.1% of the sample. The univariate odss ratio (OR) for MetS and AO increased as the MC decreased and as the age group increased. With regards to gender, women presented with an OR of 5.56 (CI 95% 3.70-8.38). With regards to the WHtR-a3 (WHtR grouped into three categories), the univariate ORs were all significant for morbid obesity compared to the healthy group, with a risk of 6.86 (CI 95% 3.23-14.58) for patients with poor MC compared to those with complete MC. Masticatory hypofunctionality could be associated with the presence of MetS. Clinical relevance: The number of t-FTUs is directly related to AO.

Chronic Powder Diet After Weaning Induces Sleep, Behavioral, Neuroanatomical, and Neurophysiological Changes in Mice

The purpose of this study is to clarify the effects of chronic powder diet feeding on sleep patterns and other physiological/anatomical changes in mice. C57BL/6 male mice were divided into two groups from weaning: a group fed with solid food (SD) and a group fed with powder food (PD), and sleep and physiological and anatomical changes were compared between the groups. PD exhibited less cranial bone structure development and a significant weight gain. Furthermore, these PD mice showed reduced number of neurogenesis in the hippocampus. Sleep analysis showed that PD induced attenuated diurnal sleep/wake rhythm, characterized by increased sleep during active period and decreased sleep during rest period. With food deprivation (FD), PD showed less enhancement of wake/locomotor activity compared to SD, indicating reduced food-seeking behavior during FD. These results suggest that powder feeding in mice results in a cluster of detrimental symptoms caused by abnormal energy metabolism and anatomical/neurological changes.

The short-term effects of soft pellets on lipogenesis and insulin sensitivity in rats

The purpose of the present study was to investigate the short-term effects of a 12-day, soft pellet (SP) diet with a 3-h restricted feeding schedule on caloric intake, body weight, lipid metabolism, and insulin sensitivity. Glucose and insulin levels were measured pre-, mid-, and post-feeding. The SP rats exhibited postprandial hyperglycemia compared to rats fed control pellets (CP). The insulin response of SP rats during a meal was significantly higher than that of CP rats. There were no significant differences in the hepatic triacylglycerol contents and lipogenesis gene mRNA levels of SP and CP rats. However, the hepatocytes of SP rats were slightly hypertrophic. In addition, histological analysis revealed that the pancreases of SP rats had more islet areas than those of CP rats. This study demonstrated that feeding an SP-only diet for 12 days induces glucose intolerance, suggesting that the consumption of absorbable food, like a soft diet, may trigger glucose metabolism insufficiency and lead to life-threatening diseases.

A review of the effects of nuts on appetite, food intake, metabolism, and body weight

Tree nuts and peanuts are good sources of many nutrients and antioxidants, but they are also energy dense. The latter often limits intake because of concerns about their possible contribution to positive energy balance. However, evidence to date suggests that nuts are not associated with predicted weight gain. This is largely due to their high satiety value, leading to strong compensatory dietary responses, inefficiency in absorption of the energy they contain, a possible increment in resting energy expenditure, and an augmentation of fat oxidation. Preliminary evidence suggests that these properties are especially evident when they are consumed as snacks.

The effects of bilateral lesions of the mesencephalic trigeminal sensory nucleus on nocturnal feeding and related behaviors in mice

AIMS

The mesencephalic trigeminal sensory nucleus (Me5), which receives signals originating from oral proprioceptors and projects its fibers to the hypothalamus, regulates mastication and modulates satiation. Because the Me5 neurons display circadian rhythms in circadian mPer1 gene expression and bilateral Me5 lesions change feeding and exploratory behavior profiles, we speculated that Me5 may influence the daily timing of feeding. Therefore, we explored the effects of bilateral caudal Me5 lesions on the circadian profiles of feeding and its related behaviors.

MAIN METHODS

We measured the activities of feeding, drinking, and locomotion for 24h using an automated feeding behavior measurement apparatus and analyzed the mRNA expression levels of hypothalamic orexigenic and anorexigenic signaling molecules in both Me5-lesioned and sham-operated mice.

KEY FINDINGS

Food and water intake and locomotor activity decreased significantly in Me5-lesioned mice during the dark phase without affecting these total indexes when measured over the entire day. Analysis of the mRNA expression levels of hypothalamic orexigenic and anorexigenic signaling molecules showed that prepro-orexin (orexin) mRNA in the perifornical area was significantly decreased during the dark phase only in Me5-lesioned mice.

SIGNIFICANCE

Bilateral caudal Me5 lesions alter the nocturnal properties of food and water intake and locomotor activity in mice and decrease the mRNA expression level of orexin in the perifornical area during the dark phase. These results suggest that Me5 activity may influence the nocturnal properties of feeding and its related behaviors by adjusting the activity of orexin neurons in the perifornical area.

Oral processing effort, appetite and acute energy intake in lean and obese adults

Chewing reportedly contributes to satiation and satiety signals. Attempts to document and quantify this have led to small and inconsistent effects. The present trial manipulated oral processing effort though required chewing of gums of different hardness and measured appetitive sensations, energy intake, gastric emptying, GI transit time, and concentrations of glucose, insulin, GLP-1, ghrelin and pancreatic polypeptide. Sixty adults classified by sex and BMI (15 each of lean females, obese females, lean males and obese males) were tested in a randomized, controlled, cross-over trial with three arms. They chewed nothing, soft gum or hard gum for 15 min while sipping grape juice (10% of individual energy needs) containing acetaminophen and lactulose on one day each separated by 7 days. Electromyographic recordings and self-reports were obtained during and after chewing to quantify oral processing effort. Blood was sampled through an indwelling catheter and appetite ratings were obtained at baseline and at 0, 15, 30, 45, 60, 90, 120, 180 and 240 min after chewing initiation. Breath samples were collected at 10 min intervals for the first 2h and at 30 min intervals for the next 2h. No effects of chewing were observed for appetitive sensations or gut peptide concentrations. Energy intake tended to decline in lean and increase in obese participants so that daily energy intake differed significantly between the two groups when chewing either gum, while no difference was observed on the non-chewing day. Serum glucose and insulin were significantly lower at selected time points 90-240 min after chewing compared to baseline and the non-chewing day. These data indicate chewing effort does not affect appetitive sensations or gut peptide secretion, but may exert a small differential effect on acute energy intake in lean and obese individuals and lead to greater post-prandial declines of serum glucose and insulin. The efficacy of gum chewing as a substitute for eating for weight management remains uncertain.

Effects of thirty-times chewing per bite on secretion of glucagon-like peptide-1 in healthy volunteers and type 2 diabetic patients

Glucagon-like peptide 1 (GLP-1) is secreted from the small intestine to the blood in response to glucose intake during a meal; however, it is not known whether mastication affects GLP-1 secretion. Here, we examined the relationship between mastication and GLP-1 secretion, along with postprandial blood glucose and insulin concentrations. We compared the levels of blood glucose, serum insulin, and plasma active GLP-1 concentrations after young healthy volunteers ate a test meal either by usual eating (control) or in one of three specified ways: 1. unilateral chewing, 2. quick eating, 3. 30-times chewing per bite. Ten volunteers participated in each of the three groups. Plasma active GLP-1 concentrations did not change by unilateral chewing or quick eating, but did increase by the third method, without affecting the concentrations of blood glucose or serum insulin. Next, we tested whether 30-times chewing per bite increased plasma active GLP-1 concentrations in 15 patients with type 2 diabetes mellitus, but there was no difference in results between usual eating and 30-times chewing per bite. This is a pilot trial with a small number of subjects, but is the first study to investigate the relationships between various styles of mastication and the GLP-1 secretion in young healthy volunteers and type 2 diabetic patients.

Bilateral lesions of the mesencephalic trigeminal sensory nucleus stimulate hippocampal neurogenesis but lead to severe deficits in spatial memory resetting

The mesencephalic trigeminal sensory nucleus (Me5), which receives signals originating from oral proprioceptors, becomes active at weaning and contributes to the acquisition of active exploratory behavior [Ishii, T., Furuoka, H., Kitamura, N., Muroi, Y., and Nishimura, M. (2006) Brain Res. 1111, 153-161]. Because cognitive functions play a key role in animal exploration, in the present study we assessed the role of Me5 in spatial learning and memory in the water maze. Mice with bilateral Me5 lesions exhibited severe deficits in both a reversal learning and a reversal probe test compared with sham-operated mice. In spite of these reversal tests, Me5 lesions had no effect on a hidden platform test. These results suggest that Me5-lesioned mice show a perseveration of the previously learned spatial strategy rather than an inability to learn a new strategy, resulting in reduced spatial memory resetting. Moreover, adult neurogenesis in the dentate gyrus of the hippocampus, which has been proposed to have a causal relationship to spatial memory, was stimulated in Me5-lesioned mice. Thus, a stimulation of hippocampal neurogenesis observed after Me5 lesions may lead to a rigidity and perseverance of the previously learned strategy because of inferential overuse of past memories in a novel situation. These results suggest that Me5 contributes to spatial memory resetting by controlling the rate of hippocampal neurogenesis through an ascending neuronal pathway to the hippocampus.

The mesencephalic trigeminal sensory nucleus is involved in acquisition of active exploratory behavior induced by changing from a diet of exclusively milk formula to food pellets in mice

Post-weaning mice fed exclusively milk display low-frequency exploratory behavior [Ishii, T., Itou, T., and Nishimura, M. (2005) Life Sci. 78, 174-179] compared to mice fed a food pellet diet. This low-frequency exploratory behavior switched to high-frequency exploration after a switch from exclusively milk formula to a food pellet diet. Acquisition of the high-frequency exploratory behavior was irreversible. Recently, we demonstrated that the mesencephalic trigeminal nucleus (Me5) is involved in the control of feeding and exploratory behavior in mice without modulating the emotional state [Ishii, T., Furuoka, H., Itou, T., Kitamura, N., and Nishimura, M. (2005) Brain Res. 1048, 80-86]. We therefore investigated whether the Me5 is involved in acquisition of high-frequency exploratory behavior induced by the switch in diet from an exclusively milk formula to food pellets. Mouse feeding and exploratory behaviors were analyzed using a food search compulsion apparatus, which was designed to distinguish between the two behaviors under standard living conditions. Immunohistochemical analysis of immediate early genes indicated that the Me5, which receives signals from oral proprioceptors, is transiently activated after the diet change. The change from low-frequency to high-frequency exploratory behavior was prevented in milk-fed mice by bilateral lesion of the Me5. These results suggest that the Me5 is activated by signals associated with mastication-induced proprioception and contributes to the acquisition of active exploratory behavior.

The mesencephalic trigeminal sensory nucleus is involved in the control of feeding and exploratory behavior in mice

The mesencephalic trigeminal nucleus (Me5), which receives input from oral proprioceptors and projects to higher brain regions, is involved in mastication-induced modulation of satiation. To investigate how the Me5 is involved in the control of feeding and exploratory behavior, we examined the effect of bilateral electrolytic lesions of the Me5 on feeding and exploratory behavior in mice. Mouse feeding and exploratory behaviors were analyzed using a food-search-compulsion-apparatus (FSCA), which was designed to distinguish between the two behaviors under standard living conditions. To assess anxiety in mice in an unfamiliar environment, exploratory activity was analyzed in an automated hole-board apparatus. Mice with bilateral Me5 lesions had unique feeding and exploratory behavior profiles in the FSCA compared with sham-operated mice. Me5-lesioned mice spent more time in the food chamber during each trial in the FSCA, but the number of entries into the food chamber was decreased by 40% compared to sham-operated mice. Moreover, Me5 lesions markedly inhibited exploratory behavior, manifested as low-frequency exploration. In spite of the low-frequency exploration in the FSCA, Me5 lesions had no effect on various exploratory activities analyzed in the hole-board apparatus, i.e., total locomotor activity, frequency and duration of rearing and head-dipping, and latency to the first head-dipping. These results suggest that the Me5 is involved in the control of feeding and exploratory behavior through its ascending neuronal pathways in mice without modulating the emotional state.

Expressions of CCAAT-enhancer-binding proteins and c-Myc in the parotid gland of the rat: in vivo effects of isoprenaline, bethanechol, vasoactive intestinal peptide and food intake

Parotid glands of adult female rats were exposed to agonists mimicking sympathetic (isoprenaline, 1mg/kg, I.P.) or parasympathetic activity (bethanechol, 10 microg/kg/min i.v. for 30 min, and vasoactive intestinal peptide, VIP, 0.2 microg/kg/min, i.v. for 30 min) or they were reflexly activated by a meal demanding chewing. The stimulated glands were removed at varying times (15(30)-360 min) following the onset of the agonist administration or 75-300 min after the start of a 1h long feeding period, and a number of transcription factors was studied using Western blot. The protein bands were semi-quantitatively measured by densitometry. In response to isoprenaline, C/EBPalpha of 42, 38 and 30 kDa increased by 45-50% above control value, C/EBPbeta LAP (38/35 kDa) by 80% and C/EBPdelta (35 kDa) by 230%, while C/EBPbeta LIP (20 kDa) decreased by 45%. In response to VIP, C/EBPalpha of 42 kDa increased by 75% and C/EBPalpha of 30 kDa by 10%, C/EBPbeta LAP by 65% and C/EBPdelta by 410%, while C/EBPalpha of 38 kDa as well as C/EBPbeta LIP were not changed. In response to bethanechol, C/EBPalpha of 42 kDa increased by 105%, C/EBPbeta LAP by 40% and C/EBPdelta by 170%, while C/EBPalpha of 30 kDa decreased by 30% and C/EBPalpha of 38 kDa and C/EBPbeta LIP remained unchanged. c-Myc increased in response to isoprenaline and VIP by 40-55%, but not to bethanechol. In rats offered a pelleted diet, the parotid glands displayed increases in C/EBPalpha of 42 kDa by 105%, of 30 kDa by 40% and of 38 kDa, by 10%, in C/EBPbeta LAP by 65% and in C/EBPdelta by 215%, whereas C/EBPbeta LIP decreased by 25%. Thus, in parotid glands transcription factors of importance for growth and metabolism were shown to be influenced by autonomimetics as well as by nervous activity.

Food texture differences affect energy metabolism in rats

Dietary factors such as taste and nutrients are known to affect satiety and energy balance. We hypothesized that food texture might contribute to the regulation of energy metabolism through the process of mastication in the oral cavity as well. The effects of long-term feeding of different-textured pellets on body weight gain, adiposity, and thermogenesis were assessed. From weaning at 4 wks, rats were divided into 2 groups fed on either standard (controls) or soft pellets (soft-fed) that required less chewing with the same nutritional composition. At 26 wks, the soft-fed rats showed greater adiposity than did the controls. Daily food intake did not differ between the 2 groups. The increase in body temperature following feeding was significantly lower in the soft-fed rats. These results suggested that food texture affected energy metabolism by changing post-prandial thermogenesis. The long-term deficiency of thermogenesis associated with soft foods resulted in a greater tendency toward obesity.

The hardness of food plays an important role in food selection behavior in rats

To examine the importance of the hardness of foods, we conducted behavioral and electromyographical experiments in Wistar male rats using three kinds of pellets, a hard commercially made pellet (MF), a hard privately produced pellet (H) and a soft privately produced pellet (S). MF and H had the same hardness but contained different ingredients, and S and H had the same ingredients but different degrees of hardness (S<H). In the behavioral experiment, when the rats fed with MF during the 3 weeks following weaning were presented with two types of pellets, S and H, they preferred S to H. On the other hand, the rats fed with powdered MF during the 3 weeks following weaning could not discriminate between S and H on the 1st day of the 6th week. When we compared the EMG activities of the masseter muscle during feeding of S or H pellets, we found that the rats raised on powdered food could not control their muscular power according to the hardness of foods on the first test day; however, rats recovered from this disability after one-day feeding of H and S pellets. After ingestion of either S or H was paired with an intraperitoneal (ip) injection of 0.15 M LiCl (2% of body weight), the animals of both groups avoided the pellets paired with LiCl. However, when the presented pellets were crushed, rats did not discriminate between crushed S and crushed H. These results suggest that the hardness of food plays an important role in the selection and ingestion of food and that the hardness of food could be a conditioned stimulus for conditioned food aversion.

Masticatory function and its effects on general health

One of the main goals of dentistry is to preserve a lifelong healthy masticatory function. Recent studies have shown that mastication is of great importance, not only for the intake of food but also for the systemic, mental and physical functions of the body. The purpose of this review is to compile the latest scientific information concerning the relationship between mastication and general health.

Facilitation of adrenal sympathetic efferent nerve activity induced by mechanical stimulation of teeth in the rat

The effects of afferent signals from the periodontal mechanoreceptors and muscle spindles of jaw-closing muscles on adrenal nerve activity were examined using anesthetized rats. The adrenal nerve activity increased with pressure stimulation of the teeth and by biting a wooden stick. However, after denervation of the periodontal ligament, the facilitation due to the stick-biting was not observed. These results indicate that periodontal afferents facilitate adrenal nerve activity.

Hypothalamic neuronal histamine: implications of its homeostatic control of energy metabolism

In a series of studies on histaminergic functions in the hypothalamus, probes to manipulate activities of histaminergic neuron systems were applied to assess its physiologic and pathophysiologic implications using non-obese normal and Zucker obese rats, an animal model of genetic obesity. Food intake is suppressed by either activation of H1-receptor or inhibition of the H3-receptor in the ventromedial hypothalamus (VMH) or the paraventricular nucleus, each of which is involved in satiety regulation. Histamine neurons in the mesencephalic trigeminal sensory nucleus modulate masticatory functions, particularly eating speed through the mesencephalic trigeminal motor nucleus, and activation of the histamine neurons in the VMH suppress intake volume of feeding at meals. Energy deficiency in the brain, i.e., intraneuronal glucoprivation, activates neuronal histamine in the hypothalamus. Such low energy intake in turn accelerates glycogenolysis in the astrocytes to prevent the brain from energy deficit. Thus, both mastication and low energy intake act as afferent signals for activation of histaminergic nerve systems in the hypothalamus and result in enhancement of satiation. There is a rationale for efficacy of a very-low-calorie conventional Japanese diet as a therapeutic tool for weight reduction. Feeding circadian rhythm is modulated by manipulation of hypothalamic histamine neurons. Hypothalamic histamine neurons are activated by an increase in ambient temperature. Hypothalamic neuronal histamine controls adaptive behavior including a decrease in food intake and ambulation, and an increase in water intake to maintain body temperature to be normally constant. In addition, interleukin-1 beta, an endogenous pyrogen, enhanced turnover of neuronal histamine through prostaglandin E2 in the brain. Taken together, the histamine neuron system in the hypothalamus is essential for maintenance of thermoregulation through the direct and indirect control of adaptive behavior. Behavioral and metabolic abnormalities of obese Zucker rats including hyperphagia, disruption of feeding circadian rhythm, hyperlipidemia, hyperinsulinemia, and disturbance of thermoregulation are essentially derived from a defect in hypothalamic neuronal histamine. Abnormalities produced by depletion of neuronal histamine from the hypothalamus in normal rats mimic those of obese Zuckers. Grafting the lean Zucker fetal hypothalamus into the obese Zucker pups attenuates those abnormalities. These findings indicate that histamine nerve systems in the brain play a crucial role in maintaining homeostatic energy balance.

Lingual factors enhance the increase of ornithine decarboxylase activity in rat jejunal mucosa after feeding

Luminal nutrients are the main factors that stimulate ornithine decarboxylase (ODC) activity in rat intestinal mucosa following feeding. The aim of the present study was to determine whether lingual (oral) factors are related to the increase in jejunal ODC activity after feeding. ODC activity in the jejunum and liver was measured 3 hours after refeeding of 48-hour fasted rats. In the first experiment, rats were refed with a regular pellet, powder, or liquid diet. In the second experiment, rats were infused with the liquid diet through a gastric infusion tube following 48 hours' fasting. In the third experiment, the experimental rats had a gastric fistula that allowed free drainage from the stomach of all ingested liquid diet. In the fourth experiment, a truncal vagotomy was performed 1 week before the experiment. The increase of ODC activity in the jejunum of rats fed with the liquid diet was less than that of rats fed with the pellet diet or powder diet. The increase of ODC activity in the jejunal mucosa of rats infused through the gastric tube was less than that of rats fed per os, and the increase of ODC activity in the liver did not differ between these experimental groups. ODC activity did not increase in rats with a gastric fistula. Vagotomy did not affect the increase of jejunal ODC activity after feeding. In conclusion, the increase of ODC activity after feeding was attenuated in rats in which the diet was given by bypassing the mouth. This indicates that lingual factors enhance the increase of ODC activity in the jejunal mucosa after feeding, but the lingual factors alone do not increase ODC activity in the jejunum.

Histamine receptor and its regulation of energy metabolism

In a series of studies on brain functions of histamine, probes to manipulate activities of histaminergic neuronal systems were applied to assess histaminergic function in non-obese normal, and lean and obese Zucker rats. Food intake was suppressed by both activation of H1-receptors and inhibition of H3-receptors in the ventromedial hypothalamic nucleus (VMH) and the paraventricular nucleus, each of which is a satiety center. Feeding circadian rhythm was decreased in its amplitude through histaminergic modulation in the hypothalamus. Histamine neurons in the mesencephalic trigeminal nucleus (Me5) were involved in regulation of masticatory functions, particularly eating speed, while histamine-containing neurons in the VMH controlled intake volume of meals. Energy deficiency in the brain enhanced satiation through histaminergic activation of VMH neurons, which in turn produced glycogenolysis in the hypothalamus to maintain homoestatic control of glucose supply. A very-low-calorie conventional Japanese diet, which is a fiber rich and low energy food source, enhanced satiation by increased mastication and because of the low energy supply of the diet. Hypothalamic histamine neurons were activated by high ambient temperature and also by interleukin-1 beta, an endogenous pyrogen, to maintain homeostatic thermoregulation. Behavioral and metabolic abnormalities of Zucker obese rats were mediated by a deficit in hypothalamic neuronal histamine, and the Zucker rat was evaluated as an animal model of histamine deficiency. Transplantation of the lean fetal hypothalamus into the third cerebroventricle of host obese Zuckers attenuated the abnormalities.

A very-low-calorie conventional Japanese diet: its implications for prevention of obesity

A very-low-calorie conventional Japanese diet of 370 kcal/day has been shown to be useful for weight reduction and its long-term maintenance. Sources of the diet were mainly from chicken fillet, egg white, fish white-meat, mushroom, seaweed and low- or non-calorie fiber-rich vegetable, and contained 4.4g fat, 38.1g protein, 45.2g carbohydrate and essential minerals and vitamins. However, metabolic and neural implications of a commercial very-low-calorie liquid formula diet have rarely been investigated from the view point of food intake and appetite regulation. Animal studies have demonstrated the rationale for efficacy of the very-low calorie conventional Japanese diet as follows: (1) Increased hypothalamic histamine suppressed food intake through H1-receptors in the ventromedial hypothalamus (VMH) and paraventricular nucleus, the satiety centers. (2) Low energy intake enhanced satiety and decreased food intake through histaminergic activation of VMH neurons. (3) Mastication activated afferent signal transmission from proprioceptors in the oral cavity to the mesencephalic trigeminal nucleus(Me5). Histaminergic systems in the hypothalamus were activated by mastication and low energy supply, which was accompanied by satiation through the action of histamine in the VMH. Usefulness of the very-low-calorie conventional Japanese diet derives from utilization of conventional Japanese food stuffs as a fiber rich, low energy food source, and from enhancement of satiation by increased mastication required of the diet. The properties of the diet seemed to effect a closed positive feedback loop between histaminergic activation in hypothalamic satiety centers and behavioral changes to enhance satiation and cause feeding suppression.