Feminization and Alteration of <Emphasis Type="Italic">Drosophila</Emphasis> Taste Neurons Induce Reciprocal Effects on Male Avoidance Behavior

Taste perception allows most animals to find edible food, potential mates, and avoid ingesting toxic molecules. Intriguingly, a small group of Drosophila taste neurones (expressing Gr66a-Gal4) involved in the perception of bitter substances is also used to detect 7-tricosene (7-T), a male cuticular pheromone. Male flies tend to be inhibited by 7-T whereas females are stimulated by this pheromone. To better understand their role on male courtship, Gr66a-Gal4 neurons were genetically feminized or altered with various transgenes, and the response of transgenic males was measured toward live targets carrying various amounts of 7-T, or of bitter molecules (caffeine, quinine and berberine). Surprisingly, tester males with feminized taste neurons showed an increased dose-dependent avoidance toward targets with high level of any of these substances, compared to other tester males. Conversely, males with altered neurons showed no, or very little avoidance. Moreover, the surgical ablation of the sensory appendages carrying these taste neurons differently affected the behavioral response of the various tester males. The fact that this manipulation did not affect the courtship toward control females nor the locomotor activity of tester males suggests that Gr66a-Gal4 neurons are involved in the sex-specific perception of molecules inducing male avoidance behavior. Edited by Yong-Kyu Kim.     

Relationships of beta-blockers and anxiolytics intake and salivary secretion, masticatory performance and taste perception

Objective

Assess the influence of salivary flow on physiological parameters of the stomatognathic system in patients who take beta-blockers or anxiolytic medications.

Design

Sixty patients were divided into three groups based on the following criteria: Group 1, control (n = 20; no use of medication); Group 2, use of antihypertensive beta-blockers (n = 20); and Group 3, use of benzodiazepine anxiolytics (n = 20). Salivary flow was assessed by determining stimulated and non-stimulated flow/minute. The quantification of the sense of taste was determined on a visual analogue scale (VAS) using solutions of 0.9% NaCl (salty), 50% sucrose (sweet), 20% unsweetened coffee (bitter) and 4.2% vinegar (sour). The DMFT index (number of decayed/missing/filled teeth) was determined by a calibrated examination, following the criteria of the World Health Organization (WHO). Masticatory performance was assessed with an Optosil comminution test and Rosim-Ramler equation.

Results

The results did not reveal a significant correlation between salivary flow and masticatory performance (p > 0.05). We observed significant decreased non-stimulated salivary flow for Group 2 (p = 0.05) when compared to controls. However, taste perception was not influenced by salivary secretion amongst groups. Furthermore, we observed a significant negative correlation between non-stimulated salivary flow and DMFT in Group 1 (p = 0.02; r = −0.52).

Conclusions

Patients under beta-blockers therapy presented reduced non-stimulated salivary flow when compared to controls, without influencing the sense of taste or masticatory performance. The use of anxiolytics did not affect salivary flow and taste perception in the studied sample.     

Measurement of affective state during chronic nicotine treatment and withdrawal by affective taste reactivity in mice: The role of endocannabinoids

Despite tobacco being highly addictive, it is unclear if nicotine has significant affective properties. To address this, we studied taste reactions to gustatory stimuli, palatable sucrose and unpalatable quinine, which are believed to reflect ongoing affective state. Taste reactivity was assessed during chronic nicotine administration and spontaneous withdrawal and the role of the endogenous cannabinoids was also investigated. C57BL6J mice were implanted with intraoral fistula to allow passive administration of solutions. In the first study, taste reactivity was tracked throughout chronic vehicle or nicotine (12 mg/kg/day) infusion via osmotic minipumps and spontaneous withdrawal following removal of minipumps. In the second study, the endocannabinoid CB1-receptor antagonist AM251 (1, 3 and 10 mg/kg, intraperitoneal) or vehicle was acutely administered before taste reactivity measurement during chronic nicotine administration. Chronic nicotine treatment and spontaneous withdrawal did not influence taste reactions to sucrose or quinine. AM251 decreased positive reactions to sucrose and increased negative reactions to quinine. The effects of AM251 were respectively attenuated and enhanced in nicotine infused mice. These results suggest chronic nicotine exposure and withdrawal has no apparent affective sequelae, as probed by taste reactivity, and thus may not explain the difficulty tobacco-users have in achieving abstinence. In contrast, endocannabinoids elevate affective state in drug-naïve animals and changes in endogenous endocannabinoid tone may underlie compensations in affective state during chronic nicotine exposure.     

Gustatory hedonic value: potential function for forebrain control of brainstem taste processing

Among well-nourished populations, eating beyond homeostatic needs when presented with caloric-dense palatable food evidences the assertion that an increasing proportion of consumption is driven by pleasure, not just by the need for calories. This presents a major health crisis because the affective component of foods constitutes a behavioral risk factor that promotes over consumption [Sorensen, L.B., Moller, P., Flint, A., Martens, M., Raben, A., 2003. Effect of sensory perception of foods on appetite and food intake: a review of studies on humans. Int. J. Obes. Relat. Metab. Disord. 27, 1152-1166; Yeomans, M.R., Blundell, J.E., Leshem, M., 2004. Palatability: response to nutritional need or need-free stimulation of appetite? Br. J. Nutr. 92 (Suppl. 1), S3-S14]. Overweight or obese individuals have an increased risk of developing hypertension, stroke, heart disease, chronic musculoskeletal problems, type-2 diabetes, and certain types of cancers [Hill, J.O., Catenacci, V., Wyatt, H.R., 2005. Obesity: overview of an epidemic. Psychiatr. Clin. N. Am. 28, 1-23, vii]. The etiology of obesity is complex involving genetic, metabolic, and behavioral factors, but ultimately results from long-term energy imbalance. Evidence indicates that learned and some forms of unlearned control of ingestive behavior driven by palatability (i.e. hedonic value) are critically dependent on reciprocal interactions between brainstem gustatory nuclei and the ventral forebrain. This review discusses the current understanding of centrifugal control of taste processing in subcortical gustatory nuclei and the potential role of such modulation in hedonic responding.     

Fluctuating gustatory disturbance and ophthalmodynia heralding the onset of a paramedian pontine infarction

Lasting taste disturbance has been previously reported as a consequence of brainstem infarction, but there are no previous reports of transient gustatory sensations preceding the onset of stroke. Ophthalmodynia, presenting as “salt-and-pepper” eye pain, has been reported rarely. We present a 58-year-old right-handed woman who had fluctuating ophthalmodynia and taste disturbance immediately preceding a left paramedian pontine infarction. We discuss the neuroanatomical basis of taste in reference to this presentation.     

《神农本草经》“延年”药物特点分析

目的：归纳《神农本草经》所载具有“延年”功效的药物，总结《神农本草经》“延年”用药学术思想。方法：收集和整理《神农本草经》里明确记载的具有养生功效的药物，通过数据分析该类药物的性味规律及现代分类方法，归纳其药性特点和药物功效分布现状。结果：在药性方面，平性药有60种，占比最高，温热药次之有42种，寒凉药最少有40种；在药味方面，甘味药比例最高有59种，其次为苦味药48种，辛味药有27种，酸、咸味药较少；在现代药物分类方面，高频药类（≥10)为补益药和利水渗湿药两种。结论：发现《神农本草经》“延年”药物多见于上品类，其药多性平味甘，功效特点以补益为主，兼有利水渗湿等功效。《神农本草经》“延年”药物的研究可为总结提炼古代养生药物特点及现代功效演变状态，为现代养生用药提供一定参考和启示。     

Preparation of Various Solid-Lipid Beads for Drug Delivery of Enrofloxacin

Solid-lipid beads were prepared to retard the release rate of enrofloxacin and to mask its bitter taste using carrageenan or sodium alginate as a shell material and either cacao butter or Witepsol W-35 as a solid lipid core. Sodium alginate was a better shell material than carrageenan and the highest loading efficiency was obtained using 2% sodium alginate. The alginate beads had a spherical morphology and a sturdy shell structure. The enrofloxacin release rate at room temperature was greatly reduced. Solid-lipid beads have the potential to mask the bitter taste of enrofloxacin and extend its release rate.     

Salt taste sensitivity threshold and exercise-induced hypertension

Salt taste sensitivity is the capacity to identify the flavour of salt. It is possible that salt taste sensitivity threshold (STST) can influence salt appetite, and sodium ingestion is associated with hypertension. The present study evaluates the relationship between salt taste sensitivity threshold (STST) and blood pressure (BP) response to exercise during a treadmill stress test. Two hundred and three normotensive individuals undergoing evaluation before starting an exercise training program were tested for STST, using concentrated saline solutions from 0.22 to 58.4 g/L. Patients were divided into two groups according to the STST: normal (n-STST) and increased (i-STST); and into two groups according to their BP response to exercise: exercise-induced hypertension (EIH) or physiological blood pressure response (n-EIH). EIH was detected in 49 (24.1%) individuals. Initial systolic and diastolic BP and their areas under the curves during the test were higher in the EIH group. Initial systolic and diastolic BP areas under the curves were significantly higher in i-STST than n-STST. There was an association between STST of at least 1.8 g/L (increased STST) and EIH (OR = 6.71, 95% CI 1.5–29.99) independent of gender, body mass index and age. Occurrence of EIH was associated to i-STST, suggesting that a relationship between high STST and increased BP response to exercise is possible.     

Naltrexone Treatment Increases the Aversiveness of Alcohol for Outbred Rats

Acute naltrexone treatments (0.0, 0.5, 1.0, or 3.0 mg/kg body weight) were administered to separate groups of rats and alcohol taste reactivity and consumption were measured. Rats were given daily naltrexone injections and then tested for taste reactivity to 10% alcohol 30 and 60 min after injection. Each reactivity trial (total of 4) was 60 sec during which 1 ml of fluid was infused. The rats' orofacial and body movements were videotaped and scored later. In the final measure, rats were placed on a restricted fluid access schedule and given naltrexone treatments 10 min before being presented with the 10% alcohol solution in the home cage (60–min drinking period). After 4 days of consumption tests under the drug condition, the rats were given 4 more daily tests without the drug. Results indicated that the two highest naltrexone doses significantly decreased ingestive responding and increased aversive responding, particularly at the 30–min test. Both the 1.0 and 3.0 mg/kg body weight doses also significantly decreased alcohol consumption as measured during the free access tests. Alcohol consumption returned to control levels immediately after the drug treatments were stopped. The data show that dosages of naltrexone 1.0 mg or higher significantly alter both alcohol taste reactivity (increased aversiveness and decreased palatabil-ity) and alcohol consumption (decreased intake) in outbred rats. These results are discussed in relation to naltrexone treatment as a means for decreasing alcohol use and abuse.     

Cross-adapted salt responses in the mouse taste cell

The exact nature of taste adaptation is not known. Intracellular recordings from taste receptor cells are appropriate to clarify cellular adaptation properties. I approached the study of the sugar and salt receptor mechanisms of mammalian taste cells with cross-adaptation experiments. Sucrose pre-adaptation suppresses the cross-adaptation responses to salts. The results show that the taste adaptation is located in the taste receptor cell.