Rats are unable to discriminate quinine from diverse bitter stimuli

Compounds described by humans as “bitter” are sensed by a family of type 2 taste receptors (T2Rs). Previous work suggested that diverse bitter stimuli activate distinct receptors, which might allow for perceptually distinct tastes. Alternatively, it has been shown that multiple T2Rs are expressed on the same taste cell, leading to the contrary suggestion that these stimuli produce a unitary perception. Behavioral work done to address this in rodent models is limited to Spector and Kopka (Spector AC, Kopka SL. J Neurosci 22: 1937–1941, 2002), who demonstrated that rats cannot discriminate quinine from denatonium. Supporting this finding, it has been shown that quinine and denatonium activate overlapping T2Rs and neurons in both the mouse and rat nucleus of the solitary tract (NTS). However, cycloheximide and 6-n-propylthiouracil (PROP) do not appear to overlap with quinine in the NTS, suggesting that these stimuli may be discriminable from quinine and the denatonium/quinine comparison is not generalizable. Using the same procedure as Spector and Kopka, we tasked animals with discriminating a range of stimuli (denatonium, cycloheximide, PROP, and sucrose octaacetate) from quinine. We replicated and expanded the findings of Spector and Kopka; rats could not discriminate quinine from denatonium, cycloheximide, or PROP. Rats showed a very weak ability to discriminate between quinine and sucrose octaacetate. All animals succeeded in discriminating quinine from KCl, demonstrating they were capable of the task. These data suggest that rats cannot discriminate this suite of stimuli, although they appear distinct by physiological measures.

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Targeting angiotensin type-2 receptors located on pressor neurons in the nucleus of the solitary tract to relieve hypertension in mice

Cardiovascular Research ◽

10.1093/cvr/cvab085 ◽

2021 ◽

Author(s):

Mazher Mohammed ◽

Dominique N Johnson ◽

Lei A Wang ◽

Scott W Harden ◽

Wanhui Sheng ◽

...

Keyword(s):

Blood Pressure ◽

Gaba Release ◽

Access Point ◽

Central Administration ◽

Solitary Tract ◽

Arterial Blood ◽

Pressor Responses ◽

Pressure Lowering ◽

Angiotensin Type

Abstract Aims These studies evaluate whether angiotensin type-2 receptors (AT2Rs) that are expressed on γ-aminobutyric acid (GABA) neurons in the nucleus of the solitary tract (NTS) represent a novel endogenous blood pressure-lowering mechanism. Methods and results Experiments combined advanced genetic and neuroanatomical techniques, pharmacology, electrophysiology, and optogenetics in mice to define the structure and cardiovascular-related function of NTS neurons that contain AT2R. Using mice with Cre-recombinase directed to the AT2R gene, we discovered that optogenetic stimulation of AT2R-expressing neurons in the NTS increases GABA release and blood pressure. To evaluate the role of the receptor, per se, in cardiovascular regulation, we chronically delivered C21, a selective AT2R agonist, into the brains of normotensive mice and found that central AT2R activation reduces GABA-related gene expression and blunts the pressor responses induced by optogenetic excitation of NTS AT2R neurons. Next, using in situ hybridization, we found that the levels of Agtr2 mRNAs in GABAergic NTS neurons rise during experimentally induced hypertension, and we hypothesized that this increased expression may be exploited to ameliorate the disease. Consistent with this, final experiments revealed that central administration of C21 attenuates hypertension, an effect that is abolished in mice lacking AT2R in GABAergic NTS neurons. Conclusion These studies unveil novel hindbrain circuits that maintain arterial blood pressure, and reveal a specific population of AT2R that can be engaged to alleviate hypertension. The implication is that these discrete receptors may serve as an access point for activating an endogenous depressor circuit.

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Beneficial Effects of Canagliflozin in Combination with Pioglitazone on Insulin Sensitivity in Rodent Models of Obese Type 2 Diabetes

PLoS ONE ◽

10.1371/journal.pone.0116851 ◽

2015 ◽

Vol 10 (1) ◽

pp. e0116851 ◽

Cited By ~ 21

Author(s):

Yoshinori Watanabe ◽

Keiko Nakayama ◽

Nobuhiko Taniuchi ◽

Yasushi Horai ◽

Chiaki Kuriyama ◽

...

Keyword(s):

Type 2 Diabetes ◽

Insulin Sensitivity ◽

Rodent Models ◽

Beneficial Effects

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Spontaneous Type 2 Diabetic Rodent Models

Journal of Diabetes Research ◽

10.1155/2013/401723 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 22

Author(s):

Yang-wei Wang ◽

Guang-dong Sun ◽

Jing Sun ◽

Shu-jun Liu ◽

Ji Wang ◽

...

Keyword(s):

Diabetes Mellitus ◽

Insulin Resistance ◽

Type 2 Diabetes ◽

Health Care ◽

Animal Models ◽

Rodent Models ◽

Advantages And Disadvantages ◽

Characteristic Features ◽

Type 2 Diabetic

Diabetes mellitus, especially type 2 diabetes (T2DM), is one of the most common chronic diseases and continues to increase in numbers with large proportion of health care budget being used. Many animal models have been established in order to investigate the mechanisms and pathophysiologic progress of T2DM and find effective treatments for its complications. On the basis of their strains, features, advantages, and disadvantages, various types of animal models of T2DM can be divided into spontaneously diabetic models, artificially induced diabetic models, and transgenic/knockout diabetic models. Among these models, the spontaneous rodent models are used more frequently because many of them can closely describe the characteristic features of T2DM, especially obesity and insulin resistance. In this paper, we aim to investigate the current available spontaneous rodent models for T2DM with regard to their characteristic features, advantages, and disadvantages, and especially to describe appropriate selection and usefulness of different spontaneous rodent models in testing of various new antidiabetic drugs for the treatment of type 2 diabetes.

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Rodent models for the study of type 2 diabetes in children (juvenile diabesity)

Pediatric Diabetes ◽

10.1034/j.1399-5448.2002.30307.x ◽

2002 ◽

Vol 3 (3) ◽

pp. 163-173 ◽

Cited By ~ 3

Author(s):

Clayton E. Mathews

Keyword(s):

Type 2 Diabetes ◽

Rodent Models

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Experimentally Induced Rodent Models of Type 2 Diabetes

Animal Models in Diabetes Research ◽

10.1007/978-1-62703-068-7_10 ◽

2012 ◽

pp. 161-174 ◽

Cited By ~ 16

Author(s):

Md. Shahidul Islam ◽

Rachel Dorothy Wilson

Keyword(s):

Type 2 Diabetes ◽

Rodent Models ◽

Experimentally Induced

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“It Is a Full-time Job to Be Ill”: Patient Work Involved in Attending Formal Diabetes Care Among Socially Vulnerable Danish Type 2 Diabetes Patients

Qualitative Health Research ◽

10.1177/10497323211041590 ◽

2021 ◽

pp. 104973232110415

Author(s):

Sofie á Rogvi ◽

Ann Dorrit Guassora ◽

Nina Tvistholm ◽

Gitte Wind ◽

Ulla Christensen

Keyword(s):

Type 2 Diabetes ◽

Social Inequality ◽

Border Zone ◽

Care Organization ◽

Full Time ◽

Organization Of Care ◽

Patient Work ◽

Work Done ◽

Diabetes Patients

Previous research has shown social inequality in type 2 diabetes prevalence and that socially vulnerable type 2 diabetes patients benefit less than average from health services. Based on ethnographic fieldwork carried out between February 2017 and March 2018 in a Danish specialized outpatient clinic, this article focuses on patient work among socially vulnerable type 2 diabetes patients. Through attending to the border zone between formal health care and self-care, we show that patients do a lot of work requiring skills, resources, and initiative, to access and benefit from formal care. This work is complex and implicit in the organization of care. Patients’ social situations, especially their employment situation, complicate getting patient work done. Attending to patient work and implicit tasks in care organization may help us to see how social inequality in type 2 diabetes outcomes develops, and may be combated.

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