Examination of nicotine and saccharin reward in the Goto-Kakizaki diabetic rat model

Diabetes mellitus and female sexual response: what do animal models tell us?

BACKGROUND

One of the less explored effects of diabetes mellitus (DM) is female sexual dysfunction. Females of different species have been used as models.

AIM

To analyze the information of animal models of DM and female sexual response (FSR).

METHODS

The literature of FSR in models of DM was reviewed.

OUTCOMES

Paradigm- and diabetes-dependent changes have been found in various aspects of the FSR.

RESULTS

Females in a type 1 DM (DM1) model show a decrease in the number of proestrus events, and ovariectomized females treated with sex hormones have been used. In these females, a reduction in lordosis has been reported; in proceptivity, the data are contradictory. These females present a decrease in sexual motivation that was restored after exogenous insulin. In the type 2 DM (DM2) model, females show regular estrous cycles, normal levels of lordosis behavior, and, depending on the paradigm, decreased proceptivity. These females display normal preference for sexually active males or their olfactory cues when having free physical contact; they lose this preference when tested in paradigms where physical interaction is precluded.

CLINICAL TRANSLATION

Preclinical data showing the high deleterious effects of a DM1 model and the less drastic effects under a DM2 model are in accordance with clinical data revealing a much higher prevalence of sexual dysfunction in women with DM1 than DM2.

STRENGTHS AND LIMITATIONS

The main strength is the analysis of the changes in various components of FSR in 2 models of DM. The main limitation is the difficulty in extrapolating the data on FSR from rats to women and that most studies focus on evaluating the impact of severe or chronic-moderate hyperglycemia/hyperinsulinemia on the sexual response, without considering other pathophysiologic alterations generated by DM.

CONCLUSION

Females with severe hyperglycemia have a decrease in FSR, while those with moderate hyperglycemia show much less drastic effects.

Quantifying conditioned place preference: a review of current analyses and a proposal for a novel approach

Conditioned place preference (CPP) is used to measure the conditioned rewarding effects of a stimulus, including food, drugs, and social interaction. Because various analytic approaches can be used to quantify CPP, this can make direct comparisons across studies difficult. Common methods for analyzing CPP involve comparing the time spent in the CS+ compartment (e.g., compartment paired with drug) at posttest to the time spent in the CS+ compartment at pretest or to the CS- compartment (e.g., compartment paired with saline) at posttest. Researchers can analyze the time spent in the compartment(s), or they can calculate a difference score [(CS+post - CS+pre) or (CS+post - CS-post)] or a preference ratio (e.g., CS+post/(CS+post + CS-post)). While each analysis yields results that are, overall, highly correlated, there are situations in which different analyses can lead to discrepant interpretations. The current paper discusses some of the limitations associated with current analytic approaches and proposes a novel method for quantifying CPP, the adjusted CPP score, which can help resolve the limitations associated with current approaches. The adjusted CPP score is applied to both hypothetical and previously published data. Another major topic covered in this paper is methodologies for determining if individual subjects have met criteria for CPP. The paper concludes by highlighting ways in which researchers can increase transparency and replicability in CPP studies.

Shenqi compound ameliorates type-2 diabetes mellitus by modulating the gut microbiota and metabolites

The gut microbiota (GM) and metabolites are important factors in mediating the development of type-2 diabetes mellitus (T2DM). An imbalance in the gut microbiota and metabolites can disrupt the function of the intestinal barrier, cause changes in the permeability of the intestinal mucosa and promote the immune inflammatory response, thereby aggravating the fluctuation of blood glucose level and promoting the occurrence and development of the chronic complications of DM. Manipulating the GM and metabolites is a promising therapeutic intervention and is being studied extensively. Shenqi compound (SQC) is a traditional Chinese medicine formulation, which has been widely used to improve T2DM. Studies have demonstrated that SQC can reduce glycemic variability, alleviate the inflammatory response, etc. However, its underlying mechanism remains unknown. Therefore, in this experiment, We administered SQC to Goto-Kakizaki (GK) rats and evaluated its effect on blood glucose homeostasis and the intestinal mucosal barrier. We identified the profiles of the GM and metabolites with the aid of 16S rDNA gene sequencing and non-target metabolomics analysis. It showed that SQC intervention could reduce glycemic variability, regulate serum levels of glucagon and insulin, and improve injury to the intestinal mucosal barrier of GK rats. In the gut, the ratio of bacteria of the phyla Bacteroidetes/Firmicutes could be improved after SQC intervention. SQC also regulated the relative abundance of Prevotellaceae, Butyricimonas, Bacteroides, Blautia, Roseburia, Lactobacillus, and Rothia. We found out that expression of 40 metabolites was significantly improved after SQC intervention. Further analyses of metabolic pathways indicated that the therapeutic effect of SQC might be related predominantly to its ability to improve gluconeogenesis/glycolysis, amino acid metabolism, lipid metabolism, citrate cycle, and butanoate metabolism. These results suggest that SQC may exert a beneficial role in T2DM by modulating the GM and metabolites in different pathways.

Converging vulnerability factors for compulsive food and drug use

Highly palatable foods and substance of abuse have intersecting neurobiological, metabolic and behavioral effects relevant for understanding vulnerability to conditions related to food (e.g., obesity, binge eating disorder) and drug (e.g., substance use disorder) misuse. Here, we review data from animal models, clinical populations and epidemiological evidence in behavioral, genetic, pathophysiologic and therapeutic domains. Results suggest that consumption of highly palatable food and drugs of abuse both impact and conversely are regulated by metabolic hormones and metabolic status. Palatable foods high in fat and/or sugar can elicit adaptation in brain reward and withdrawal circuitry akin to substances of abuse. Intake of or withdrawal from palatable food can impact behavioral sensitivity to drugs of abuse and vice versa. A robust literature suggests common substrates and roles for negative reinforcement, negative affect, negative urgency, and impulse control deficits, with both highly palatable foods and substances of abuse. Candidate genetic risk loci shared by obesity and alcohol use disorders have been identified in molecules classically associated with both metabolic and motivational functions. Finally, certain drugs may have overlapping therapeutic potential to treat obesity, diabetes, binge-related eating disorders and substance use disorders. Taken together, data are consistent with the hypotheses that compulsive food and substance use share overlapping, interacting substrates at neurobiological and metabolic levels and that motivated behavior associated with feeding or substance use might constitute vulnerability factors for one another. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.