Netflix has released a new series called Sweet Tooth, based on the comic book series of the same name by Jeff Lemire. The series follows the lives of hybrid babies – half human and half animal – who seek to find freedom. The main plot takes place a decade after the collapse of human civilization. As the remaining human survivors attempt to find a cure, the hybrids try to find a way to live free from their animal nature.
Genetic variation causes bitter perception by humans
Genetic variation in taste receptors has been associated with individual differences in bitter perception. Individual differences are often specific to particular bitter compounds, and have been shown to be heritable. In mice, genetic variation in one bitter receptor (hT2R43W35) predicted sensitivity to bitter compounds at a specific concentration. Genetic variation at this receptor locus also changed responses to cell-based assays.
The PTC gene, which codes for taste receptors, has two common forms and five rare variants. Each code for a slightly different shape bitter taste receptor protein. This shape determines the strength of binding between the receptor protein and the bitter compound PTC. Humans have two copies of each gene, and the bitter receptor protein is physically clustered on the chromosomes. Genetic variations in the bitter taste receptor gene are associated with the intensity and taste of PTC. Genetic variation in the PTC gene can also cause variations in the perception of other bitter substances, including toxins.
Recent discoveries have focused attention on differences in taste perception among humans and other species. While some people are highly sensitive to certain bitter compounds, others have a relatively poor or indifferent response to the same sweet substances. In contrast, cats and dogs do not detect sweet substances. Thus, genetic variation is responsible for the difference in taste perception between humans and other species.
Some genetic variation in taste receptors is associated with ethnicity. Africans, for example, show a high level of genetic and geographic diversity. However, these differences in taste perception are not fully understood. While these differences can be heritable, there is no way to predict whether one gene is inherited more than another. It is important to understand the genetics behind differences in human taste perception.
The study examined the frequencies of taste receptor gene variants (LOF) in humans and compared them to those of genes in the human genome. They also compared these frequencies to the frequencies of genes in the olfactory systems. The results suggest that genetic variation in taste perception is heritable and can be explained by combinations of genes.
Effects of age and sex on appetitive behavior
Effects of age and sex on the acquisition and maintenance of appetitive behaviors were investigated in a laboratory setting. Females responded more quickly to appetitive-only than aversive-only tasks, and their responses were affected by the task type. Females tended to experience an enhanced arousal level when given restraint, and their responses were impaired to the tonality-signaled aversive task.
Age and sex were not related to latency to feed in the home cage, but both genders were significantly affected by novel environments. However, the effects on feeding behavior were more variable. The female was socially isolated during adolescence and adulthood. Her food acquisition rate was greater during dark and less refractory to reward devaluation than that of the males.
The experimental setup included adult Sprague-Dawley rats weighing between 175-275 g and 250-350 g. The animals were housed individually and kept at 85% of their free-feeding weight for the duration of the experiment. Prior to training, the rats were weighed, and their food consumption was recorded. The training was performed for two consecutive days.
The study also examined the influence of stress on eating behavior. Stress eating is the process of eating when a person is not hungry, but does so out of emotional reasons. The neural pathways that control stress eating remain unclear. This is largely because there are few good animal models that simulate stress-induced eating behavior. Furthermore, female rodents are typically excluded from these studies because hormonal cycles may disrupt the experiment.
The results also revealed that young animals were less likely to reach the appetitive criterion than older, restrained animals. In the lower left graph, the response latencies of control and restrained males and females were compared. The results showed that males were faster than females, while females took a little longer to reach the criterion.
Effects of leptin concentration on sweet preference
The hormone leptin is responsible for regulating our sweet taste thresholds, and its levels may affect how we perceive the sweetness of foods. Several studies have shown that circulating leptin levels may influence the basal response to sweet taste in mice and humans. Some of these studies also suggest that endogenous leptin may regulate sweet taste thresholds in humans and mice by modulating the Ob-Rb receptor.
This suggests that leptin has a role in reducing food intake by inhibiting the responses of taste cells to sweet compounds. In addition, endocannabinoids, which act through the cannabinoid CB1 receptors, enhance the responses of mice to sweet tastes. However, their respective roles in the regulation of sweet taste are still poorly understood.
In one study, researchers found that salivary leptin concentrations were correlated with sweet and bitter taste sensitivity in young boys. The researchers also observed that higher leptin concentrations in obese children were associated with higher perceptions of bitter taste. However, a consensus has not been reached on the relationship between leptin concentration and bitter taste in humans.
The researchers also found that the serum leptin concentrations decreased in obese females during a weight-loss program. This reduction in the concentration of leptin in the blood may correlate with the decreased sweet taste threshold. The findings suggest that leptin concentrations and sweet taste thresholds are closely related in humans.
This study was a first attempt to test the effects of leptin on sweet taste. In this study, LA at a concentration of two milligrams per kilogram blocked leptin action in a dose that induced a 140 percent increase in the responses to sweet compounds. This effect was significant in both one-way ANOVA and two-way factorial analysis of variance.
There are several hypotheses regarding the relationship between leptin concentration and sweet taste responsiveness. The researchers have also examined the relationship between leptin and insulin resistance. Some studies have suggested that adiposity and insulin resistance may influence the development of sweet taste responsiveness.
Simple recipes to satisfy a sweet tooth
Snacking on simple recipes for desserts is a great way to satisfy your sweet tooth without consuming too much sugar or fat. There are many delicious options for sweet treats, including cookies, bars, and pies. Whether you have a sweet tooth or not, there’s something for everyone.
