Sex Differences in Fat Signaling in Obesity Prone and Obesity Resistant Rats”
Publication Date
July 2019
Location
LSU Health Medical Education Building
Document Type
Abstract
Start Date
26-7-2019 9:00 AM
End Date
26-7-2019 12:00 PM
Description
Obesity affects one in every four Americans. The development of obesity is due to many factors including sex, susceptibility, and diet. Dysregulation or variations in orosensory perception can lead to overconsumption of highly palatable, calorically dense foods, which increases the risk for developing obesity. CD36 is a fat receptor found in the oral cavity and is proposed to be the fat taste receptor. Multiple studies support a role for lingual CD36 in fat intake and preference and differences in lingual CD36 expression have been shown in rats that differ in their susceptibility to develop obesity. Fat signals from the tongue are predicted to regulate homeostatic and hedonic signals in the brain. The hypothalamic neuropeptide, QRFP- 26, increases fat intake and is increased by the consumption of dietary fat. GPR103a, the receptor for QRFP, is located in the nucleus accumbens (NAc), a key region for hedonic eating. Therefore, expression levels of lingual CD36 may regulate homeostatic and hedonic eating via the QRFP system. We hypothesize that when fed a high fat diet (HFD), obesity-prone Osborne-Mendel (OM) rats will express higher levels of lingual CD36 mRNA, hypothalamic prepro-QRFP mRNA, and GPR130a mRNA in the NAc compared to obesity-resistant S5B/Pl (S5B) rats. We further hypothesize that male rats will have higher expression levels than female rats and will exhibit higher rates of weight gain. To test this, male and female OM and S5B rats were fed a HFD (60% kcal from fat) for seven weeks. Gene expression in the circumvallate papillae of the tongue (CV), the ventromedial hypothalamus/arcuate nucleus (VMH/ARC), and the NAc were assessed by Real Time PCR. Obesity-prone OM males gain more weight and consume more HFD than obesity-resistant S5B male rat. Additionally, males gain more weight and consume more HFD than females. When fed a HFD, lingual CD36 mRNA expression and GPR103a mRNA levels in the NAc were higher in female rats, compared to male rats. Prepro-QRFP mRNA levels were higher in S5B rats compared to OM rats. These data suggest that females may have an increased sensitivity to dietary fat, which decreases their preference for highly fatty foods and leads to decreased consumption of fat. Future directions include assessing fat taste sensitivity using food choice tests and determining the role of estrogen on fat taste preference.
Recommended Citation
Martin, Corinne M., "Sex Differences in Fat Signaling in Obesity Prone and Obesity Resistant Rats”" (2019). Summer Research Internship Program. 3.
https://digitalscholar.lsuhsc.edu/srip/2019/hs/3
Sex Differences in Fat Signaling in Obesity Prone and Obesity Resistant Rats”
LSU Health Medical Education Building
Obesity affects one in every four Americans. The development of obesity is due to many factors including sex, susceptibility, and diet. Dysregulation or variations in orosensory perception can lead to overconsumption of highly palatable, calorically dense foods, which increases the risk for developing obesity. CD36 is a fat receptor found in the oral cavity and is proposed to be the fat taste receptor. Multiple studies support a role for lingual CD36 in fat intake and preference and differences in lingual CD36 expression have been shown in rats that differ in their susceptibility to develop obesity. Fat signals from the tongue are predicted to regulate homeostatic and hedonic signals in the brain. The hypothalamic neuropeptide, QRFP- 26, increases fat intake and is increased by the consumption of dietary fat. GPR103a, the receptor for QRFP, is located in the nucleus accumbens (NAc), a key region for hedonic eating. Therefore, expression levels of lingual CD36 may regulate homeostatic and hedonic eating via the QRFP system. We hypothesize that when fed a high fat diet (HFD), obesity-prone Osborne-Mendel (OM) rats will express higher levels of lingual CD36 mRNA, hypothalamic prepro-QRFP mRNA, and GPR130a mRNA in the NAc compared to obesity-resistant S5B/Pl (S5B) rats. We further hypothesize that male rats will have higher expression levels than female rats and will exhibit higher rates of weight gain. To test this, male and female OM and S5B rats were fed a HFD (60% kcal from fat) for seven weeks. Gene expression in the circumvallate papillae of the tongue (CV), the ventromedial hypothalamus/arcuate nucleus (VMH/ARC), and the NAc were assessed by Real Time PCR. Obesity-prone OM males gain more weight and consume more HFD than obesity-resistant S5B male rat. Additionally, males gain more weight and consume more HFD than females. When fed a HFD, lingual CD36 mRNA expression and GPR103a mRNA levels in the NAc were higher in female rats, compared to male rats. Prepro-QRFP mRNA levels were higher in S5B rats compared to OM rats. These data suggest that females may have an increased sensitivity to dietary fat, which decreases their preference for highly fatty foods and leads to decreased consumption of fat. Future directions include assessing fat taste sensitivity using food choice tests and determining the role of estrogen on fat taste preference.
Comments
Mentor: Stefany Primeaux, PhD, Department of Physiology; Joint Diabetes, Metabolism, and Endocrinology Program