The Role of Leptin in the Brain for Catecholamine (TH) Neurons, Serotonin (5HT) Neurons and Orexin Neurons Name
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CHAPTER II: LITERATURE REVIEW
2.1 Introduction
Leptin is a hormone that plays a crucial role in regulation of food intake and in energy homeostasis (1-3). The hormone was initially identified in mutant mice displaying extreme obesity and feeding excessively. A few decades later, it was revealed that the mutant mice had inadequate proper leptin signalling which were attributed to a mutation in either the hormone (ob/ob) or its analogous receptor. Leptin is synthesised from the adipose tissue in proportion to the quantity of adipose tissue present and it is distributed to its main area of action, the hypothalamus, where it targets anorexigenic and orexigenic neurons to facilitate most of the leptin roles, including regulation of food intake (2, 3).
Since it is produced in proportion to body energy reserves (adipose tissue), leptin levels in the circulation can act an excellent indicator of how much energy the body has on reserve. Leptin has a critical role in glucose homeostasis and the metabolic roles of the hormone are facilitated by the binding of leptin to leptin receptor (the long form) and the activation of Janus Kinase 2 (JAK) transducer and the transcription of three pathways (2,3). Leptin also plays crucial role in growth and development, reproduction, and in the maintenance of the body immunity (4, 5). …show more content…
There are reports indicating that acute orexin treatment encourages consumption of food in experimental animals such as rats in the course of light phase, but hardly promotes food consumption in the course of dark phase. The variations can be attributed to the role of the neuropeptide in arousal- the experimental animal ought to be awake for it to eat, thus stimulating arousal in the course of the light cycle would augment the entire food intake and the feeding duration (49, 56, 57).
On the other hand, orexin controls the dopamine signalling, indicating that it might play a crucial role in influencing food intake. As a result, orexin can increase food craving, thus encouraging a person to consume more food. In the past, it was widely held that leptin influences the expression of orexin in LHA (58). Nevertheless, new research indicates that orexin peptides are separate from Ob-Rb expressing neurons in the
Course
College
Tutor
Date
CHAPTER II: LITERATURE REVIEW
2.1 Introduction
Leptin is a hormone that plays a crucial role in regulation of food intake and in energy homeostasis (1-3). The hormone was initially identified in mutant mice displaying extreme obesity and feeding excessively. A few decades later, it was revealed that the mutant mice had inadequate proper leptin signalling which were attributed to a mutation in either the hormone (ob/ob) or its analogous receptor. Leptin is synthesised from the adipose tissue in proportion to the quantity of adipose tissue present and it is distributed to its main area of action, the hypothalamus, where it targets anorexigenic and orexigenic neurons to facilitate most of the leptin roles, including regulation of food intake (2, 3).
Since it is produced in proportion to body energy reserves (adipose tissue), leptin levels in the circulation can act an excellent indicator of how much energy the body has on reserve. Leptin has a critical role in glucose homeostasis and the metabolic roles of the hormone are facilitated by the binding of leptin to leptin receptor (the long form) and the activation of Janus Kinase 2 (JAK) transducer and the transcription of three pathways (2,3). Leptin also plays crucial role in growth and development, reproduction, and in the maintenance of the body immunity (4, 5). …show more content…
There are reports indicating that acute orexin treatment encourages consumption of food in experimental animals such as rats in the course of light phase, but hardly promotes food consumption in the course of dark phase. The variations can be attributed to the role of the neuropeptide in arousal- the experimental animal ought to be awake for it to eat, thus stimulating arousal in the course of the light cycle would augment the entire food intake and the feeding duration (49, 56, 57).
On the other hand, orexin controls the dopamine signalling, indicating that it might play a crucial role in influencing food intake. As a result, orexin can increase food craving, thus encouraging a person to consume more food. In the past, it was widely held that leptin influences the expression of orexin in LHA (58). Nevertheless, new research indicates that orexin peptides are separate from Ob-Rb expressing neurons in the