Metabolism and the Hypothalamus

           The hypothalamus is an extremely vital organ involved in automatic bodily functions.  It regulates the autonomic nervous system (including automatic and/or subconscious).  Neurons in the hypothalamus produce hypothalamic neurotransmitters, which deliver information and instructions to all parts of the human body. (The role of the hypothalamus in hunger).  The hypothalamus is a integral part of “homeostasis regulation, thirst and hunger cues, body temperature, water balance, blood pressure, and links the nervous system to the endocrine system” (Farr, G).

There are three regions of the hypothalamus that are a part of the production of hunger cues.  These include:  the lateral hypothalamus (responsible for hunger recognition), the ventromedial hypothalamus (responsible for recognizing when a person is full), and the paraventricular hypothalamus (Responsible for the control of hunger).  Each of these hypothalamus regions produce hypothalamus neurotransmitters and neurohormones, which control the delivery of instruction that activate a specific body function.  The hypothalamus primarily produces ghrelin and leptin, which signals/relays that the body is hungry or full. 

          

     Ghrelin:  Ghrelin is a fast acting hormone that regulates feeding behavior and the body’s energy balance by increasing hunger feelings.  This can be validated by examining studies that show an increase in plasma ghrelin concentration in fasting adults.  Also, other subjects participating in the study, were injected with ghrelin experienced extreme hunger.  The secretion of ghrelin begins when blood sugar levels drop, a result of not eating for an extended period of time.  “The hypothalamus receives the message through glucostatic receptors”, (Nakate, S).  The low blood sugar triggers/stimulates the secretion of ghrelin, which results in feelings of hunger.  There is speculation that some obesity cases are related to abnormally high levels of ghrelin secretion, which would not only increase hunger, but also “suppress fat utilization in adipose tissue” (Farr).  After eating, the ventromedial hypothalamus will recognize when blood sugar levels begin to rise to normal levels, and leptin is synthesized, causing fullness feelings to be experienced and release of ghrelin decreases.

     Leptin:  Leptin is a fat hormone (produced by adipose cells), responsible for long- term energy regulation.  Leptin mediates fullness feelings, by triggering the activation of anorectic nerve cells, which begin to synthesize appetite-suppressing neuropeptides.  Scientific evidence points to the theory that people who suffer from obesity are leptin-resistant or leptin-deficient.

Active research in the area of neurotransmitters and neurohormones is at the forefront in the subject weight-control.  If there is a way to control the secretion of ghrelin and leptin, some people struggling with weight maintenance may successfully regain bodily health and normal hunger/fullness cues.

References.

Farr, G. (2002). The hypothalamus. The Nervous System-Advanced Version.  Retrieved from http://www.becomehealthynow.com/article/bodynervousadvanced/956/.

Nakate S. (2010). Hypothalamus Function. Buzzle.com. Retrieved from http://www.buzzle.com/articles/hypothalamus-function.html.

The role of the hypothalamus in hunger. (2010). Hellolife:  Matching Your Commitment to a Healthy Lifestyle. Retrieved from http://www.hellolife.net/explore/weight-loss/the-role-of-the-hypothalamus-in-hunger/.

Klok MD, Jakobsdottir S, Drent ML. (2007). The role of leptin and ghrelin in the regulation of food intake and body weight in humans. Pubmed.  Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/17212793.