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Glossary of terms

Adipokines

Molecules synthesized and secreted by adipose tissue.

Agonist

A substance that activates a particular receptor to induce a response

Alpha Melanocyte Stimulating Hormone

One of the melanocyte stimulating hormones. It is released from POMC neurones in the arcuate nucleus and is a potent inhibitor of appetite. It also plays a role in other physiological processes such as reproducitve behaviour.

Antagonist

A drug that counteracts the effects of another drug.

Aromatase

An enzyme responsible for the production of oestrogen from an androgen

Body temperature theory

Body temperature acted as the signal to the central nervous system controlling food intake.

Competitively

A substance that competes with another for binding sites

Db/db

Mice that are leptin resistant due to a defective leptin receptor.

Effector hormone

The hormone released upon stimulation by a releasing hormone, that causes the specific action eg growth hormone, released by growth hormone releasing hormone.

Fenfluramine

Was released as an anti-obesity drug in the 1970’s.  This drug acted to increase central serotonin levels and also caused the sensation of fullness and a loss of appetite.

Glucostatic theory

Plasma glucose levels regulated food intake.

Green Fluorescent Protein (GFP)

Derived from the jellyfish Aequora victoria fluoresces when exposed to blue light. The GFP gene can be incorporated into another animal's genome so that it can act as a reporter of gene expression.

Hepatocytes

Liver cells

Homology

Similarity in the genetic make up between organisms caused by a common evolutionary pathway.

JAK STAT Pathway

Janus kinase and signal transducer and activator of transcription pathways activated by leptin and involved in regulation of its target genes.

Lesion experiments

A very old and very well practiced method in which a specific brain region is destroyed.  The site for lesioning can be identified using a form of ‘brain map’ called a stereotaxic map.  Lesions can vary from destroying wide areas of brain tissue using an electrolytic lesion where neural tissue is destroyed with an electrical current, or using neurochemical lesions where very precise areas only can be destroyed using a neurotoxin – a toxin specific to nerve cells.

Lipodystrophy

A medical condition where the adipose tissue degenerates causing leptin deficiency. Patients are ravenously hungry all the time but do not put on weight. Leptin replacement therapy is a very effective cure

Lipogenesis

The formation of fat in the body

Lipostatic theory

A circulating factor was released which travelled to the central nervous system signalling regarding energy requirements.

Mimetic

Having the same action or effect of another substance

mRNA

Messenger RNA that copies the nuclear DNA and then transports the genetic information to the cell cytoplasm where it acts as a template for protein synthesis

Neuroendocrine organ

An organ containing specialised nerve cells that produce hormones. There hormones are secreted into the bloodstream upon stimulation.

Null mice

Mice deficient in both copies of a gene

ob/ob mice

The ob/ob-/- mice are a mutant strain of mice characterized by morbid obesity and hyperphagia.  They are deficient in the ob gene.  They arose at random in a colony of mice in the 1950s and have proved invaluable in the study of obesity.  The ob gene was identified in 1994 and is now called leptin, a circulating adiposity signal.

Oestrogen

A steroid hormone, produced primarily by the ovary. It promotes sexual behaviour and is needed for the development of female characteristics.

Orexigenic

Stimulate hunger

Parabiosis

A very intricate and delicate experiment where the circulatory systems of 2 separate animals (usually mice) are joined.  This can also occur naturally in the form of Siamese twins.

Phentermine

The drug worked by stimulating the release of catecholamines thereby inducing the ‘fight or flight’ response and also causing the loss of appetite. 

Releasing hormone

A hormone that controls the release of another hormone. eg. Growth hormone releasing hormone controls the release of growth hormone. Growth hormone is the effector hormone.

Serine Protease

An enzyme that cleaves the peptide bonds in proteins. This protease is characterised by the presence of a serine residue

Transgenic mice

A mouse that has had a foreign sequence of DNA incorporated into their genome. This DNA may alter the function of the organisms normal genetic code, or may produce mRNA and proteins as normal. This transgene can be passed onto the next generation if it is expressed in the germ cells.

Vagal Afferents

Innervations from the nervous system to the gut, needed for neural communication between the brain and gut

 
   
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