chemistry

Lipofuscin

Lipofuscin is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lipofuscin rather than just read about it. In short: Lipofuscin is the name given to fine yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, retina, adrenals, nerve cells, and ganglion cells.

Key takeaways

Lipofuscin belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Lipofuscin to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lipofuscin from memory before moving on to harder problems.

Reference excerpt

Lipofuscin is the name given to fine yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, retina, adrenals, nerve cells, and ganglion cells.

Formation and turnover

Lipofuscin appears to be the product of the oxidation of unsaturated fatty acids and may be symptomatic of membrane damage, or damage to mitochondria and lysosomes. Aside from a large lipid content, lipofuscin is known to contain sugars and metals, including mercury, aluminium, iron, copper and zinc. Lipofuscin is also accepted as consisting of oxidized proteins (30–70%) as well as lipids (20–50%). It is a type of lipochrome and is specifically arranged around the nucleus. The accumulation of lipofuscin-like material may be the result of an imbalance between formation and disposal mechanisms. Such accumulation can be induced in rats by administering a protease inhibitor (leupeptin); after a period of three months, the levels of the lipofuscin-like material return to normal, indicating the action of a significant disposal mechanism. However, this result is controversial, as it is questionable if the leupeptin-induced material is true lipofuscin. There exists evidence that "true lipofuscin" is not degradable in vitro; whether this holds in vivo over longer time periods is not clear.

The ABCR -/- knockout mouse has delayed dark adaptation but normal final rod threshold relative to controls. Bleaching the retina with strong light leads to formation of toxic cationic bis-pyridinium salt, N-retinylidene-N-retinyl-ethanolamine (A2E), which causes dry and wet age-related macular degeneration. From this experiment, it was concluded that ABCR has a significant role in preventing formation of A2E in extracellular photoreceptor surfaces during bleach recovery.

Relation to diseases

Lipofuscin accumulation in the eye is a major risk factor implicated in macular degeneration, a degenerative disease, and Stargardt disease, an inherited juvenile form of macular degeneration. In the peripheral nervous system, abnormal accumulation of lipofuscin known as lipofuscinosis is associated with a family of neurodegenerative disorders – neuronal ceroid lipofuscinoses, the most common of these is Batten disease. Also, pathological accumulation of lipofuscin is implicated in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, certain lysosomal diseases, acromegaly, denervation atrophy, lipid myopathy, chronic obstructive pulmonary disease, and centronuclear myopathy. Accumulation of lipofuscin in the colon is the cause of the condition melanosis coli. On the other hand, myocardial lipofuscin accumulation more directly reflects chronological ageing rather than human cardiac pathology.

Possible therapies Calorie restriction, vitamin E, and increased glutathione appear to reduce or halt the production of lipofuscin. The nootropic drug piracetam appears to significantly reduce accumulation of lipofuscin in the brain tissue of rats. Other possible treatments:

Centrophenoxine Acetyl-L-carnitine Ginkgo biloba Dimethylethanolamine Curcumin Wet macular degeneration can be treated using selective photothermolysis where a pulsed unfocused laser predominantly heats and kills lipofuscin-rich cells, leaving untouched healthy cells to multiply and fill in the gaps. The technique is also used as a skin treatment to remove tattoos, liverspots, and in general make skin appear younger. This ability to selectively target lipofuscin has opened up research opportunities in the field of anti-aging medicine. Soraprazan (remofuscin) has been found to remove lipofuscin from retinal pigment epithelial cells in animals. This opens up a new therapy option for the treatment of dry age-related macular degeneration and Stargardt disease, for which there is currently no treatment. The drug has now been granted orphan drug designation for the treatment of Stargardt disease by the European Medicines Agency.

Other uses Lipofuscin quantification is used for age determination in various crustaceans such as lobsters and spiny lobsters. Since these animals lack bony parts, they cannot be aged in the same way as bony fish, in which annual increments in the ear-bones or otoliths are commonly used. Age determination of fish and shellfish is a fundamental step in generating basic biological data such as growth curves, and is needed for many stock assessment methods. Several studies have indicated that quantifying the amount of lipofuscin present in the eye-stalks of various crustaceans can give an index of their age. This method has not yet been widely applied in fisheries management mainly due to problems in relating lipofuscin levels in wild-caught animals with accumulation curves derived from aquarium-reared animals.

See also Residual body Advanced glycation end-products (AGEs)

References

20. Young B, Lowe JS, Stevens A, Heath JW. Wheater's Functional Histology: A Text and Atlas. 6th ed. Elsevier

External links for general reviews Terman A, Brunk U (2004). "Lipofuscin". Int J Biochem Cell Biol. 36 (8): 1400–4. doi:10.1016/j.biocel.2003.08.009. PMID 15147719. Histology at neuro.wustl.edu Histology image: 20301loa – Histology Learning System at Boston University Destroying Lipofuscin and Destroying Cancer, FightAging.org Unfocused Pulsed Lasers Selectively Destroy Lipofuscin, AcceleratingFuture.com Lipofuscin

Illustrations

Worked examples

Example 1 — a first encounter with Lipofuscin

Start with the simplest possible case. Write down what Lipofuscin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lipofuscin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lipofuscin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lipofuscin

In research: Lipofuscin appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Lipofuscin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Lipofuscin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Biomolecules, Senescence, so understanding it makes those chapters shorter.
In everyday life: Look for Lipofuscin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Lipofuscin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lipofuscin means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Lipofuscin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lipofuscin in simple terms?

Why does Lipofuscin matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lipofuscin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lipofuscin.