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A Seminar onTaurine Deficiency in
Cats
Group 10
March 3, 2014
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Biochemistry of Taurine
Figure 1. Chemical structure of taurine
IUPAC name : 2-aminoethanesulfonic acid
Taurine is an sulfonic acid containing an amino group, yet it is not an amino acid as it is often called one, because it lacks a carboxyl group.
Biosynthesis of Taurine
A dietary deficiency of vitamin B6 shows a depressing effect on taurine biosynthesis.
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Methionine
Cystein
Cysteine sulfunic
acid
Cysteic acid
Hypotaurine
Cysteamine
Taurine
Phosphopantothenate
TransulfurationVit
Cysteine sulfinate decarboxylase
Hypotaurinedecarboxylase
Cysteamine dioxygenaseCysteine
dioxygenase (CDO)
Cysteine sulfinic acid dehydrogenase
Cysteine sulfinate decarboxylase
Cysteine sulfinic acid
pathway
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Taurine Transport in the Body
Taurine transport across cell membrane
• Na+ - dependent taurine transporter
Taurine release from the cell via three mechanisms
- Exocytosis occurs at basal membrane
- Energy-dependent transporter
- Ca2+ - dependent transport
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Taurine
syste
m
Visual
systemImmu
ne syste
m
Renal syste
m
Cardiovascular
Physiological Function of Taurine
Bile acidconjugation
Nervous system
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Roles of Taurine in Nervous System
• Taurine acts as a neurotransmitter.
- Its ability to elicit neuronal hyperpolarization.
- The presence of specific taurine synthesizing enzymes (CSAD), taurine-specific receptor, and a taurine transporter system.
CSAD = Cysteine sulfinic acid decarboxylase
Taurine as a neuroprotective agent.
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Roles of Taurine in Cardiovascular System
Taurine acts as positive inotropes by promoting calcium-ion release from sarcoplasmic reticulum in cardiac myocytes by modulates calcium transportation during the excitation-contraction coupling.
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Roles of Taurine in Cardiovascular System
Excitation-contraction coupling
of cardiac myocyte.
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Roles of Taurine in Visual System
• Taurine is found in high concentration at the retina, particularly in photoreceptor cell bodies of outer nuclear layer.
• Kittens are more prone to taurine depletion in photoreceptor cells compared to adult cats.
Photoreceptor cell
Phototransductionsystem
oute
r seg
men
tIn
ner s
egm
ent
Synaptic terminal
CNG channel
Na+/Ca2+
exchangerdisks
Ca2+
Na+
Ca2+
Na+
taurinedepolarization
Intracellular Ca2+
reopening
Ca2+Na+
Outer segment
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Roles of Taurine in Immune System
Myeloperoxidase
Taurine can eradicate free radicals generated from specific myeloperoxidase reaction, i.e. hypochlorous acid (HOCl) and hypobromous acid (HOBr), thus it can reduce oxidative stress.
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Roles of Taurine in Renal SystemRenal vascular
resistance
• Taurine aids in renal blood flow regulation.
Glomerulus
• Elimination of reactive oxygen species (ROS)
Proximal tubule
•Taurine affects sodium transportation.•Regulation of taurine body pool size.
Medullary collecting duct
• Taurine acts as osmoregulator, thus it can control the cell volume.
Taurine may prevent glomerulonephritis, diabetic nephopathy, chronic renal failure, and acute kidney injury (AKI)
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Roles of Taurine in Renal System
Taurine transport in renal tubular cell
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Taurine Deficiency in Cats
Why are cats more likely to develop taurine deficiency?
-CSAD-Bile conjugation
How does taurine deficiency affects cats health?
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Bile acid conjugationCholestero
l7αHydroxyCholest
erol
Cholic acid(primary bile
acid)
Chenodeoxy(primary bile
acid)
Glyconolic acid
Taurocholic acid
Taurochenodeoxycholic acid
Linthocolic acid(secondary bile
acid)
7αHydroxylase
Taurine TaurineGlycine
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Cardiac
Function
Visual
System
Immune
System
Reproductive
System & Developm
ent
Taurine Deficiency on Cats Health
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Cardiac FunctionDecreas
e Ca2+ influx
Impaired sensitivity of contractile
protein to Ca2+
CellApoptosis
Impaired systole and diastole
Feline Dilated Cardiomyopathy (DCM)
Heart failure
Feline central retinal
degeneration(FCRD)
Tapetum Lucidum
Lateral geniculate body
Superior colliculus
Lens
Retina
Visual system
Feline central retinal degeneration (FCRD)
Tapetum lucidumNORMAL
TAURINE DEFICIENCY
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Immune system
1. Leucopenia
2. Decrease respiratory burst of neutrophils
3. Decrease phagocytic activity of phagocytes
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Reproductive System & Development
Taurine-deficient pregnant queen
1. More incidences of fetal death (resorption), abortion, or stillbirth.
2. Reduction of taurine concentration in feline maternal milk.
Kittens born from taurine-deficient
female cats
1. Low survival rate
2. Low birth weight
3. Growth retardation
4. Bone malformation
5. Impaired nervous and visual system development.
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Kittens born from taurine-deficient female cats.
a. A premature kitten with congenital hydrocephalus.
b. A stillbirth kitten with anencephaly.
c. Severe congenital hydrocephalus, a brain from 1-year old kitten.
a b c
Nutritional Aspects
Commercial diets
Dry dietCanned diet
Recommended amount
Bioavailability
Ingredients
Effects on digestive
physiology
Processing
Taurine Requirement for Cats
Growth and Reproduction
Adult Maintenance
Nutrient Minimum Minimum Maximum
Taurine (extrude,%)
0.10 0.10
Taurine (canned,%)
0.20 0.20
The Association of American Feed Control Officials (AAFCO)
How to prevent taurine deficiency
in cats?
Nutritional Aspects
Commercial diets
Homemade meal
Taurine amount labelled on Hill’s commercial cats
diets
Canned diets (Fed)
Canned diets (DM)
Dry diets (Fed)
Dry diets (DM)
0 0.1 0.2 0.3 0.4 0.5
Dry diet
Canned diet
Recommended taurine
amount
Beef Lamb Pork ChickenCod fish Oyster Clam0
500
1000
1500
2000
2500
3000
Raw Baked
Boiled
Taurine amount in food (mg/kg, wet weight)
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Case studyFeline Dilated Cardiomyopathy
History taking
Domestic male cat, 4 years old, 3.8 kg. body weight
• Signs of depression, poor appetite, cough, and dyspnea since 3 weeks ago.
• The cat has muffled cardiac sound.
• The owner had fed the cat with commercial dog food for 1 year and 6 months.
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Examination
• Thoracic radiograph shows severe fluid accumulation in pleural space.
• Electrocardiography shows decrease in 'R' wave amplitude
• Echocardiography shows incress in EDV = End diastolic volume or LVIDd ↓ , ESV = End systolic volume or LVIDs ↓ and shortening fraction ↑
• Hematology and Serum biochemical parameter are normal
• Direct opthalmoscopic is normal
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Shortening fraction
Measurement Normal
LVIDd (cm) 2.45 1.59 ± 0.19
LVISd (cm) 2.27 0.80 ± 0.14
∆ D (%) 8.5 49.8 ± 5.3
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Thank you for your attention