Transcript Taurine Deficiency in Cats

A Seminar on
Taurine Deficiency in Cats
Group 10
1
March 3, 2014
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.
2
Biosynthesis of Taurine
Methionine
Vit
Transulfuration
Cystein
Phosphopantothenate
Cysteine
dioxygenase (CDO)
Cysteine
sulfunic acid
Cysteine sulfinic acid
dehydrogenase
Cysteamine
Cysteamine
dioxygenase
Hypotaurine
Hypotaurine
decarboxylase
Taurine
Cysteic acid
3
A dietary deficiency of vitamin B6 shows a depressing effect on
taurine biosynthesis.
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
4
Physiological Function of Taurine
Bile acid
conjugation
Nervous
Cardiovascular
system
system
Taurine
Renal
system
Visual
system
Immune
system
5
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
6
Taurine as a neuroprotective agent.
7
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 excitationcontraction coupling.
8
Roles of Taurine in
Cardiovascular System
Excitation-contraction coupling
9
of cardiac myocyte.
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.
10
Synaptic
terminal
Inner segment
outer segment
Outer segment
Na+/Ca2+
exchanger
disks
CNG
channelNa+
Ca2+
Ca2+
Na+
Ca2+
Na+
reopening
depolarization
Intracellular Ca2+
taurine
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.
13
Roles of Taurine in Renal
System
Renal vascular
resistance
• Taurine aids
in
renal
blood flow
regulation.
Glomerulus
• Elimination
of reactive
oxygen
species
(ROS)
Proximal
tubule
Medullary
collecting duct
• Taurine affects
sodium
transportation.
• Regulation of
taurine body
pool size.
• 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)
14
Roles of Taurine in Renal
System
Taurine transport in renal tubular cell
15
Taurine Deficiency in Cats
Why are cats more likely to develop taurine deficiency?
-CSAD
-Bile conjugation
How does taurine deficiency affects
cats health?
16
Bile acid conjugation
Cholesterol
7αHydroxylase
7αHydroxyCholesterol
Cholic acid
(primary bile acid)
Glycine
Glyconolic
acid
Taurine
Taurocholic
acid
Chenodeoxy
(primary bile acid)
Taurine
Taurochenodeoxycholic acid
Linthocolic acid
17
(secondary bile acid)
Taurine Deficiency on Cats
Health
Immune
System
Visual
System
Reproductive
System &
Development
Cardiac
Function
18
Cardiac Function
Impaired sensitivity
of contractile protein
to Ca2+
Decrease
Ca2+ influx
Cell
Apoptosis
Impaired systole and diastole
Feline Dilated Cardiomyopathy (DCM)
Heart failure
19
Immune system
1. Leucopenia
2. Decrease respiratory burst of
neutrophils
3. Decrease phagocytic activity of
phagocytes
23
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 taurinedeficient female cats
1.
2.
3.
4.
5.
Low survival rate
Low birth weight
Growth retardation
Bone malformation
Impaired nervous and
visual
system
development.
24
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.
25
Nutritional
Aspects
Recommended amount
Commercial
diets
Bioavailability
Ingredients Processing
Effects on digestive
physiology
26
Taurine Requirement for Cats
The Association of American Feed Control Officials
(AAFCO)
Growth and
Reproduction
Adult Maintenance
Nutrient
Minimum
Minimum
Taurine
(extrude,%)
Taurine
(canned,%)
0.10
0.10
0.20
0.20
Maximum
27
Nutritional
Aspects
How to prevent taurine
deficiency in cats?
Commercial
diets
Homemade
meal
28
Taurine amount labelled on Hill’s
commercial cats diets
Dry diets (DM)
Dry diet
Canned diet
Dry diets (Fed)
Canned diets (DM)
Canned diets (Fed)
29
0
0.1
0.2
0.3
0.4
0.5
Taurine amount in food
(mg/kg, wet weight)
3000
2500
Raw
2000
Baked
Boiled
1500
1000
500
30
0
Beef
Lamb
Pork
Chicken Cod fish Oyster
Clam
Case study
Feline 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.
31
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
32
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
33
Thank you for your attention
34