What is The
thrifty phenotype hypothesis in
obesity?????, Forget about
China Virus:: ABC of Obesity
::-People from the Indian subcontinent
are highly prone to central
obesity and diabetes
either within those
countries of the subcontinent or after migration to the United Kingdom but recent evidence
suggests that not all groups of
people are equally vulnerable. According
to the general thrust of the thrifty phenotype
hypothesis, the most important
measure for determining risk of
metabolic syndrome should be the
speed of transition from a life of
thrift to a life of plenty . However this part of the hypothesis does not always
hold true. It is not true for example
in the case of Tibetans who have
migrated to India. Coming from a life
of thrift environment in Tibet to a more life of plenty environment in India,
the Tibetans in India would according to the thrifty phenotype hypothesis be expected to be
more prone to diabetes than peninsular
Indians.
What
about Tibetans??
That is not the case however Tibetans who have migrated to India are less
prone to diabetes that peninsular Indians. Similarly Japanese who migrate to Hawaii and Los Angeles might be expected to be more prone to diabetes than people who have lived in Hawaii or Los Angeles for generations. Data show otherwise however Japanese migrants
to those two places are less
prone to obesity and diabetes than the
established populations. These
observations have led to the
hypothesis that another key factor in determining risk is climate
. CAN it be explained
by gene environment interactions ? It is
now widely accepted that genetic
and epigenetic pathways mediate much of the relationship between the
environment and eh developmental origins of health and disease
paradigm. Sequence variation within the genetic modification of the genome which can influence
an individual’s risk of health and disease . Both
mechanisms likely
contribute to the variation seen in an individual’s response to the environment though
their relative
contributions and the extent
of interactions between the pathways
remain to be determined.
Where is your
birth place ??This is not related to NCA??? But to obesity. Believe me obesity is related
to your ancestors living place!!!! Where your ancestors lived??? Risk may be lower for
groups whose ancestors lived in
cold hares climates. In an environment
in which agriculture and hunting is
not possible for much of the year reliance on limited
quantities of stored food may be expected to result in insulin resistance. The
principles that underpin the thrifty phenotype hypothesis
would suggest that such descendents
would be more at risk of diabetes, rather than less. This leads to the possibility that different groups of people may have different
genetic predispositions to obesity
and diabetes.
Fat, Fat, Fat –fat is discussed everywhere-In all
conferences /CME/ Seminars everywhere :
But who will discuss and talk about free Fatty acids??? Effects of gender and obesity
on fatty acid and triglyceride metabolism in the post absorptive state
Ans
& explanation on Free fatty acids :-Circulating FFAs which are mainly derived from the breakdown of
endogenous triglyceride stored in adipose
tissue are an important
sourced of fuel. FFA release
from adipose tissue is well regulated by the coordinated action of many endocrine paracrine and other
factors, allowing appropriate availability of FFA to meet
the energy requirements of tissues., which is thought to be responsible
for many of the metabolic
abnormalities associated with obesity including hypertriglyceridaemia and insulin resistance.
In the post absorptive state the rate
of FFA release into the circulation
at the whole body level is not different
between men and women matched for body mass index
level is not different between
men and women matched for body mass
index whether lean or obese . However this comparison although often made does not take into account differences in
body size between men and women . In fact FFA
release relative to lean
mass an
index of FFA released into plasma in relationship to the tissues that consume FFA for use as a fuel is greater in women than men whereas FFA release
relative to the size of
adipose tissue - an
index of FFA released into plasma
with respect to the recently found that the differences in FFA release between
men and women present in lean overweight and obese individuals and are
largely a result of
differences in Ra increased
linearly with increasing fat mass and there were no differences between men and women in the relationship
between fat mass and total FFA Ra.
Consequently FFA Ra in relationship to fat free mass is grater in obese than lean
subjects and greater in women
than in men . Very similar
observations have been made for FFA Ra
in relation to resulting energy
expenditure most likely because of the
close relationship between resulting energy
expenditure and fat free mass.
Despite the considerable
lipolytic heterogeneity between different adipose
tissue regions FFA release from upper
body patterns of fat storage in
the body between genders, there are no
major differences upper body nonsplanchnic subcutaneous adipose tissue beds to whole
body FFA Ra. Increased release of FFA in obese compared with lean subjects is predominantly because
of increased FFA release rates
from splanchnic and lower body adipose tissues but not from
upper body non splanchnic
adipose tissue.
In summary
FFA release into plasma appears to be tightly associated with energy
requirements of lean tissues however
for any given amount of fat free tissues or energy expenditure
plasma FFA availability is greater in women than in men and in obese
than lean subjects because
women and obese subjects have more
body fat than men and lean subjects
respectively.
The majority
of plasma triglyceride in the
fasting state circulates
in the core of VLDLs, which are
produced and secreted
by the liver thereby
providing energy dense
substrates to peripheral tissue while
at the same time buffering excess
amounts of plasma FFA that would
otherwise be cytotoxic. VLDL is assembled in hepatocytes in a two step process that involves the partial lipidation of a newly
synthesized apoB- 100 , which is an
essential structural component and does
not participate in the subsequent intravascular remodeling
of the lipoprotein particle
whereas the availability of core
triglyceride varies considerably and determines the size and possibly also the metabolic fate of VLDL . Fatty acids used for hepatic triglyceride synthesis originate
primarily from th systemic
plasma FFA pool as well as from
several other non systemic
fatty acid sources such as
hepatic de novo lipgenesis , and lipolysis of intrahepatic and
visceral at triglyceride.
Dysregulation of VLDL metabolism can lead
to increased plasma VLDL
triglyceride concentration greater number of circulating VLDL
particles and large
triglyceride rich VLDL all of
which are associated with increased risk for
cardiovascular disease.
I am ignorant
about female psychology, love and their affinity, dependency, more bondage
& affection to HPO axis !!!! Effects of female obesity on the endocrinology
and function of the hypothalamic pituitary
ovarian axis. Please don’t ask me how & why F gonad and different systems
are much governed by HP axis. I am governed by good foods only!!!!
The association between
obesity and infertility is partially
related to oligo ovulation or anovulation PCOS
is commonly associated with
ovulatory dysfunction
hyperandrogenemia and PCOS appearing
ovaries on ultrasound and frequently is associated with BMI
values greater than 25 kg/ m . In addition obese
PCOS women have higher rates of anovulation than leaner
patients who have the same
diagnosis and the response and doses
used for induction of ovulation
also are higher with suboptimal
ovulatory responses. An additional
barrier to adequate response
to ovulation induction
medications is the
hyperinsulinemia and insulin resistance
associated with the increase in fat
in particular the
abdominal phenotype of obesity which defines it as a condition of relative
functional hyperandrogenism . Adipose
tissue also is able to store lipid soluble steroids including androgens which seem
preferentially concentrated within
the adipose tissue rather than in the blood. Therefore because
there is more abundant fat tissue rather than
blood in obese patients
steroid concentrations are greater than in normal weight individuals. Furthermore fat represents a site of intense sex hormone
metabolism resulting from
steroidogenic enzymes such as
3B dehydrogenase 17 B hydroxydehydrogenase and aromatase. Estradiol levels from
increased peripheral aromatization of androgens also have a direct negative effect on
the hypothalamus modifying
GnRH pulsatility and reducing
gonadotropins at the pituitary . The subsequent relative
hypogonadotropic
environment result in anovulation .
Insulin
has a negative effect on the synthesis of SHBG
by the liver truncal obesity is
associated with insulin resistance and increases in free testosterone and dihydrotestosterone. Levels of SHBG
air regulated by other complex
factors including estrogens iodo thyronines and growth hormone as stimulating agents
and androgens and insulin as
inhibiting factors. Insulin binds with low
affinity to the LH receptor in the
theca cell and hyperinsulinemia
may stimulate compensatory
ovarian theca cell steroidogenesis and androgen production
via the saturation of the receptor
which may inhibit normal ovulation via premature follicular
atresia and premature luteinization .
Part of the new Rotterdam criteria for the diagnosis of PCOS
includes the ultrasound appearance
of PCOS appearing ovaries where abundant follicles at the antral
stage in the ovarian a cortex are
responsible for this endocrine milieu.
Follicular development may be affected by increased reactive oxygen
species. In addition leptin a
surrogate marker for fat mass can directly modulate granulosa
theca and interstitial cells with inhibition
jof steroidogenesis and oocyte
maturation thereby providing
an additional potential mechanism
for anovulation .
What is The
endocannaboid system???? The endocannaboid system also plays a pivotal role in the anovulation of obesity
. Its primary negative effect is in the hypothalamus although some
down regulating influences may be
mediated directly at the
level of the pituitary and ovary
. By suppressing the secretory pulsatility of LH
endocannabinoids can down
regulate serum LH levels but
administration of
gonadotropins of pulsatile GnRH can restore ovulation and LH
release. These effects are mediated by neurotransmitters known to facilitate GnRH secretion such as norepinephrine and glutamate and by stimulating those modulators known
to down regulate GnRH
secretion such as dopamine Y
aminobutyric acid opioids and
corticotrophin releasing hormone.
All right .You
are like me. Sleep up to 09 00 hrs. !! That’s fine. U are also like me weighing 130 kg only!!! No problem. Mai hu
na!!! What are then the most commonly
used Anti Obesity Drug ??
Orlistat is
the drug I am ingesting from the age of six months!!! .Because it acts as Lipase inhibitor
by which it exerts anti obesity Action
: The Indications & Doses :
Obesity : orally :for adults like me 120 mg TID
with each main meal containing
fat and it includes for weight loss & management when used in conjunction with
a reduced calorie & low fat
diet.
Drug safety : Hypersensitivity chronic malabsorption syndrome / cholestasis [ S/p : history of hyperoxaluria /Ca
oxalate nephrolithiasis type ll
DM] ADR: Serious : HTN others : GI
disturbances fecal urgency & incontinence
, flatulence , fatty stools /
discharge , anxiety fatigue
menstrual irregularities , increased
risk of breast cancer, headache [ DDl ;Vit E/ Amiodarone
absorption reduced : Coumarins
absorption reduced that leads to increase in INR , ACEls increase
in BP . Hormonal contraceptives
risk of contraceptive failure
is increased [ Monitor
BMI , diet (calorie & fat
intake ) serum glucose , TFT , LFTs.
No comments:
Post a Comment