I begin my scientific musings with coffee... a drink that has been my support system and a has made many a dull days bearable... !!! And so i begin my adventures as a skeptic in wonderland with caffeine, the one thing which is an instantaneous mood lifter for millions all over the world...
Coffee and chocolates.... two things which can lift my mood on any day... all one could want at the end of a long hard day is coffee or some yummy chocolate to feel good and rest well... :-)
Both coffee and chocolate, exert their effects through Caffeine, a psychoactive stimulant drug...
Caffeine is found in varying quantities in the leaves, beans and fruit of some plants like that of tea, coffee, kola and cocoa...Caffeine is contained in coffee, tea, soft drinks and chocoloate... all the stuff that one likes !
Well, Why do plants produce caffeine ? Well, in these plants, caffeine acts as a natural pesticide that paralyzes and kills the insects feeding on them. High caffeine levels have also been found in the soil surrounding coffee bean seedlings, suggesting it to be secretory alkaloid which also serves to inhibit the germination of other seeds near coffee seedlings giving them exclusive access to the resources. (A rather smart strategy must say !!)
In humans however, caffeine is a CNS stimulant which temporarily wards of drowsiness and restores alertness. It also has diuretic effects in people who do not have a tolerance for it. Caffeine is used as a component of several 'over the counter analgesics' like aspirin and in appetite suppressants. Caffeine has been shown to result in decreased fatigue and increased attentiveness... Well.. many of us could attest to that alright !!! (I sure can... :))
Caffeine is also used pharmacologically to treat apnoea in premature newborns and is one of the ten most commonly given drugs in neonatal intensive care.
The history of coffee and its use is a rather fascinating story... Caffeine consumption has been reported in humans right since the stone age. While chewing the seeds, bark or leaves of certain plants had the effect of easing fatigue and elevating one's mood, it was later realized that even the decoction produced by steeping the plants in hot water had the same effect. The history of coffee traces back to the ninth century in its native, Ethiopia. Legend attributes its discovery to a goat herder named who apparently observed the goats becoming hyperactive and sleepless in night after grazing of coffee shrubs, Upon trying the berries eaten by the goats the goatherd also experienced the same sleeplessness and thus began the long journey of coffee as it spread from Ethiopia to all over the world today. The earliest literary mention of coffee dates back to the works of a persian physician Al-Razi in the ninth century. The use of coffee is reported to have spread through Yemen to Egypt and further to Europe. Coffee came into its own in the 17th century where it garnered appreciation in Europe as the "arabian wine" in the 17th century. The entry of coffee into Europe is attributed to the Ottoman turks who left large bags of coffee upon their retreat from Vienna after losing a battle for the city. The coffee beans remained a mystery for the Europeans till Franz George Kolschitzky, a pole who had worked for the turks, taught the Viennese how to make coffee. Thus, the first coffee house in the western world opened in Vienna and this heralded the long tradition of coffee appreciation that has enamored the world till date.
The history for the other major source of caffeine, cocoa, is no less interesting. The earliest evidence for cocoa bean use comes from the ancient mayan sites dated to 600 BC. In teh new world, chocolate was consumed as a bitter and spicy drink called xocolatl, seasoned with vanilla, chile pepper and achiote, a far cry from the chocolates of today. It became an important luxury good in the pre-coulmbian mesoamerica due to ts reputation of fighting fatigue (due to its high caffeine and theobromine content) and this led to cocoa beans often being used as currency. Xocolatl entered Europe through the Spaniards and became a popular beverage by the 1700s.
Caffeine however remained a mystery till 1819, when the German chemist Friedrich Ferdinand Runge isolated relatively pure caffeine for the first time. the elucidation of the structure of caffeine fetched a Nobel to its discoverer Hemrann Emil Fischer in 1902.
Caffeine from coffee or other beverages is absorbed by the stomach and the small intestine within 45 minutes of ingestion and then distributed throughout all the tissues of the body. the half life of caffeine in the body varies depending on a number of factors from about 4.9 hours to 11-12 hours in normal individuals. Caffeine is metabolized in the liver by the cytochrome P450 oxidase enzyme system into three metabolic dimethylxanthines, each of which has its own effects on the body ranging from lipolysis, dilation of blood vessels, and relaxation of the smooth muscles of the bronchi. Each of these metabolites is further metabolized and excreted in the urine.
How does Caffeine work ?
Well, it readily cross the blood brain barrier and once in the brain it acts as a non sleective antagonist for the adenosine receptors. Being structurally similar to adenosine, caffeine binds to the adenosine receptors on the surface of the cells without activating them.... (antagonistic action !!)
While, adenosine plays a role in the ATP related energy and metabolic processes in general, it seem to have certain other special functions in the brain. Brain adenosine appears to protect the brain by suppressing neural activity and also by increasing the blood flow through A2A and A2B adenosine receptors located on the vascular smooth muscle. by counteracting adenosine, caffeine reduces the resting cerebral blood flow between 22 and 30%. In addition caffeine also has a generally disinhibitory effect on neural activity which could possibly lead to arousal and alertness which are the common effects of caffeine intake. Some of the secondary effects of caffeine are also possibly caused due to its functions as a competitive non selective phosphodiesterase inhibitor, which of course will ultimately raise intracellular cAMP thereby activating multiple cellular kinases. By allowing cAMP to build up in the cells, caffeine intensifies and prolongs the effects of epinephrine and other such drugs (amphetamine, methamphetamine etc), thereby increasing the heart rate and the general alertness...
As always of course, continued caffeine consumption can have a flip side leading to caffeine tolerance, addiction and withdrawal symptoms. Being an antagonist for adenosine, high caffeine consumption leads to a substantial increase in the number of adenosine receptors in the CNS, ultimately of course leading to increased sensitivity to adenosine. Because adenosine serves to regulate blood pressure by causing vasodilation, the increased effects of adenosine due to caffeine withdrawal cause the blood vessels of the head to dilate leading to excess blood in the head causing head ache and nausea. the effect is further compounded by the absence of the vaso-constrictive effects of caffeine.
The good news however is that, the withdrawal symptoms are all reversible and disppear in roughly one to five days, the time required for the number of adenosine receptors in the brain to come down to "normal levels", uninfluenced by caffeine consumption.
It is quite amazing how much a tiny alkaloid can influence our existence... :)
I have a fair understanding of caffeine and its mode of action but questions remain.... How does the brain return to the normal levels of the adenosine receptor upon discontinuation of caffeine? What is the exact mechanism of action of caffeine and is there a way to remove its withdrawal symptoms ?
As i read all about caffeine and its mode of action, i did realize that moderation is the key... (mind you.... i am no where near the danger line as i only depend on my two cups of strong coffee in a day), but, as i cut down on my coffee consumption, i do hope that i manage to find other non addictive and equally pleasurable ways of staying awake and alert...
Coffee and chocolates.... two things which can lift my mood on any day... all one could want at the end of a long hard day is coffee or some yummy chocolate to feel good and rest well... :-)
Both coffee and chocolate, exert their effects through Caffeine, a psychoactive stimulant drug...
Caffeine is found in varying quantities in the leaves, beans and fruit of some plants like that of tea, coffee, kola and cocoa...Caffeine is contained in coffee, tea, soft drinks and chocoloate... all the stuff that one likes !
Well, Why do plants produce caffeine ? Well, in these plants, caffeine acts as a natural pesticide that paralyzes and kills the insects feeding on them. High caffeine levels have also been found in the soil surrounding coffee bean seedlings, suggesting it to be secretory alkaloid which also serves to inhibit the germination of other seeds near coffee seedlings giving them exclusive access to the resources. (A rather smart strategy must say !!)
In humans however, caffeine is a CNS stimulant which temporarily wards of drowsiness and restores alertness. It also has diuretic effects in people who do not have a tolerance for it. Caffeine is used as a component of several 'over the counter analgesics' like aspirin and in appetite suppressants. Caffeine has been shown to result in decreased fatigue and increased attentiveness... Well.. many of us could attest to that alright !!! (I sure can... :))
Caffeine is also used pharmacologically to treat apnoea in premature newborns and is one of the ten most commonly given drugs in neonatal intensive care.
The history of coffee and its use is a rather fascinating story... Caffeine consumption has been reported in humans right since the stone age. While chewing the seeds, bark or leaves of certain plants had the effect of easing fatigue and elevating one's mood, it was later realized that even the decoction produced by steeping the plants in hot water had the same effect. The history of coffee traces back to the ninth century in its native, Ethiopia. Legend attributes its discovery to a goat herder named who apparently observed the goats becoming hyperactive and sleepless in night after grazing of coffee shrubs, Upon trying the berries eaten by the goats the goatherd also experienced the same sleeplessness and thus began the long journey of coffee as it spread from Ethiopia to all over the world today. The earliest literary mention of coffee dates back to the works of a persian physician Al-Razi in the ninth century. The use of coffee is reported to have spread through Yemen to Egypt and further to Europe. Coffee came into its own in the 17th century where it garnered appreciation in Europe as the "arabian wine" in the 17th century. The entry of coffee into Europe is attributed to the Ottoman turks who left large bags of coffee upon their retreat from Vienna after losing a battle for the city. The coffee beans remained a mystery for the Europeans till Franz George Kolschitzky, a pole who had worked for the turks, taught the Viennese how to make coffee. Thus, the first coffee house in the western world opened in Vienna and this heralded the long tradition of coffee appreciation that has enamored the world till date.
The history for the other major source of caffeine, cocoa, is no less interesting. The earliest evidence for cocoa bean use comes from the ancient mayan sites dated to 600 BC. In teh new world, chocolate was consumed as a bitter and spicy drink called xocolatl, seasoned with vanilla, chile pepper and achiote, a far cry from the chocolates of today. It became an important luxury good in the pre-coulmbian mesoamerica due to ts reputation of fighting fatigue (due to its high caffeine and theobromine content) and this led to cocoa beans often being used as currency. Xocolatl entered Europe through the Spaniards and became a popular beverage by the 1700s.
Caffeine however remained a mystery till 1819, when the German chemist Friedrich Ferdinand Runge isolated relatively pure caffeine for the first time. the elucidation of the structure of caffeine fetched a Nobel to its discoverer Hemrann Emil Fischer in 1902.
Caffeine from coffee or other beverages is absorbed by the stomach and the small intestine within 45 minutes of ingestion and then distributed throughout all the tissues of the body. the half life of caffeine in the body varies depending on a number of factors from about 4.9 hours to 11-12 hours in normal individuals. Caffeine is metabolized in the liver by the cytochrome P450 oxidase enzyme system into three metabolic dimethylxanthines, each of which has its own effects on the body ranging from lipolysis, dilation of blood vessels, and relaxation of the smooth muscles of the bronchi. Each of these metabolites is further metabolized and excreted in the urine.
How does Caffeine work ?
Well, it readily cross the blood brain barrier and once in the brain it acts as a non sleective antagonist for the adenosine receptors. Being structurally similar to adenosine, caffeine binds to the adenosine receptors on the surface of the cells without activating them.... (antagonistic action !!)
While, adenosine plays a role in the ATP related energy and metabolic processes in general, it seem to have certain other special functions in the brain. Brain adenosine appears to protect the brain by suppressing neural activity and also by increasing the blood flow through A2A and A2B adenosine receptors located on the vascular smooth muscle. by counteracting adenosine, caffeine reduces the resting cerebral blood flow between 22 and 30%. In addition caffeine also has a generally disinhibitory effect on neural activity which could possibly lead to arousal and alertness which are the common effects of caffeine intake. Some of the secondary effects of caffeine are also possibly caused due to its functions as a competitive non selective phosphodiesterase inhibitor, which of course will ultimately raise intracellular cAMP thereby activating multiple cellular kinases. By allowing cAMP to build up in the cells, caffeine intensifies and prolongs the effects of epinephrine and other such drugs (amphetamine, methamphetamine etc), thereby increasing the heart rate and the general alertness...
As always of course, continued caffeine consumption can have a flip side leading to caffeine tolerance, addiction and withdrawal symptoms. Being an antagonist for adenosine, high caffeine consumption leads to a substantial increase in the number of adenosine receptors in the CNS, ultimately of course leading to increased sensitivity to adenosine. Because adenosine serves to regulate blood pressure by causing vasodilation, the increased effects of adenosine due to caffeine withdrawal cause the blood vessels of the head to dilate leading to excess blood in the head causing head ache and nausea. the effect is further compounded by the absence of the vaso-constrictive effects of caffeine.
The good news however is that, the withdrawal symptoms are all reversible and disppear in roughly one to five days, the time required for the number of adenosine receptors in the brain to come down to "normal levels", uninfluenced by caffeine consumption.
It is quite amazing how much a tiny alkaloid can influence our existence... :)
I have a fair understanding of caffeine and its mode of action but questions remain.... How does the brain return to the normal levels of the adenosine receptor upon discontinuation of caffeine? What is the exact mechanism of action of caffeine and is there a way to remove its withdrawal symptoms ?
As i read all about caffeine and its mode of action, i did realize that moderation is the key... (mind you.... i am no where near the danger line as i only depend on my two cups of strong coffee in a day), but, as i cut down on my coffee consumption, i do hope that i manage to find other non addictive and equally pleasurable ways of staying awake and alert...
