I was recently asked over on twitter(@ciltep) if I thought caffeine was an essential part of the stack. I've been consuming caffeine in one form or another every day for many years so it's a bit of a confound as to whether it is required. At least for me, it certainly doesn't hurt the effect too much.
There's evidence that caffeine increases levels of phosphorylated CREB, which is an important transcription factor for LTP.
http://www.ncbi.nlm....pubmed/21907331Caffeine treatment stimulated PKA activity, increased phospho-CREB levels, and decreased phospho-JNK and phospho-ERK expression in the striatum of APPswe mice, all of which are thought to be beneficial changes for brain function. Even caffeine-treated NT mice exhibited some of these changes in striatum. In the frontal cortex, caffeine did not significantly increase phospho-CREB and PKA activity, but significantly reduced phospho-JNK and phospho-ERK expression in both APPswe and NT mice.
However, here's another study that says that Caffeine actually
inhibits cAMP increase by forskolin.
http://www.ncbi.nlm..../pubmed/1309235Forskolin stimulation of cyclic AMP accumulation in rat brain cortex slices is markedly enhanced by endogenous adenosine.
DeLapp NW, Eckols K.
Source
CNS/GU/GI Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, Indiana 46285.
Abstract
Stimulation of cyclic AMP (cAMP) accumulation in rat cortex slices by 1 microM forskolin (F) was markedly reduced (96%) by treatment with adenosine deaminase (ADA). The effect of ADA was progressively less at higher concentrations of F, but still inhibited the response by 50% at 100 microM F. ADA-mediated inhibition of the cAMP response to 1 microM F was completely reversed by 5 microM 2-chloroadenosine (CA), an ADA-resistant analogue. Stimulation by F (controls) and F plus CA (ADA treated) in cortex slices was significantly inhibited by 200 microM caffeine (CAF) and by 10 microM 8-phenyltheophylline. cAMP accumulation in ADA-treated cortex slices stimulated with CA at concentrations from 5 to 100 microM was markedly enhanced by 1 microM F. Neither ADA treatment nor 200 microM CAF significantly affected cAMP accumulation in slices stimulated by 1 microM vasoactive intestinal polypeptide or adenylate cyclase in membranes stimulated by 1 microM F. CAF (1 mM) did not significantly increase basal cAMP levels in cortex slices, whereas 1 mM 3-isobutyl-1-methylxanthine caused a significant 80% increase and 100 microM rolipram enhanced cAMP levels by 4.5-fold. F-stimulated cAMP accumulation (1 microM) in cortex slices was inhibited 98% by 1 mM CAF and 49% by 1 mM 3-isobutyl-1-methylxanthine, and was enhanced 2.5-fold by 100 microM rolipram. These data have been interpreted to indicate that the stimulation of cAMP accumulation in rat cortex slices by 1 microM F is predominantly due to synergistic interaction with endogenous adenosine and that the inhibition of this response by CAF is largely due to blockade of adenosine receptors.
Wow. This is pretty surprising!
Is anyone taking the stack *without* caffeine?
Here's a study that says that caffeine increases cAMP via blocking adenosine's activity on GTP-binding Protein:
http://www.ncbi.nlm..../pubmed/1888264Biochemical mechanism of caffeine tolerance.
Ammon HP.
Source
Department of Pharmacology, University of Tübingen, FRG.
Abstract
Most of the biological actions of caffeine are possibly mediated through its antagonistic effects toadenosine. Adenosine activates an inhibitory GTP-binding protein (Gi). One of the physiological actions of Gi is the inhibition of cAMP formation. Caffeine overcomes this action thus leading to elevation of cAMP. Firing of neurons and the release of neurotransmitters is also inhibited byadenosine. Caffeine overcomes this effect, thus producing increased CNS-activity. During long term administration of caffeine many functions of the organism develop tolerance including cardiovascular and central nervous systems. Present evidence suggests that caffeine tolerancefollowing continuous severe coffee ingestion is the response of the body against caffeine through the upregulation of adenosine receptors.
So caffeine and forskolin both raise cAMP but caffeine cancels forskolin's effects.
I have seen references to caffeine being a PDE inhibitor in the literature. I found the study that contains this finding:
http://www.ncbi.nlm....pubmed/10049999FullText:
http://pharmrev.aspe...nt/51/1/83.longActions of caffeine in the brain with special reference to factors that contribute to its widespread use.
Nice chart from that study:
cafchart.jpg 119.28KB
22 downloadsAccording to the chart, caffeine,
at normal doses, is not a significant PDE inhibitor. it should go without saying, but please do not take high doses of caffeine as it's dangerous.
So theoretical evidence says caffeine is probably not required. Caffeine, at some dosage, may also prevent Forskolin from working. However, in my direct experience, caffeine, at levels usually between 200-400mg, does not prevent the stack from working.
Edited by abelard lindsay, 04 August 2013 - 09:44 AM.