Blood Pressure Effects of Dietary Caffeine Are a Risk for Cardiovascular Disease
Barry D. Smith, Uma Gupta, B.S. Gupta in Caffeine and Activation Theory, 2006
Adenosine is a neuromodulator that acts upon specific cell-surface receptors distributed throughout the body, including the central nervous system and the cardiovascular system. Having a similar molecular structure to adenosine, caffeine occupies adenosine receptor sites, thereby antagonizing the normal physiological actions of adenosine. The fact that adenosine has an important role in the regulation of cardiovascular function provides biological plausibility to the hypothesis that caffeine is a cardiovascular risk factor. Thus, taking account of these various facts about caffeine (i.e., high prevalence of use, life-long exposure for most consumers, high prevalence of cardiovascular disease, and high plausibility regarding suspected biological mechanisms of action), interest in dietary caffeine as a possible cause of cardiovascular disease is well justified.
Pharmacotherapy of Neurochemical Imbalances
Sahab Uddin, Rashid Mamunur in Advances in Neuropharmacology, 2020
Adenosine is produced intracellularly from ATP. It is not packaged into vesicles but is released mainly by carrier mediated transport. Because the intracellular concentration of ATP greatly exceeds that of adenosine, conversion of a small proportion of ATP results in a large increase in adenosine. ATP is stored into vesicles and released by exocytosis as a conventional transmitter, but can also leak out of cells in large amounts under conditions of tissue damage. Like glutamate, ATP can behave as an excitotoxin in high concentrations leading to neuronal damage. However, it is rapidly converted back to adenosine exerting protective effect. This neuroprotective characteristic of adenosine proposes that it can be used as a security tool keeping the neurons safe from damage in conditions like ischaemia or seizure activity in which their viability is at risk (Edward and Gibb, 1992).
Biological Basis of Behavior
Mohamed Ahmed Abd El-Hay in Understanding Psychology for Medicine and Nursing, 2019
Some neurotransmitters, such as acetylcholine and dopamine, can have both excitatory and inhibitory effects depending upon the type of receptors that are present. Neurotransmitters can be categorized as one of six types:Acetylcholine.Biogenic amines (monoamines): catecholamines (dopamine, norepinephrine), serotonin, and histamine.Amino acids: gamma-aminobutyric acid (GABA), glycine, glutamate, and aspartate.Neuropeptides: oxytocin, endorphins, vasopressin, etc.Purines: adenosine, ATP.Lipids and gases: nitric oxide, cannabinoids.
Current and new pharmacotherapeutic approaches for glaucoma
Published in Expert Opinion on Pharmacotherapy, 2020
Wesam Shamseldin Shalaby, Vikram Shankar, Reza Razeghinejad, L. Jay Katz
Adenosine is a naturally occurring purine nucleoside that modulates many physiologic processes. Cellular signaling by adenosine occurs through four known adenosine receptor subtypes (A1, A2A, A2B, and A3). Adenosine and its receptors play a complex role in IOP modulation. Selective A1 receptor agonism has been demonstrated to lower IOP in animal models [108,109], while agonism of non-A1 receptors can elevate IOP [110]. Trabodenoson or INO-8875 (Inotek Pharmaceuticals Corporation, Lexington, MA, USA) is an adenosine mimetic that has a high affinity and specificity for the adenosine A1 receptor. The IOP-lowering effect of trabodenoson has been suggested to be via increasing conventional outflow by increasing the secretion of matrix metalloproteinase-2, which digests collagen type IV, a major component of extracellular matrix in the trabecular meshwork [111]. Although the results of phase I and II clinical trials were promising regarding safety and efficacy [112,113], the drug failed to reach the primary endpoint in the first phase III trial (MATrX-1) of superiority in IOP reduction compared to placebo at all 12 time points [114]. The same happened in phase II clinical trial evaluating the efficacy of fixed formulation of trabodenoson and latanoprost, as the results showed no meaningful clinical advantage over latanoprost alone [115].
Shaddock (Citrus maxima) peels extract restores cognitive function, cholinergic and purinergic enzyme systems in scopolamine-induced amnesic rats
Published in Drug and Chemical Toxicology, 2022
Ayokunle O. Ademosun, Adeniyi A. Adebayo, Temitope V. Popoola, Ganiyu Oboh
Purinergic signaling influences the proper functioning of the nervous system, it is important in the perfection of functional activity between neurons, glial cells, and vascular cells in the CNS (Maria et al.2009). The decrease in these extracellular signaling molecules by an increase in ATPdase and ADA results in cognitive dysfunction. ATPdase activity in scopolamine-induced cognitive dysfunction rats is observed to be higher compared to the control and other groups. ATPdase catalyzes the breakdown of ATP into ADP, scopolamine increases the activity of this enzyme in the hippocampus of rat’s brain thereby decreasing the level of ATP this can result in loss of information in the brain: ATP is converted to cAMP by adenosine cyclase. cAMP is a second messenger that directly or indirectly affects information circulation within a system. An increase in ATPdase leads to a reduced level of cAMP and loss of information, eventually leading to cognitive dysfunction. Adenosine in the brain plays an important neuromodulatory role in the CNS in mammals.
Phenolic Constituents and Inhibitory Effects of Hibiscus sabdariffa L. (Sorrel) Calyx on Cholinergic, Monoaminergic, and Purinergic Enzyme Activities
Published in Journal of Dietary Supplements, 2018
Ganiyu Oboh, Taiwo M. Adewuni, Adedayo O. Ademiluyi, Tosin A. Olasehinde, Ayokunle O. Ademosun
Overexpression of ecto-5′ nucleotidase (E-NTDase) has been reported in some neurodegenerative conditions associated with neuroinflammation and neuroimmune reactions (Burnstock, 2008). Ecto-5′ nucleotidase plays an important role in purinergic transmission and nucleotide-mediated signaling via the regulation of the hydrolysis of adenosine monophosphate to adenosine and inorganic phosphate. Alteration in E-NTDase activity can increase levels of adenosine in the synaptic cleft, which may in turn disrupt the release of other neurotransmitters such as ACh, dopamine, glutamate, epinephrine, and noradrenaline. Our results demonstrate that sorrel extract reduced the activity of E-NTDase activity in rat brain. The ability of sorrel extract to reduce E-NTDase activity will cause adenosine to be available at the synaptic cleft at physiological levels. Adenosine is a neuromodulator and has been reported to play an important role in protecting the brain against neuronal dysfunction. The inhibitory effects displayed by the extracts could be linked to the phenolic constituents. Rutin, kaempferol, quercetin, and chlorogenic and caffeic acids have been reported to contribute to the inhibition of E-NTDase activity (Boligon et al., 2015). However, the molecular basis for the inhibition of the enzyme is not well elucidated.
Related Knowledge Centers
- Adenine
- Cyclic Adenosine Monophosphate
- DNA
- Glycosidic Bond
- Nucleoside
- Organic Compound
- Rna
- Signal Transduction
- Deoxyadenosine
- Adenosine Triphosphate