Theobromine Improves Working Memory by Activating the CaMKII/CREB/BDNF Pathway in Rats

Abstract

Theobromine (TB) is a primary methylxanthine found in cacao beans. cAMP-response element-binding protein (CREB) is a transcription factor, which is involved in different brain processes that bring about cellular changes in response to discrete sets of instructions, including the induction of brain-derived neurotropic factor (BDNF). Ca2+/calmodulin-dependent protein kinase II (CaMKII) has been strongly implicated in the memory formation of different species as a key regulator of gene expression. Here we investigated whether TB acts on the CaMKII/CREB/BDNF pathway in a way that might improve the cognitive and learning function in rats. Male Wistar rats (5 weeks old) were divided into two groups. For 73 days, the control rats (CN rats) were fed a normal diet, while the TB-fed rats (TB rats) received the same food, but with a 0.05% TB supplement. To assess the effects of TB on cognitive and learning ability in rats: The radial arm maze task, novel object recognition test, and Y-maze test were used. Then, the brain was removed and the medial prefrontal cortex (mPFC) was isolated for Western Blot, real-time PCR and enzyme-linked immunosorbent assay. Phosphorylated CaMKII (p-CaMKII), phosphorylated CREB (p-CREB), and BDNF level in the mPFC were measured. In all the behavior tests, working memory seemed to be improved by TB ingestion. In addition, p-CaMKII and p-CREB levels were significantly elevated in the mPFC of TB rats in comparison to those of CN rats. We also found that cortical BDNF protein and mRNA levels in TB rats were significantly greater than those in CN rats. These results suggest that orally supplemented TB upregulates the CaMKII/CREB/BDNF pathway in the mPFC, which may then improve working memory in rats.

Salivary Immunoglobulin A Secretion and Polymeric Ig Receptor Expression in the Submandibular Glands Are Enhanced in Heat-Acclimated Rats

“…After blood collection, 0.5 mL of blood sample was immediately used for blood cell counts. The following variables were measured in the CN and HE groups using a KX-21NV automatic hemocytometer (Sysmex, Kobe, Japan) as described previously [52,54]: WBC, RBC, PLT, HGB, HTC, MCH, MCHC and MCV. After blood cell counts, approximately 3.5 ml of blood was centrifuged (1500× g) for 20 min at 4 • C. Plasma was collected, flash frozen in liquid nitrogen and stored at −80 • C until use.…”

“…Absorbance was measured using a DTX880 multi-mode microplate reader (Beckman Coulter, Pasadena, CA, USA). IgA, GC and HSP70 concentrations were calculated using SoftMax pro software (Molecular Devices, LLC, San Jose, CA, USA) as described previously [54,55]. The IgA flow rate in saliva (µg/min/g SMG tissue) was calculated by multiplying the absolute concentration of IgA (µg/mL) by the saliva flow rate (mL/min) as per g of SMG tissue.…”

Sub-Chronic Consumption of Dark Chocolate Enhances Cognitive Function and Releases Nerve Growth Factors: A Parallel-Group Randomized Trial

“…However, neither can we confirm that dark chocolate-mediated cognitive enhancements are unrelated to NGF and BDNF levels in the human brain, since we are not able to determine the levels of NGF and BDNF in the human brain following dark chocolate intake. However, theobromine—which dark chocolate is rich in—was found to increase the level of BDNF in mouse and rat brains [14,19], implying that dark chocolate may upregulate NGF and/or BDNF in the human brain and improve cognitive function.…”

“…An increase in intracellular cAMP level activates the cAMP-response element-binding protein (CREB), which in turn, leads to the expression of the brain-derived neurotrophic factor (BDNF), one of the neurotrophins that mediates neuronal functions such as learning and memory. We also recently showed that theobromine-fed mice and rats performed better in memory tasks in a CREB/BDNF pathway-dependent manner [14,19].…”

Cocoa, Chocolate, and Human Health

“…Besides flavanols, theobromine and other methylxanthines, peptides [8], and volatile aroma compounds [9] might also affect human health, e.g., theobromine, which seems to improve memory in rats [10]. Many studies, being intervention studies or epidemiological observations, do not focus on single compounds, but on cocoa as such; in some cases, enriched in polyphenols.…”