Scholarly article on topic 'Role of probiotics as memory enhancer'

Role of probiotics as memory enhancer Academic research paper on "Veterinary science"

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Indian Journal of Pharmacology
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Academic research paper on topic "Role of probiotics as memory enhancer"

Role of probiotics as memory enhancer

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DOI: 10.4103/0253-7613.111917

The health benefits gained from the ingestion of probiotics have been widely reported in the scientific literature. However, definitive mechanism(s) have yet to be identified for the ability of orally administered bacteria to modulate a number of biological processes ranging from the production of inflammatory cytokines by immune cells within the gastrointestinal tract to the adhesion of pathogenic bacteria to the mucosal gut wall. Whereas multiple mechanisms may be operative in these situations, an alternative hypothesis described is that there may be a shared mechanism that essentially links the neural and immune responses to probiotic administration that leads to the claimed prophylactic effects.111

The idea that probiotic bacteria administered to the intestine could influence the brain seemed almost unbelievable. 121 One of the researches demonstrated the ability of probiotics to influence psychological states imply that the mechanism(s) by which probiotics influence the host may extend beyond those, which address their well-recognized ability to influence immune-related pathways. For example, administration of the probiotic Bifidobacterium infantis to rats subjected to a forced swim test resulted in neurochemical alterations in addition to attenuation of pro-inflammatory responses that suggested a potential antidepressant capability for the administered probiotic. In human volunteers, as well as in a rat model, administration of a probiotic formulation consisting of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175A significantly attenuated psychological distress and reduced anxiety-like behavior, respectively.131 This ability of a probiotic to function as an anxiolytic may have profound clinical applications given the well-documented occurrence of psychosocial abnormalities that accompany a number of gastrointestinal disorders such as those associated with chronic intestinal inflammation.

In Mark Lyte's hypothesis paper, such a concept is supported by studies showing that microbes can produce, and respond to, neurochemicals. These compounds can induce neurological and immunological effects in the host. The immunomodulatory effects of probiotics have been well-documented, but so far not linked specifically with neurological outcomes.111

The researchers, from the University of Toronto, Massachusetts Institute of Technology, and University of Calgary, found that the mice did not display behavioral abnormalities while infected or even after the infection cleared. However, when exposed to stress, they displayed memory dysfunction. When the infected mice were given

daily probiotics prior to, and during, infection, memory was not impaired.141 They concluded that "probiotics could provide benefit in relation to behavioral abnormalities in patients with irritable bowel syndrome."141

Many Irritable Bowel Syndrome (IBS) patients report difficulty with memory, often attributing it to the pain they suffer during flare-ups. This study suggests that probiotics are not only helpful in preserving memory during bouts with intestinal infection, but necessary, proven by the deficits exhibited by the mice with completely sterile systems. It also suggests that rather than remedies for memory problems, such as Omega 3, which addresses brain health, a regular diet that includes probiotics may prove to be more effective.141

To date, there is evidence showing anti-inflammatory effects of lactobacilli in the gut, but less strong evidence that they or bifido bacteria confer immunomodulatory effects in inflammatory bowel disease patients that induce clinically significant amelioration of the disease. This does not rule out strains being identified with this benefit in the future, or being used to induce neurological effects (against pain, depression) in conjunction with immunomodulatory drugs that target the site of inflammation.

Studies on clinical populations, such as the chronic fatigue syndrome, and fibromyalgia, where lower levels of bifidobacterium and higher levels of lactic acid bacteria have been reported, have found evidence to suggest that poorer gut health is correlated with more severe neurological and cognitive deficits such as nervousness, memory loss, forgetfulness, and confusion. There have been few studies to directly assess the effects of probiotics on cognition. A study by Benton et al.,151 has been one of the few chronic intervention studies to directly investigate the effects of probiotics on cognition. However, the effects on cognition were not in the direction that might have been expected. At day 20 of the intervention, individuals in the probiotic group were found to perform significantly worse on a test of semantic memory in comparison with placebo.151 However, considering the scarcity of other studies to investigate the cognitive effects associated with probiotics, further research is required to corroborate these findings.

Microbial endocrinology-based hypothesis thus can guide the selection of probiotics based on a matching of the specific probiotic organism's capacity to produce a particular neurochemical and the physiological or behavioral condition that is responsive to that neurochemical. Thus probiotic treatment could be tailored to treat the pathology and/or symptomology associated with specific disease or psychological states.

Shubham Misra, Bikash Medhi

Department of Pharmacology, Post Graduate Institute of Medical Education and Research, Chandigarh, India

Correspondence to:

Dr. Bikash Medhi, E-mail:


1. Lyte M. Probiotics function mechanistically as delivery vehicles for neuroactive compounds: Microbial endocrinology in the design and use of probiotics. Bioessays 2011;33:574-81.

2. Bienenstock J, Collins S. 99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: Psycho-neuroimmunology and the intestinal microbiota: Clinical observations and basic mechanisms. Clin Exp

Immunol 2010;160:85-91.

3. Irvine EJ. Review article: Patients' fears and unmet needs in inflammatory bowel disease. Aliment Pharmacol Ther 2004;20:54-9.

4. Gareau MG, Wine E, Rodrigues DM, Cho JH, Whary MT, Philpott DJ et al., "Bacterial infection causes stress-induced memory dysfunction in mice." Gut 2011,60:307-17.

5. Benton D, Williams C, Brown A. Impact of consuming a milk drink containing a probiotic on mood and cognition. Eur J Clin Nutr 2007;61:355-61.

Isolated chick ileum for bioassay of acetylcholine

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DOI: 10.4103/0253-7613.111927

Current restrictions in experiments with laboratory animals prompted the search for alternate tissues for biological testing. Tissues from poultry, sheep, goats, cattle, fish, etc., usually consumed for food, were suggested.111 We investigated ileum from chicks sacrificed for food as a possible alternative in 20 experiments.

The small intestine in chick is a long and uniform in the diameter. Its circular muscles are 3 times thicker than the longitudinal muscles.

From a local government registered meat shop fresh intestine of chicken was collected into a flask containing 500 ml

"chick" solution, transported immediately to laboratory and kept aerated. Composition of chick solution: NaCl 118.4 mM, KCl 4.6 mM, CaCl2 2.0 mM, MgCl2 0.5 mM, KH2PO4 1.2 mM, NaHCO3 25 mM, glucose 11.1 mM, and sucrose 13.2 mM.121

In initial experiments with Tyrode (3) or Chick Solution (10) the bath was maintained at 37°C. When the tissue responses to acetylcholine (ACh) were not uniform, taking a long time for relaxation, we changed to chick solution maintained at 42°C|21 in the last 7 experiments.

The piece of ileum (approximately 2 cm) with contents washed with chick solution was mounted in 10 ml organ bath kept at 42°C and aerated. It was rested for 1 h under 1 g tension. The isotonic responses of the tissue were recorded on kymograph with frontal ink writing lever at a magnification of seven. ACh, atropine (ATR) and all other chemicals used were of analytical reagent (AR) grade.

At 1 |ig doses the preparation responded to ACh, but not histamine and 5 hydroxy tryptamine (5-HT). ACh was used in all experiments applying a cycle of contact to ACh for 30 s at 3 min intervals. Ach (0.5-8 ^g) produced dose dependent contractions added to 10 ml bath.

Figure 1: Chick ileum (competitive antagonism of acetylcholine [ACh] by atropine [ATR]) physiological chick solution temperature: 42°C ACh: 2 |xg ATR: 2 ^g

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