Peptides and Brain Health
Peptides play a crucial role in maintaining brain health. They can cross the blood-brain barrier and influence brain function, potentially improving memory, learning, and cognitive function. Research has shown that certain peptides can even promote neurogenesis, the process of creating new neurons in the brain.
What Are Peptides?
Peptides are short chains of amino acids (which are building blocks of protein), consisting of 2 to 50 amino acids with a molecular weight of less than 10kDA [1]. We can look at them as “smaller” versions of proteins and like proteins these chains of amino acids -peptides- can differ in structure and molecular weight [1].
Peptides are versatile biopolymers (polymers derived from living organisms) which can penetrate cell membranes [2]. They also can serve as regulators of the functions of the endocrine, nervous and immune system thus have a wider range of biological functions. For instance, they can interfere with protein-protein interactions [3]. They can penetrate through nuclear membranes into the nuclei of cells and interact with nucleosomes, the histone proteins or even with DNA [4].
Because of their wide range of functions, peptides are used in the pharmaceutical industry as antioxidants, antihypertensive, anticoagulant and immunomodulatory compounds [1]. Recently, they have also been used for delivering drugs as molecular building blocks or cell-targeting ligands [5].
How Can Peptides Affect Our Brain, Memory and Learning?
Peptides play a significant role in the functioning of our nervous system by affecting physiological processes [6].
First of all, peptides can influence our brain by modulating neuronal circuits. In particular, they can alter cerebral protein synthesis, RNA synthesis, protein phosphorylation and neurotransmitter turnover [7]. These modulations then in return can affect the neurons.
Studies have found that peptides can also impact learning and memory processes. Neuropeptides (small peptides in the brain) which are related to adrenocorticotropic and melanocyte-stimulating hormones can affect motivational processes and the ones related to vasopressin are involved in memory processes [8].
However, when our brain is stressed or overcoming aversive events, neuropeptides can alter the permeability of the blood-brain barrier (BBB), which allows for the transport of essential substances. This then ensures that substances necessary for proper brain function are delivered [9].
Furthermore, peptides can also impact our behaviour, especially in neuropsychiatric conditions like depression, dementia or schizophrenia. It appears that peptides can affect our social, sexual and even material behaviour [6].
Lastly, it peptides can have a therapeutic role in the brain. They can be used as therapeutic agents for central nervous system disorders but also can target diseases due to altered BBB-peptide interactions [10].
Can Peptides Improve Our Brain Health?
The question now is, with all these possibilities on how the peptides affect our brain, can they improve our brain health?
According to some studies, natriuretic peptides (peptides ensuring cardiovascular, renal, and endocrine homeostasis), which are abundant in the central nervous system seem to regulate brain functioning. High systemic levels of natriuretic peptides are associated with cognitive impairment [11].
Peptides, which are key regulators in cellular and intercellular physiological responses, have shown great promise for the treatment of various central nervous system diseases [12]. They are involved in the regulation of neurovascular and blood-brain barrier integrity, neuro-inflammation, neuroprotection, synaptic transmission, and brain fluid homeostasis [11].
Naturally derived peptides seem to exhibit neuroprotective effects. They are associated with protection against apoptosis (cell death), with acetylcholine activity (acetylcholine is an important neurotransmitter) and the inhibition of oxidative stress and inflammation [13].
Peptides therefore have a potential in improving the brain health, although more research needs to be done in order to specifically address which areas of the brain may be improved.
In addition, the delivery of peptides to the brain is also challenging. Peptides have low metabolic stability, which decreases the duration of their action, poor penetration through the BBB and there are difficulties with their administration as well [14]. However, there are new strategies under development such as using peptides by conjugation to a polymer (e.g nanoparticles) which can help with the delivery of peptides into the brain [12].