Antidepressants The Cheese Effect

Antidepressants The Cheese Effect

ANTIDEPRESSANTS AND THE CHEESE EFFECT

According to Meyer & Quenzer (2019), dopamine, norepinephrine, and other similar substances such as epinephrine and serotonin constitute a small but significant group of neurotransmitters and hormones known as the catecholamine. The catecholamine is derived from the common chemical similarities shared by the members of this family of neurotransmitters. A pivotal structure of catechol and a nitrogen- containing moiety called an amine (Meyer & Quenzer, 2019). The catecholamines belong to an extensive group of transmitters called the monoamine or biogenic amines - compounds originating from living organisms. Epinephrine is often referred to as adrenaline.

 Whereas norepinephrine is referred to as noradrenaline. The adjectives, adrenergic and noradrenergic are used to describe adrenal and noradrenaline activity respectively. In catecholamine synthesis, the   enzyme, tyrosine hydroxylase catalyzes the rate-limiting process. There are several steps involved in this process. The synthetic pathway begins with the amino acid, tyrosine which is available in the food that we consume. Tyrosine is derived from dietary protein (Meyer& Quenzer, 2019).

There are two essential enzymes involved in the conversion of tyrosine to catecholamine, tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC). In the first and second synthetic processes, Dopamine is produced. The third process proceeding further with the aid of the third enzyme, dopamine. Meanwhile, dopamine B-Hydroxylase (DBH) converts dopamine to norepinephrine. Dopamine can also be synthesized by converting the precursor, L-DOPA to dopamine. Meanwhile, L-DOPA has been the therapeutic agent of choice in the treatment of Parkinson’s disease because it easily crosses the blood brain barrier with   less adverse effects. Dopamine itself, is administered also as carbidopa in combination with levodopa to minimize side effects in the treatment of Parkinson’s disease. Drugs that inhibit catecholamine synthesis include the a-methyl-para-tyrosine (AMPT).

 According to Meyer & Quenzer (2019), the metabolism of the catecholamine involves two enzymes, catechol-o-methyltransferase (COMT) and monoamine oxidase: MAO-A and MAO-B. The importance of each MAO subtype depends on the neurotransmitter that is being metabolized. Norepinephrine is metabolized by MAO-A in humans and rodents (Meyer & Quenzer, 2019). While dopamine is metabolized by MAO-B in humans. Dopamine is metabolized by MAO-A in rodents. The antidepressants, paroxetine and moclobemide work to elevate the concentrations of the neurotransmitter, serotonin (by inhibiting reuptake of serotonin). While moclobemide decreases the rate at which serotonin is metabolized by inhibiting MAO-A. Excessive combination of serotonergic agents results in what is known as serotonin crisis or serotonin syndrome.

The action of the two metabolizing enzymes, COMT and MAO of the catecholamine yields the catecholamine metabolites.

 According to Meyer & Quenzer (2019), the metabolism of dopamine in humans yields the metabolite, homovanillic acid (HVA). While the metabolism of norepinephrine yields the metabolite, 3-methoxy-4-hydroxy-phenylglycol (MHPG) and Vanillylmandelic acid (VMA). Vanillylmandelic acid is eventually excreted in the urine.

The concentration of these metabolites in blood and urine provides approximate prediction of catecholaminergic activity in nervous system, and also used to determine the potential involvement of neurotransmitters in depression or schizophrenia. Drugs that inhibit the action of the catecholamine result in concentration of these neurotransmitters.

 According to Meyer & Quenzer (2019), drugs such as phenelzine (nardil) and tranylcylcypomine (parnate) are non-selective MAO-inhibitors that inhibit both MAO-A and MAO-B used in the treatment of clinical depression. Selegiline and rasagiline are inhibitors of MAO-B. While moclobemide as mentioned earlier, is selective inhibitor of MAO-A. COMT inhibitors are used as adjuvant therapy to potentiate efficacy of L-DOPA in Parkinson’s disease treatment.

According to Finberg etal (1983), inhibitors of the enzyme, MAO has been used therapeutically for the treatment of affective disorders. However, their use falls out of favor due to reports of serious hypertensive reaction when patients treated with MAOI drugs consume foods rich in protein such as yellow cheese that is high in catecholamine derivative substance, tyramine. Tyramine or (4-hydroxyphenethylamine, para-tyramine) is commonly found in nature as it’s readily formed from its precursor amino acid, tyrosine by the action of the enzyme, aromatic amino acid decarboxylase (AAADC).

Tyramine oxidase is an MAO that acts on tyramine receptor or other MAO enzymes such as serotonin, catecholamine, benzylamine, and beta-phenylethylamine (Baker etal, 2011). Tyramine is a receptor for both isoforms of MAO, MAO-A and MAO-B. Tyramine stimulates alpha and beta adrenoceptors in the blood, producing vasodilation.

To elicit antidepressant effect using MAO inhibitor, it’s necessary to block MAO-A, the subtype of MAO involved in deamination of noradrenaline and serotonin (5-HT). However, the inhibition of MAO-A alone will elevate tyramine effects, also known as the cheese effect that includes acute hypertension well beyond 200 mmHg when engaged in various common endurance activities. Modest levels of physical endurance elevate the systolic blood pressure even higher, in excess of 400 mmHg.

According to Sandler (1981), it’s commonly accepted that the monoamine oxide (MAO) inhibiting moiety of drugs have a relevant role in the treatment of clinical depression. Intervention in cheese effect includes treating acutely elevated blood pressure only if there is evidence of end organ injury and only in supervised care setting (Finberg etal, 1983. In conclusion, according to Corn (1990), a new group of reversible selective inhibitors of MAO provide the benefit of antidepressant efficacy analogous to older irreversible non-selective drugs devoid of the cheese effect, and restrictive diet. This has played a significant role in the decline of the use of the MAOI antidepressants. Also, the availability of the newest class of antidepressants, including the paroxetine and fluoxetine provide more effective alternatives to the monoamine oxidase inhibitors, thereby eliminating the risk of tyramine effect.

References

Corn, T. H. (1990). Reversible Inhibitors of Monoamine Oxidase A: Antidepressants Without Cheese Effect? International Review of Psychiatry2(2), 187–192. https://doi.org/10.3109/09540269009028282

 Finberg, J.P.M. & Gillman, K. (2011). Selective inhibitors of monoamine oxidase type B and the “cheese effect”, Douce, P. & Youdim, M.B.H. (eds.). International Review of Neurobiology, Academic Press, Volume 100, Pages 169-190https://doi.org/10.1016/B978-0-12-386467-3.00009-1Get rights and content

Meyer, S.J. & Quenzer, L.F. (2019). Psychopharmacology: Drugs, the Brain, and Behavior. Oxford University Press. www.oup.com

Ramachandraih, Chaitra T.; Subramanyam, Narayana1; Bar, Kral Jurgen2; Baker, Glen3; Yeragani, Vikram K.4, Antidepressants: From MAOIs to SSRIs and more. Indian Journal of Psychiatry 53(2): p 180-182, Apr–Jun 2011. | DOI: 10.4103/0019-5545.82567

Sandler M. (1981). Monoamine oxidase inhibitor efficacy in depression and the ‘cheese effect.’ Psychological Medicine. 1981;11(3):455-458. doi:10.1017/S0033291700052764