Apitherapy for Parkinson’s Disease: A Focus on the Effects of Propolis and Royal Jelly

Figure 1

Schematic summary of events contributing to the development of Parkinson’s disease. Multiple factors contribute to increased production of free radicals in age people. Meanwhile, the antioxidant capacity decreases with aging, which is associated with chronic increase of inflammatory markers [12, 14, 23, 24]. Inflammation along with free radicals induces morphological and functional mitochondrial alterations resulting in impaired energy production and more emission of free radicals. Injuries of the gastrointestinal tract caused by pathogens and ingested toxins stimulate the expression of the synaptic protein α-synuclein in enteric neurons. α-Synuclein then moves through the vagus nerve to be seeded in vulnerable neurons in the CNS [9–11]. In the meantime, the expression of genes involved in the synthesis of phospholipids of the biomembrane such as iPLA2-VIA decreases whereas microglia and astrocytes get activated and migrate in response to inflammation and auto-oxidation of dopamine, which trigger the expression of pathological genes such as α-synuclein and parkin [18]. As a result, α-synuclein pathology increases causing a widespread of initial seeds of α-synuclein to the vulnerable neighboring neurons. Consequently, continuous accumulation of α-synuclein results in the growth of intracellular tangles to form Lewy bodies inside dopaminergic neurons of the SNC contributing to neuronal dysfunction and death. α-Synuclein pathology moves from the SNC into the other brain regions such as the cortex leading to reduction of serotonergic and cholinergic markers such as serotonin and acetylcholine [11, 25]. Accordingly, PD patients undergo serious motor impairments, which decrease gait speed and increase the risk of fall, in addition to a range of other debilitating cognitive, psychiatric, and gastrointestinal symptoms such as poor cognitive performance, mood dysregulation, depression, sleep disturbance, nausea, and chronic constipation—which altogether lower quality of life and increase disability and mortality [20, 24]. ↑ denotes increase; ↓ denotes decrease; CNS: central nervous system; SNC: substantia nigra pars compacta; PD: Parkinson’s disease.