Hypothyroidism Enhanced Ectonucleotidases and Acetylcholinesterase Activities in Rat Synaptosomes can be Prevented by the Naturally Occurring Polyphenol Quercetin

Abstract

Thyroid hormones have an influence on the functioning of the central nervous system. Furthermore, the cholinergic and purinergic systems also are extensively involved in brain function. In this context, quercetin is a polyphenol with antioxidant and neuroprotective properties. This study investigated the effects of (MMI)-induced hypothyroidism on the NTPDase, 5'-nucleotidase, adenosine deaminase (ADA), and acetylcholinesterase (AChE) activities in synaptosomes of rats and whether the quercetin can prevent it. MMI at a concentration of 20 mg/100 mL was administered for 90 days in the drinking water. The animals were divided into six groups: control/water (CT/W), control/quercetin 10 mg/kg, control/quercetin 25 mg/kg, methimazole/water (MMI/W), methimazole/quercetin 10 mg/kg (MMI/Q10), and methimazole/quercetin 25 mg/kg (MMI/Q25). On the 30th day, hormonal dosing was performed to confirm hypothyroidism, and the animals were subsequently treated with 10 or 25 mg/kg quercetin for 60 days. NTPDase activity was not altered in the MMI/W group. However, treatment with quercetin decreased ATP and ADP hydrolysis in the MMI/Q10 and MMI/Q25 groups. 5'-nucleotidase activity increased in the MMI/W group, but treatments with 10 or 25 mg/kg quercetin decreased 5'-nucleotidase activity. ADA activity decreased in the CT/25 and MMI/Q25 groups. Furthermore, AChE activity was reduced in all groups with hypothyroidism. In vitro tests also demonstrated that quercetin per se decreased NTPDase, 5'-nucleotidase, and AChE activities. This study demonstrated changes in the 5'-nucleotidase and AChE activities indicating that purinergic and cholinergic neurotransmission are altered in this condition. In addition, quercetin can alter these parameters and may be a promising natural compound with important neuroprotective actions in hypothyroidism.

Antioxidant, hepatoprotective, genoprotective, and cytoprotective effects of quercetin in a murine model of arthritis

“…60 Besides, it was found that quercetin treatment reversed the rise in ROS and TBARS levels in the groups with arthritis. This corroborates with other studies that have demonstrated that quercetin reduced ROS and TBARS levels, 31,61 probably due to the hydroxyl groups in this flavonoid, which inactivate highly reactive species. 62 Previous studies have also shown that quercetin prevents lipid peroxidation and eliminates superoxide radicals 63,64 by scavenging free radicals, therefore, delaying oxidative pathwaymediated cell injury, ensuring protection against lipid peroxidation, and chelating metal ions.…”

Differential protection of black-seed oil on econucleotidase, cholinesterases and aminergic catabolizing enzyme in haloperidol-induced neuronal damage of male rats

“…The cholinergic system is responsible for normal functioning of both the CNS and peripheral nervous system [Baldissarelli et al . 2016].…”

“…The cholinergic system is responsible for normal functioning of both the CNS and peripheral nervous system [Baldissarelli et al 2016]. Acetylcholine (ACh) is the key neurotransmitter of the cholinergic system, playing vital roles such as learning, memory, movement control, and modulation of cerebral blood circulation [Lovinger, 2010].…”

Neuroprotective Effects of Quercetin in Alzheimer’s Disease

“…Moreover, quercetin exhibits greater potency for the inhibition of AChE and BChE than its glycosidal form, rutin. Previous studies have posited the presence of a sugar moiety in the molecule is essential for its enzymatic inhibition [115,128,129]. Jung et al (2007) studied the acetylcholinesterase inhibiting the potential of flavonoids, including quercetin isolated from Agrimonia pilosa and they reported the IC50 value of quercetin to be 19.8 [130].…”