GINGER EXTRACT IMPROVES OCULAR BLOOD FLOW

 

It is known that glaucoma can develop or progress even in the presence of normal IOP. Deranged ocular blood flow (OBF) is suspected to be a major risk factor in such cases. Acute blood flow reduction in the retina contributes to axonal damage and retinal ganglion cell (RGC) death.

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Endothelin-1 (ET-1), one of the most potent vasoconstrictor peptides, has been implicated in glaucoma pathogenesis. Several studies have shown that intravitreal injection of ET-1 induces optic neuropathy in rodent models.

Takahashi and colleagues from Tohoku University Graduate School of Medicine have studied the effect of a ginger extract on optic nerve head blood flow (ONH BF) under ET-1 stimulation.

The researchers used laser speckle flowgraphy to study the ONH BF impairment profile under ET-1 stimulation. The main LSFG variable, expressed in arbitrary units, is termed mean blur rate (MBR) and indicates relative blood flow.

To establish the ONH BF impairment profile under ET-1 stimulation, brown Norway rats were administered an intravitreal injection of ET-1 under anesthesia. They were subsequently given ginger extract sublingually to assess its effect on ONH BF in both normal and ET-1-induced ischemic conditions.

The ginger extract contained 50% red ginger [Zingiber ofcinale var. rubra] extract and 50% cyclodextrin. The active ingredient in the ginger extract was [6]-shogaol. A previous study has shown that [6]-shogaol increases intestinal blood flow (IBF), and that this effect was mediated by the calcitonin gene-related peptide (CGRP) and its receptor.

The percentage changes in MBR in the case group were compared to the sham (PBS injection and non-intake). In the case (ET-1 injection and ginger extract intake) group, %MV was 64.7±19.2%. In the control (ET-1 injection and non-intake) group, %MV was 44.0±20.6%.

Percentage MBR in the vessels (%MV) and percentage MBR in the tissues (%MT) were significantly higher in the ginger extract intake group than in the non-ginger extract intake group (P=0.039, P=0.046, respectively), indicating that the ginger extract ameliorated the dysregulation of ONH BF. Similarly, the overall MBR (%MA) in the ginger extract intake group tended to be higher than the non-ginger extract intake group (P=0.068).

The study demonstrates that a ginger extract containing [6]-shogaol can increase ONH BF under conditions of good health as well as ischemia, independently of BP and IOP. The agent can act as a useful treatment modality for NTG and help prevent optic neuropathy induced by vascular dysregulation, such as that seen in NTG.

REFERENCE:

Takahashi N, Sato K, Kiyota N, Tsuda S, Murayama N, Nakazawa T. A ginger extract improves ocular blood flow in rats with endothelin-induced retinal blood flow dysfunction. Sci Rep. 2023 Dec 20;13(1):22715. doi: 10.1038/s41598-023-49598-w. PMID: 38123793; PMCID: PMC10733345.

A blind bat eating ginger