Regenerative Eﬀect of Growth Hormone (GH) in the Retina after Kainic Acid Excitotoxic Damage

International Journal of Molecular Sciences, 2019 · DOI: 10.3390/ijms20184433 · Published: September 10, 2019

Regenerative Medicine Neurology Genetics

Simple Explanation

Growth hormone (GH) is known to help protect nerve cells and encourage their growth in the brain. Studies have shown that GH can be helpful for people who have experienced brain injuries, strokes, spinal cord injuries, or cognitive problems. This study investigates if GH can help the retina, the light-sensitive tissue in the eye, recover after it has been damaged. The researchers caused damage to the chicken retina using a toxic substance called kainic acid (KA). Then, they administered GH injections over a period of 21 days. They found that GH helped restore the structure of the retina and increase the expression of genes that are important for nerve regeneration. The results suggest that GH can help the retina repair itself after injury by promoting cell growth and improving connections between nerve cells. These findings support the potential use of GH as a treatment to improve neural interconnections and promote neural stemness after retinal injuries.

Study Duration

3 weeks

Participants

One-day old chickens

Evidence Level

Not specified

Key Findings

1
GH treatment after KA-induced damage significantly restored the thickness of the inner plexiform layer (IPL) and inner nuclear layer (INL) in the retina.
2
GH increased the expression of genes involved in synaptogenesis (DLG1, NRXN1, GAP43), glutamate receptor subunits (NR1 and GRIK4), pro-survival factors (BDNF, Bcl-2 and TNF-R2), and Notch signaling proteins (Notch1 and Hes5).
3
GH facilitated the proliferative response of the injured retina, indicated by an increase in BrdU-positive cells in the KA-damaged retina.

Research Summary

This study investigates the regenerative effect of growth hormone (GH) on the retina after excitotoxic damage induced by kainic acid (KA) in chickens. The results showed that GH treatment promoted significant restoration of retinal layer thickness, particularly in the inner plexiform layer (IPL) and inner nuclear layer (INL). The study also found that GH increased the expression of several genes involved in regeneration, including synaptogenic markers, glutamate receptor subunits, pro-survival factors, and Notch signaling proteins. Furthermore, GH facilitated the early proliferative response of the injured retina. These findings suggest that GH has the potential to enhance neuroregeneration in the retina after injury by promoting cell proliferation, synaptic restoration, neurite growth, and pro-survival effects.

Practical Implications

Therapeutic Potential

GH could be a potential therapeutic agent for treating retinal damage and promoting regeneration after injury.

Synaptic Restoration

GH's ability to upregulate synaptogenic markers suggests it can aid in restoring neural connections in damaged retinas.

Cell Survival

The increased expression of pro-survival factors indicates GH's role in protecting retinal cells from death after injury.

Study Limitations

1
The study was conducted on chickens, and the results may not be directly applicable to humans.
2
The exact mechanisms by which GH promotes regeneration in the retina are not fully understood.
3
The long-term effects of GH treatment on retinal function were not assessed.

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