Neuroprotective effects of intramuscular ketamine in rabbit retinas after pars plana vitrectomy and silicone oil injection.

Abstract

PURPOSE:

To investigate potential retinal neuroprotective effects of intramuscular ketamine in rabbits after pars plana vitrectomy (PPV) and intravitreal silicone oil injection (SOI).

METHODS:

Twelve New Zealand rabbits (weight, 2.0-2.5 kg) underwent PPV with SOI in the right eye. Postoperatively, six rabbits received a daily intramuscular injection of ketamine for 4 weeks (ketamine-operated eyes), and six rabbits received a daily intramuscular injection of saline (saline-operated eyes). The retina from the left eye of each rabbit served as a control (ketamine-control and saline-control eyes). The animals were euthanized at 4 weeks after surgery. Qualitative and quantitative analyses were performed using the Zeiss Axiophot microscope and KS 400 software.

RESULTS:

Qualitative analysis using light microscopy demonstrated more extensive edema and cell disorganization in saline-operated retinas than in ketamine-operated, ketamine-control, and saline-control retinas. Quantitatively, the cell densities (cell/mm) in the outer nuclear layer (ONL), inner nuclear layer (INL), and ganglion cell layer (GCL) in saline-operated retinas were significantly (P < 0.05) lower than those in these layers in ketamine-operated, ketamine-control, and saline-control retinas. The cell density in the ONL in saline-operated retinas was 52% lower than that in ketamine-operated retinas, 55% lower than that in ketamine-control retinas, and 56% lower than that in saline-control retinas. The cell density in the INL in saline-operated retinas was 44% lower than that in ketamine-operated retinas, 48% lower than that in ketamine-control retinas, and 49% lower than that in saline-control retinas. The cell density in the GCL in saline-operated retinas was 60% lower than that in ketamine-operated retinas, 64% lower than that in ketamine-control retinas, and 64% lower than that in saline-control retinas.

CONCLUSION:

PPV with SOI was associated with retinal cell death and disorganization in rabbit eyes. Intramuscular ketamine administration provided protection against these effects.

• Authors: Mila W Paques, Renato Guizzo, Rubens C Siqueira, Antônio R M Silva, José A Cardillo, Ingrid U Scott, Harry W Flynn Jr, Wagner F Santos, Rodrigo Jorge
• Journal: Retina (Philadelphia, Pa.) (Retina) Vol. 26 Issue 2 Pg. 196-201 (Feb 2006) ISSN: 0275-004X [Print] United States
• PMID: 16467678 (Publication Type: Journal Article)

Chemical References

• Excitatory Amino Acid Antagonists
• Neuroprotective Agents
• Silicone Oils
• Ketamine

Topics

• Animals
• Apoptosis
• Cell Count
• Excitatory Amino Acid Antagonists (administration & dosage, therapeutic use)
• Female
• Injections
• Injections, Intramuscular
• Ketamine (administration & dosage, therapeutic use)
• Neurons (drug effects, pathology)
• Neuroprotective Agents (administration & dosage, therapeutic use)
• Postoperative Complications (prevention & control)
• Rabbits
• Retina (drug effects, pathology)
• Retinal Diseases (prevention & control)
• Silicone Oils (administration & dosage)
• Vitrectomy