Abstract
Abstract: :
Purpose: to evaluate the relation between retinitis pigmentosa (RP) and plasmatic level of adrenomedullin. Methods: we performed blood samples in a group of 22 patients affected by Retinitis Pigmentosa followed in our department of inherited retinal diseases of the University of Rome "La Sapienza". This group was compared with a control group of 22 healthy people age and sex matched. We performed a complete ophthalmological examination including: BCVA indirect ophtalmoscopy evaluating degree of RPE atrophy and severity of pigmentation, visual field, ERG. The study group included 15 patients with typical RP and 7 patients with syndromic RP (3 patients with a Cone–Rod dystrophy, 3 Uher’s Syndrome and one LMBB). Patients were sampled from cubital vein of 20 cc of blood in EDTA vacutainer. The determination of the adrenomedullin plasmatic concentration, after extraction and purification on Sep–Pak C–18 cartridge, was made with a radiological method (Phoenix Lab, Mountain View, CA, USA). Results: In the average population Adrenomedullin plasma concentration ranges between 13.7± 6.1 pg/ml while the average plasma ADM concentration in RP group was significantly increased, patients showed 22.54±9,224 pg/ml and differences evaluated between two groups with Student’s "t" test were highly statistically significant (p=0,0002). Although the lack of data for some categories we noted a very interesting increased of the average plasmatic level of ADM in all the categories: 3 US patients (35.83), 15 RP patients (20.7), 1 LMBB(20), patients. Considering the whole sample for what may concern the Syndromic RP the average plasma level of ADM is 26.59 and the mean for these diseases is higher than normal population and even for RP patients. Discussion: Considering literature data in our opinion in RP patients increased levels of ADM may be interpreted in two different ways: first of all ADM may be a response to photoreceptor damage according Udono as scarring process within the retina and this may be expressed by the correlation trend observed with intensity of retinal pigmentation. A secondary interpretation of ADM effect and very intriguing may be due to an attempt to generate a protective effect on photoreceptors cell damaged by the alterate phototransduction process. Infact as previously demonstrated ADM production in response to hypoxic stress that may mimic a metabolic damage similar to the phototransduction damage. Infact as experienced by berson, Stone and Vingolo supplementation of oxygen or Vitamin A in Retinitis pigmentosa patient may slower degenerative process, causing photoreceptors rescue.
Keywords: retinitis • retina • retinal pigment epithelium