Avtor/Urednik     Hawlina, M
Naslov     Role of melatonin and dopamine in an animal model of hereditary retinal dystrophy
Tip     monografija
Kraj izdaje     London
Založnik     United medical and dental school of Guys and St. Tomas's
Leto izdaje     1995
Obseg     str. 224
Jezik     eng
Abstrakt     The renewal process of the retinal photoreceptors was studied with a combination of electroretinography (ERG) and pharmacological techniques in normal and dystrophix Royal College of Surgeons (RCS) rats, in which thephagocytosis of the old photoreceptor discs by the retinal pigment epithelium (RPE) is defective. The ERG showed that the circadian rhythm of the renewal process is manifested by a diurnal variation in the trans-pigment epithelizn potential, the ERGc-wave, which was lowest at 1-1.5 hours after the expected light-on time, when the disc phygocytosis is at its peak. However, the rhythm of the c-wave amplitude was found significantly attenuated and the absolute c-wave amplitudes, supernormal in the dystrophix rats as compared to the controls during the period preceding retinal degeneration. The normal renewal process is known to be regulated by a precise balance between the retinal melatonin and dopamine. In RCS rats, however, a radioimmunoassay revealed that he melationin content was nearly twice as high than in the control retinas, which may be causally associated with the disturbance of RPE phagocytosis. The effects of the chronic administration of dopamine D2 agonist, bromocriptine, which decreases the retinal melatonin level, was thus examined by the ERG. The results showed significantly better preserved ERG responses in bromocriptine-treated than in vechicle-treated than in vehicle-treated dystriohic rats after 30-day treatment. Inversy, in the normal rats, bromocriptine caused a marked reduction of ERG responses. The results of this thesis demonstrate: 1) that early functional distrubances in the photoreceptor renewal process in the RCS rats are primarily reflected in the ERG c-wave; that a disturbance of the local milieu of the neuromodulatory substances responsible for the process of photoreceptor renewal is present in the RCS rat (truncated).
Deskriptorji     RETINAL DEGENERATION
PHOTORECEPTORS
MELATONIN
DOPAMINE
BROMOCRIPTINE
ANIMALS, LABORATORY
ELECTRORETINOGRAPHY
PHAGOCYTOSIS
CIRCADIAN RHYTHM
RETINA
RADIOIMMUNOASSAY