Effects of time, photoperiod, and pinealectomy on ocular and plasma melatonin concentrations in the chick

Osol, George; Schwartz, Bernard; Foss, D. C.

doi:10.1016/0016-6480(85)90114-5

Cited by 35 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar compensatory rises in ocular melatonin contents after pinealectomy have been reported in the rat, chicken, and pigeon (Osol et al, 1985;Reiter et al, 1983;Vakkuri et al, 1985;Yu et al,1981). These results suggest the involvement of the pineal organ in the regulation of the phase and/or amplitude of ocular melatonin rhythms.…”

Section: Discussionsupporting

confidence: 72%

Ocular Melatonin Rhythms in the Goldfish, Carassius auratus

et al. 1997

View full text Add to dashboard Cite

Ocular melatonin rhythms in the goldfish were studied and compared to those in the pineal organ and plasma. Under light:dark (LD) of 12 h light:12 h dark, melatonin contents in the eye as well as the pineal organ and plasma exhibited clear day-night changes with higher levels at mid-dark than at mid-light. However, melatonin contents in the eye at mid-light and mid-dark were approximately 100 and 9 times greater than those in the pineal organ, respectively. Day-night changes of ocular melatonin persisted after pinealectomy, which abolished those in plasma melatonin under LD 12:12. Ocular melatonin contents in the pinealectomized fish at mid-light were significantly higher than those in the sham-operated control. Under constant darkness (DD), circadian melatonin rhythms were observed in the eye but damped on the 3rd day, whereas plasma melatonin rhythms generated by the pineal organ persisted for at least 3 days. Under constant light, ocular melatonin contents exhibited a significant fluctuation with a smaller amplitude than that under DD, whereas plasma melatonin remained at low levels. These results indicate the involvement of LD cycles, a circadian clock, and the pineal organ in the regulation of ocular melatonin rhythms in the goldfish.

show abstract

Section: Discussionsupporting

confidence: 72%

Ocular Melatonin Rhythms in the Goldfish, Carassius auratus

et al. 1997

View full text Add to dashboard Cite

show abstract

“…There appears, therefore, to be significant species-specific differences in whether or not melatonin synthesized in the eyes can be secreted into the blood. It is clear from our results that a compensatory mechanism for maintaining circulating levels of melatonin in the absence of the pineal (Osol et al, 1985) did not occur.…”

Section: Discussioncontrasting

confidence: 56%

Pineal Gland and Ocular Influences on Turkey Breeder Hens.

Siopes

Underwood

1987

Poultry Science

View full text Add to dashboard Cite

The influence of the pineal gland and the eyes on reproductive performance of turkey hens was examined. Photosensitive, yearling Large White turkey breeder hens underwent pinealectomy (PX) or bilateral ocular enucleation (EX) or both while held on 8 hr of light per day (8L:16D) and were then photoinduced into a typical 20-week egg laying period by exposing the birds to 16 hr of light per day (16L:8D). Data were obtained for the time to first egg (sexual maturation), rate of egg laying, percent fertility, percent hatchability, weight of poults at hatching, and plasma melatonin levels. A significant interaction between PX and EX treatments occurred in the sexual maturation data only. Pinealectomy significantly delayed (P less than .05) the onset of egg laying (by 4.1 to 7.4 days) compared with the other treatment groups. No other significant differences in onset of lay occurred. Pinealectomy significantly depressed egg production during weeks 11 to 20 of lay and this resulted in fewer eggs per PX hen over the 20-week study (85.4 vs. 93.3 eggs in the PX and pineal intact groups, respectively). Enucleation did not significantly affect egg production. Neither the PX nor the EX treatment significantly affected fertility or hatchability determined at 4-week intervals over the 20-week study. However, poult weights were significantly greater as a result of either PX (P less than .01) or EX (P less than .05) treatment. Nocturnal elevation of plasma melatonin was significantly reduced by PX but not by EX. It was concluded that an extraretinal, extrapineal photoreceptive mechanism is operative in turkey breeder hens but both the pineal gland and the eyes can influence certain reproductive parameters.

show abstract

“…We induced form-deprivation myopia in day-old White Leghorn chicks under aseptic conditions and ether anesthesia using one of three uniocular procedures: eyelid suture (6,8), translucent plastic goggle, or transparent but imagedegrading plastic goggle (7). Maintained on a 12-hr light/dark cycle, the birds were killed at ages up to 4 weeks by decapitation or by perfusion with Zamboni's fixative (17) under deep pentobarbital anesthesia.…”

Section: Methodsmentioning

confidence: 99%

“…Observations after unilateral visual deprivation have indicated that retinal image quality influences postnatal growth. Deprivation of form vision in juvenile monkeys (2)(3)(4), chicks (5)(6)(7)(8)(9), or humans (10)(11)(12) disrupts normal regulation and leads to excessive eye size; distant images now focus in front of the retina, causing a myopic refractive error. This link of visual quality to eye size implicates the nervous system in growth control.…”

mentioning

confidence: 99%

Retinal dopamine and form-deprivation myopia.

Stone

Lin

Laties

et al. 1989

Proc. Natl. Acad. Sci. U.S.A.

360

323

View full text Add to dashboard Cite

Investigation of retinal neurochemistry in a well-defined chick model of form-deprivation myopia indicated that dopamine and its metabolite 3,4-dihydroxyphenylacetic acid are reduced in myopic as compared to control eyes. The reduction in retinal dopamine is evident only during light adaptation and is accompanied by a decreased rate ofdopamine biosynthesis. To test whether the alteration in dopamine metabolism is related to eye growth, agents known to interact with dopamine receptors were administered locally to deprived eyes. Remarkably, the expected growth in the axial dimension was reduced, while that in the equatorial dimension was not. Therefore retinal dopamine may participate in the pathway linking visual experience and the postnatal regulation of the eye's growth in the axial dimension. The mechanism for control of chick eye growth in the equatorial dimension remains unknown.Eye growth during normal childhood development coordinates with progressive changes in the optical power of the cornea and lens to maintain image focus on the plane of the retina (1). Observations after unilateral visual deprivation have indicated that retinal image quality influences postnatal growth. Deprivation of form vision in juvenile monkeys (2-4), chicks (5-9), or humans (10-12) disrupts normal regulation and leads to excessive eye size; distant images now focus in front of the retina, causing a myopic refractive error. This link of visual quality to eye size implicates the nervous system in growth control. Moreover, recent observations hint that such control is largely local. (i) Form-deprivation myopia in both monkeys and chicks takes place even after optic nerve transection interrupts the direct pathway from retina to brain (3, 13). (ii) Application of a partial occluder in chicks to restrict vision either in the nasal or temporal visual field induces excessive eye growth only along the corresponding ocular dimension. For example, occlusion of the nasal visual field causes excessive growth of the temporal part of the globe (14-16). We now report in avian myopia that neonatal deprivation of form vision alters retinal dopamine metabolism at the same time as the eye enlarges. Under the identical condition, ocular administration of dopaminerelated agents hinders the expected elongation of the eye in the axial but not in the equatorial dimension. These findings buttress the hypothesis of local growth control and suggest the participation of retinal dopamine in the regulatory sequence. They also speak for separate mechanisms underlying the regulation of axial and equatorial growth of the eye.

show abstract

Effects of time, photoperiod, and pinealectomy on ocular and plasma melatonin concentrations in the chick

Cited by 35 publications

References 19 publications

Ocular Melatonin Rhythms in the Goldfish, Carassius auratus

Ocular Melatonin Rhythms in the Goldfish, Carassius auratus

Pineal Gland and Ocular Influences on Turkey Breeder Hens.

Retinal dopamine and form-deprivation myopia.

Contact Info

Product

Resources

About