A seasonal study of pinealocytes in the 13-lined ground squirrel, Spermophilus tridecemlineatus

McNulty, John A.; Dombrowski, Teresa A.; Spurrier, Wilma A.

doi:10.1051/rnd:19800408

Cited by 9 publications

(3 citation statements)

References 16 publications

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“…Interestingly, in humans serum melatonin levels show a bimodal annual curve with peaks in January and July (Arendt et al, 1978(Arendt et al, , 1979). At the pinealocyte nuclear level annual changes have been clearly demonstrated in golden hamsters (Mogler, 1958), bats (Quay, 1976) and 13-lined ground squirrels (McNulty et al, 1980), in some instances indications for bimodal curves are present. As the pertinent karyometric studies of pinealocytes were all carried out in different months of the year (Diehl, 1981, August;Becker and Vollrath, 1983, March;this study, April;Quay and Renzoni, 1966, unspecified) some of the discrepancies observed may be seasonal.…”

Section: Body Testicular and Epididymidal Weightsmentioning

confidence: 96%

Day/night changes of pineal gland volume and pinealocyte nuclear size assessed over 10 consecutive days

Diehl

Heidbüchel

Welker

et al. 1984

J. Neural Transmission

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Previous studies aimed at elucidating day/night changes of pineal gland size and pinealocyte nuclear volume have yielded contradictory results. The aim of the present investigation was to examine the above parameters over a period of 10 successive days, at 6-hour intervals under a lighting regimen of LD 12:12 (7 a.m. to 7 p.m.). It was found that changes in pineal gland volume could not be correlated with the light/dark phases; instead, a rhythm with a two-day period was encountered. Pinealocyte nuclear volume, by contrast, showed clear circadian changes, exhibiting troughs during photophase and peaks during scotophase. In this experimental series, the karyometric results conformed to the melatonin forming rhythm in the rat pineal gland as reported in the literature.

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Section: Body Testicular and Epididymidal Weightsmentioning

confidence: 96%

Day/night changes of pineal gland volume and pinealocyte nuclear size assessed over 10 consecutive days

Diehl

Heidbüchel

Welker

et al. 1984

J. Neural Transmission

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“…These results imply a decrease in the functional activity of the pinealocytes, as suggested by the concurrent decrease in melatonin and NAT contents. This concurrence adds credence to the use of nuclear size a5 a morphological parameter for monitoring pinealocyte activity [Legait et al, 1979;McNulty et al, 1980;Matsushima and Morisawa, 1981;Heidbuchel and Vollrath, 19831. Additional support for the validity of this measure is provided by circadian studies on pinealocytes in the superficial pineal of the rat which show that peak nuclear and nucleolar sizes [Quay and Renzoni, 19661 are correlated with RNA and protein content of the gland [Nir et al, 19711. In this study we have found the rhythm in pinealocyte nuclear volumes of the gerbil deep pineal gland to be out of phase with those in the superficial gland.…”

Section: Discussionmentioning

confidence: 65%

Effect of Acute Light Exposure Upon Melatonin Content, NAT Activity, and Nuclear Volume in the Gerbil Pineal Complex

Rollag

Welsh

Klein

1984

Journal of Pineal Research

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This report describes the response of both the superficial and deep components of the gerbil pineal gland to a 30-min pulse of fluorescent light at the time of the nocturnal peak in pineal activity. When gerbils were maintained in a 14 h light:10 h dark photoperiod, mean melatonin concentrations in the superficial pineal gland ranged between 72 and 108 pg/gland during the day and first 4 h of darkness, rose to a peak of 399 pg/gland 7 h after lights out, then returned to basal levels at the expected time of light onset. Pineal melatonin contents were reduced to daytime values within 30 min after exposure of gerbils to fluorescent light at the time of the nocturnal peak. These changes in superficial pineal melatonin content reflected the circadian pattern in serotonin N-acetyltransferase (NAT) activity, as would be expected if NAT controls melatonin synthesis. In addition to the reductions in NAT and melatonin content induced by nocturnal photic stimulation, there was a 30% reduction in mean pinealocyte nuclear volume. A nocturnal elevation in melatonin content but not in NAT activity occurred in the deep pineal gland. Unlike the superficial pineal gland, the deep pineal gland did not demonstrate a response in melatonin content, NAT activity, or pinealocyte nuclear volumes upon exposure of gerbils to light at the time of the nocturnal peak in superficial pineal activity.

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“…Sizes of pinealocytes or pineal glands have been reported to undergo seasonal variations in many wild animals under natural conditions (golden hamster, Mogler, 1958;dormouse, Legait et al, 1975;hare, Lincoln, 1976;bat, Quay, 1976;13-lined ground squirrel, Mc-Nulty et al, 1980;elephant seal, Griffiths and Bryden, 1981; white-footed mouse, Kachi and Quay, 1984). In these studies, the relationships between sizes of pinealocytes or pineal glands and seasons are not always consistent.…”

Section: Introductionmentioning

confidence: 99%

Effect of photoperiod on pineal gland volume and pinealocyte size in the chinese hamster, Cricetulus griseus

1990

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Male adult (200-day-old) Chinese hamsters (Cricetulus griseus) raised from weaning under either LD 16:8 or LD 8:16 were used. The pineal gland of the Chinese hamster consists of superficial (major) and deep (minor) components and a continuous, or interrupted, narrow parenchymal stalk interposed between them. The volume of the superficial pineal including the parenchymal stalk is greater under LD 16:8 than under LD 8:16. Under both photoperiods, pinealocytes in the superficial pineal have larger nuclei and more abundant cytoplasm than those in the deep pineal. Nuclei in the superficial pineal appear pale and usually have irregular profiles, whereas those in the deep pineal appear dark and have round profiles. In the superficial pineal, pinealocyte nuclei are larger, paler, and more irregular; and, in addition, nuclear density is lower under LD 16:8 than under LD 8:16. Similar, but less prominent, photoperiod-induced changes occur in the volume of the deep pineal, the size of pinealocytes, and pinealocyte nuclear morphology in the deep pineal. The results indicate that the development and differentiation of pinealocytes in both pineal portions may be advanced under long photoperiods and delayed under short photoperiods, although pinealocytes in the deep pineal may remain not fully differentiated even in adults. Since testicular weights and body weights are similar under both photoperiods, the photoperiod may exert marked influences on the development of the pineal gland without affecting reproductive activity and growth rates of animals.

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A seasonal study of pinealocytes in the 13-lined ground squirrel, Spermophilus tridecemlineatus

Abstract: Introduction.

Cited by 9 publications

References 16 publications

Day/night changes of pineal gland volume and pinealocyte nuclear size assessed over 10 consecutive days

Day/night changes of pineal gland volume and pinealocyte nuclear size assessed over 10 consecutive days

Effect of Acute Light Exposure Upon Melatonin Content, NAT Activity, and Nuclear Volume in the Gerbil Pineal Complex

Effect of photoperiod on pineal gland volume and pinealocyte size in the chinese hamster, Cricetulus griseus

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