ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00189.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Melatonin's effects were studied in male golden hamsters (Mesocricetus auratus) distributed among five surgical groups (nonoperated, sham‐pinealectomized, sham‐pinealectomized plus black plastic shielding of the pineal region, pinealectomized, and pinealectomized plus black plastic shielding of the pineal region) and three injection groups (vehicle only, 25 μg melatonin, and 2,500 μg melatonin). Injections (s.c.) were daily for 28 d at L11to L11.75in a (light:dark) L:D 14:10 artificial photoperiod. Animals (N = 112) were killed and dissected on the day after the last injection (at 55–65 d of age). None of rhe surgical procedures affected weights of eyes or their parts, nor did they influence the effects of administered melatonin on the eyes. Melatonin caused an increase in absolute and relative eye weight and an increase in fluid content of intraocular space. The magnitudes of these effects were positively related to melatonin dose. These same eyes had a progressively lower weight of nonlenticular tissues with low to high doses of melatonin, probably in relation to greater fluid content, and suspected increase in intraocular pressure. Lens wet and dry weights were significantly greater in animals receiving melatonin, but only at the high dose. These actions of melatonin are likely to be direct and are shown to not require the presence of the pineal. Experiments of other designs are suggested in order to determine whether the effects of the low, near physiological, dose of melatonin represent physiological actions of endogenous melatonin, synthesized and released within the eye. However, effects of large doses of melatonin on the eye are still noteworthy in relation to interpretation of experiments employing such dosages, and of disease states involving changes in intraocular p

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00190.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Thyroxin (T4) and triiodothyronine (T3) were measured by radioimmunoassay in serum of hamsters sacrificed at 4‐hr intervals throughout the daily light‐dark cycle (14L/10D). Both T4 and T3 concentrations increased significantly during the L period of the daily cycle and decreased during the D period of the cycle; A.M. versus P.M. differences in free thyroxin indices (FTI) were also studied using the T4 and T3 uptake assays of Nuclear Medical Laboratories (Dallas, Texas). The free thyroxin index was significantly greater in serum samples of hamsters sacrificed at 7 P.M. than at 7 A.M. (lights on at 6:30 A.M.). Serum taken at 7 P.M. had less unsaturated binding sites than serum taken at 7 A.M. No significant A.M. versus P.M. differences in free thyroxin index were found in blind hamsters, although blind hamsters had significantly lower T4 and FTI than controls. Placing melatonin in the drinking water at a dose of 80 μg/ml did not significantly influence hormone levels. The greatest difference in hormone concentrations between control and blinded hamsters was found in P.M. samples. Blind hamsters had FTIs that were 48% of P.M. controls. Pinealectomy prevented the effects of blinding on T4 levels and

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00191.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The nighttime rise in pineal melatonin levels can be blocked by administration of the β‐adrenergic receptor antagonist, propranolol, in both Syrian hamsters and rats. Although the administration of β‐adrenergic receptor agonists such as norepinephrine or isoproterenol stimulates pineal melatonin production in the rat, these drugs are without apparent effect on indole production in the Syrian hamster. To determine whether this lack of stimulatory effect in the Syrian hamster is characteristic of this species, a comparison of the effects of norepinephrine and isoproterenol on pineal serotonin N‐acetyltransferase activity and melatonin content was conducted. In contrast to their lack of effect in the Syrian hamster, norepinephrine and isoproterenol stimulated pineal serotonin N‐acetyltransferase activity and melatonin content in the Djungarian hamster. Hourly injection of norepinephrine during a continuation of light into the normal dark period stimulated increases in the activity of serotonin N‐acetyltransferase and melatonin content in the Djungarian hamster but was without effect on these pineal parameters in the Syr

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00192.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Adrenaline (A)‐ and noradrenaline (N)‐cells in juxtacortical and central areas of adrenal medullas of nonoperated, sham‐operated, and pinealectomized male rats (n = 125) were investigated by quantitative electron and light microscopy. Animals were killed at eight time points during a standardized 24‐h, light‐dark (12:12) cycle 14 d after surgery. Diameters of nucleoli (n = 9,600) and the nucleolar margination rate were studied chiefly by light microscopy.Major findings include the following: (1) Twenty‐four‐hour changes occurred in nucleolar diameters in adrenomedullary chromaffin cells in nonoperated animals, with the peak in the late dark phase (X ± SD, A‐cells: 1.29 $ 0.06 μm; N‐cells: 1.23 ± 0.05 μm) and the minimum in the mid‐light (A‐cells: 1.16 μ 0.04 μm) or early dark (N‐cells: 1.14 μ 0.03 μm) phase. (2) These changes were markedly dampened (diminished) in sham‐operated animals. (3) Since this dampening of time‐of‐day changes after sham‐operations was not seen in A‐cells after pinealectomy, mediation by the pineal gland of this dampening is suggested. (4) Pinealectomized animals showed 24‐h changes in nucleolar diameters, but these changes differed from those of nonoperated controls in their temporal and phase relations. For example, there was phase advance in A‐cells in the juxtacortical area and desynchronization in N‐cells. (5) Furthermore, rhythm amplitude was slightly increased in A‐cells and slightly decreased in N‐cells after pinealectomy. (6) A‐ and N‐cells differed from each other consistently and significantly in the quantitative morphology of their nuleoli and nuclei, and slightly in the patterns of their time‐of‐day changes in nucleolar size. (7) Nucleolar size usually showed a tendency for a regional gradient, decreasing slightly from periphery toward the center. These observations contribute to our understanding of the chronobiology and functional relations of adrenomedullary chromaffin cells, and of the e

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00193.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Several procedures known to influence pineal gland secretion were studied for their effects on the ventral prostate of rats. Stereological measurements were made of volume fractions of acini and glandular epithelium, surface fractions of glandular epithelium, and length fractions of acini. From these figures and the weights of the glands, the volumes, surface areas, and lengths of these features were calculated, as well as the mean epithelial heights, mean acinar diameters, and mean distances between glandular acini. None of these measurements differed in sham‐operated controls, pinealectomized, or blinded rats. In blind‐anosmic rats, however, there were significant decreases in the weights of the prostates and the volumes of the acini, reflecting significant decreases in the mean diameters of acini. None of the other parameters differed from those of controls, except the length fraction of acini. These results differ from those described by others following castration in rats, indicating that the action of the pineal gland on the ventral prostate may be different from that of androgen deprivation, in this species. Caution should therefore be exercised in the interpretation of the results of experiments in which prostate weights are used as indications of the actions of pineal hormones on the neuroendocrine‐gonadal

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00194.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

An ultrastructural stereological analysis was made of the nucleus in pinealocytes of 28 male Fischer rats sampled at seven times in a light:dark 12:12 photoperiod cycle. Comparisons of the data from the seven times, in relation to daily means, showed variations in mean nuclear cross‐sectional surface area of ±16%, and in mean nuclear perimeter of ±10%. Peaks in both nuclear dimensions occurred at the middle of the light period and were coincident with the presence of elaborate nuclear configurations and deep indentations. At 2330 and 0430 (1 and 6 h after lights off) nuclear folding was generally less complex. Mitochondria were found in close association with the nuclear folds. Forty percent of nucleoli were marginated at all of the sampling times, except at 1130 (l h after lights on) and at 2330 (l h after lights off), when 50% and 35%, respectively, were margina

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00195.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The role of the pineal gland in diet‐induced thermogenesis (DIT) and growth of brown adipose tissue (BAT) in rats during voluntary overfeeding was studied using pinealectomized and sham‐pinealectomized rats. Overfeeding was induced by offering the animals a cafeteria‐diet (CD) which contained a selection of highly palatable food items. Rats which were fed CD had significantly increased interscapular brown adipose tissue (IBAT) mass and increased tail‐skin temperature indicating the importance of the tail in thermoregulation during DIT. Pinealectomy had no effect on the increase in tail‐skin temperature and deposition of IBAT, which were stimulated by CD feeding. These findings suggest that the pineal is not directly involved in modulating the metabolism of BA

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00196.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Pineal weight and serotonin (5‐HT) and norepinephrine (NE) contents were studied in male Sprague‐Dawley rats that were maintained under controlled light:dark conditions (LD 14:10; lights on 0700‐2100) and that received daily subcutaneous injections of either melatonin (20 μg in 0.1 ml per animal) or the same volume (0.1 ml) of vehicle alone, at one of two times (0800‐0900 or 1800‐1900). Animals were sacrificied at four times (1000, 1400, 2000, or 2300) on the day after the last of the 7 consecutive d of injection. Pineal glands were quickly weighed and then frozen for 5‐HT and NE assay by the Maickel and Miller extraction and fluorescence methods.Pineal NE content showed differences related to time of day, in confirmation of early work. But no effects attributable specifically to melatonin were found. Melatonin also failed to affect pineal 5‐HT content significantly. But injection of either melatonin or vehicle at 1800‐1900 led to a reduction in 5‐HT content averaging 36% when sampled at either 2000 or 2300, and in comparison with animals injected at 0800‐0900. It is suggested that a stresslike or zeitgeberlike effect of injections within a critical period at the end of the daily light phase can cause an earlier‐than‐normal daily fal

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00197.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The pineal gland of rats 12–28 months old was studied with light and electron microscopes. All pineal components exhibited regressive changes of different intensity with age. In type I pinealocytes, there was a marked increase in dense bodies as well as the occasional appearance of wide cell profiles full of vesicles. Type II pinealocytes showed nuclear infoldings and cytoplasmic deposits of lipofuscin. Pineal stroma displayed an increase in connective tissue fibers, both collagen and oxytalan, as well as remains of basement membranes and other materials of unknown nature. Calcareous concretions were also found, mostly in the pineal capsule. All regressive changes were more intense with increasing ag

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00198.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY