Marked elevation of HDL-cholesterol in cold-adapted golden hamsters

Golden hamsters with spontaneous hypercholesterolemia at 22 degrees C developed a further increase in plasma cholesterol when they were maintained at 6 degrees C. This hypercholesterolemia was associated with a redistribution of plasma cholesterol between VLDL and HDL. Plasma cholesterol transported in the VLDL decreased while cholesterol in the HDL increased by 45%. The LDL profile was not significantly modified.     

Peripheral sympathetic innervation of the deep pineal gland of the golden hamster

Summary Both the superficial and deep pineal components of the intact hamster contain a rich network of green to yellow-green fluorescent nerve fibres. After either superior cervical ganglionectomy or after transection of the nervi conarii the majority of the fluorescing fibres disappeared from both the superficial and deep pineal mases. Although the deep pineal remained intact after surgical removal of the superficial pineal, it was devoid of any green or yellowgreen fluorescent fibres.Supported by NSF Grant No. BMS74-06275A01     

Pineal inhibition of compensatory testicular enlargement in light-deprived hamsters

Zusammenfassung Halbseitige Kastration fÜhrt bei geblendeten Goldhamstermännchen mit Atrophie der Geschlechtsorgane nur nach Pinealektomie zu kompensatorischer Hodenhypertrophie.

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Supported by grant No. HD-02937 United States Public Health Service.

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U.S.P.H.S. Career Development Awardee (No. 1 K04 HD42398).     

Maturation of the pineal melatonin rhythm in long- and short-day reared Djungarian hamsters

Male Djungarian hamsters, reared under long (16L/8D) or short (10L/14D) days, were sacrificed at various ages during the day or night, or at night following a 30-min light pulse. The pineal melatonin rhythm matured similarly under long and short days by 20 days of age. The results are discussed in context of the hypothesis that melatonin mediates the photoperiod effects which forestall puberty in short-day reared hamsters.     

Maturation of the pineal melatonin rhythm in long- and short-day reared Djungarian hamsters

Summary Male Djungarian hamsters, reared under long (16L/8D) or short (10L/14D) days, were sacrificed at various ages during the day or night, or at night following a 30-min light pulse. The pineal melatonin rhythm matured similarly under long and short days by 20 days of age. The results are discussed in context of the hypothesis that melatonin mediates the photoperiod effects which forestall puberty in short-day reared hamsters.Supported by NIH research grant HD-05481.     

Induction of neurosarcoma by injections of N-nitrosobutylurea in suckling syrian golden hamsters

Zusammenfassung Durch Injektion von N-Nitrosobutylharnstoff in junge Goldhamster wurden in über 50% der Versuchstiere Neurosarkome erzeugt.     

Role of acoustic stress on the development of polyoma tumors in immunized golden hamsters]

An acoustic stress increases the metastatic spread of polyoma virus-induced tumors in syrian Hamsters. To try to elucidate the mechanism of this action, we studied the effect of stress on the protection afforded by the virus against tumour challenge. Exposure to ultrasonics during the immunization period markedly decreased the protective effect of the virus.     

Effect of removal of the Harderian glands on pineal melatonin concentrations in the Syrian hamster

Summary Peak melatonin levels which are normally present in male Syrian hamsters at 8 h after the onset of darkness in animals maintained under a lightdark cycle of 1410, were significantly decreased following the removal of the Harderian glands.Supported by NSF grant PCM 77-05734.     

Effect of photoperiod on early changes in the neonatal rat pineal gland

Summary It is concluded that photoperiod has little direct effect on the mitotic activity or morphological development of the pineal parenchymal cell of the rat in the early postnatal period.     

Effect of removal of the Harderian glands on pineal melatonin concentrations in the Syrian hamster.

Peak melatonin levels which are normally present in male Syrian hamsters at 8 h after the onset of darkness in animals maintained under a light:dark cycle of 14:10, were significantly decreased following the removal of the Harderian glands.     

Single injections of triazolam,a short-acting benzodiazepine,lengthen the period of the circadian activity rhythm in golden hamsters

Single injections of the benzodiazepine, triazolam, induce phase shifts and cause a lengthening of the circadian activity rhythm in the golden hamster. The effect of triazolam on period depends on the phase of injection, but is not dependent on the direction of the phase shifts. Triazolam injections caused increases in period that were associated with phase advances as well as phase delays in the activity rhythm. This relationship between triazolam-induced phase shifts and changes in period is different from the relationship between light-induced phase shifts and period changes.     

Single injections of triazolam, a short-acting benzodiazepine, lengthen the period of the circadian activity rhythm in golden hamsters

Single injections of the benzodiazepine, triazolam, induce phase shifts and cause a lengthening of the circadian activity rhythm in the golden hamster. The effect of triazolam on period depends on the phase of injection, but is not dependent on the direction of the phase shifts. Triazolam injections caused increases in period that were associated with phase advances as well as phase delays in the activity rhythm. This relationship between triazolam-induced phase shifts and changes in period is different from the relationship between light-induced phase shifts and period changes.     

Morphological changes in the pineal gland of the albino rat by hypophysectomy and ovariectomy

Zusammenfassung Die dunklen Pinealzellen waren nach Hypophysektomie beträchtlich vermehrt, während die Vesikeln in den sympathischen Nervenendigungen vermindert waren. Auch nach Ovariektomie waren die dunklen Pinealzellen in geringerem Ausmass vermehrt, ohne dass die Vesikeln vermindert waren. Die osmiophile Granula war sehr spärlich.     

Failure of the pineal body of two species of birds (Coturnix coturnix japonica andPasser domesticus) to show electrical responses to illumination

Résumé Dans l'épiphyse de 2 espèces d'oiseaux il n'a pas été possible de démontrer une relation entre le potentiel électrique et les variations d'illumination. On peut en conclure que chez ces oiseaux l'épiphyse n'est pas un photorécepteur dans le sens conventionnel.

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This investigation was supported by National Science Foundation Grant No. GB-5605.     

Carcinogenic activation of benzo(a)pyrene by iodine and ferric chloride in the respiratory tract of Syrian golden hamsters

Summary Benzo(a)pyrene (0.5 mg), in itself weakly carcinogenic, when given in combination with ferric chloride (0,16 mg) or iodine (0,2 mg), alone noncarcinogenic, induced a number of tumors of different parts of the respiratory tract of Syrian golden hamsters.Partially supported by Public Health Service contracts PHS 43-68-959 and NO1 CP33278 from the Division of Cancer Cause and Prevention. The authors wish to thank Mrs Virginia Ooten for her technical assistance.     

Aromatization of androgens to estrogens by the rat pineal gland

Résumé Des homogénats de glande pineale de rat mâle métabolisèrent de la testostérone-C¹⁴ in vitro en stradiol-C¹⁴ et en strone-C¹⁴. Les métabolites furent identifiés chiomatographiquement et dans le cas de l'stradiol par recristallisation à activité spécifique constante. La conversion de la testostérone en stradiol fut de 0.19–0.27% et en strone de 0.02–0.04%. Ces résultatsci indiquent que la pinéale ressemble à d'autres régions du cerveau soumises au contrôle de la sécrétion de gonadotropines.

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These studies were supported by grants from the Comisión Nacional de Estudios Geo-Heliofísicos, Argentina and the World Health Organization. D.P.C. and C.A.N. are established investigators of the Comisión Nacional de Estudios Geo-Heliofísicos. J.M.R. is an established investigator of the Consejo Nacional de Investigaciones Cientificas y Técnicas, Argentina.