Spermiogenesis in hibernating golden hamsters

Zusammenfassung Während einer Periode von Dezember bis März wurden von Goldhamstern im Winterschlaf und gleichzeitig von Kontrolltieren, die bei Zimmertemperatur gehalten wurden, die linken Testes untersucht. Aus der Korrelation zwischen dem histologischen Bild und dem relativen Organgewicht ging hervor, dass der Winterschlaf keinen Einfluss auf die Proliferation der Zellen des Keimepithels hat, dass sie aber die Differenzierung dieser Zellen verzögert.     

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

Summary Golden hamsters with spontaneous hypercholesterolemia at 22°C developed a further increase in plasma cholesterol when they were maintained at 6°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.     

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.     

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.     

Daily melatonin injections inhibit short-day-induced testicular regression in hamsters

Summary Daily injections of melatonin were found to retard testicular regression in hamsters exposed to LD 10:14, if the injections occurred in the morning (i.e., 0.5 h after lights on), but not if they occurred in the afternoon (i.e., 6 h after lights on). These results indicate that appropriately timed injections of melatonin can at least partially block the inhibitory effects of short days on gonadal activity in the photoperiodic hamster.We wish to thank Susan Losee and Susan Stice for excellent technical assistance and Gary Ellis for his comments. This investigation was supported by NIH grants HD-09885, HD 12622 and Research Career Development Award HD-00249 (F. W. T.) from the National Institute of Child Health and Human Development.     

Cardiac output and regional blood flow studies in golden hamsters

Summary A method is described for the acute catheterization of the left ventricle of the heart and descending aorta combined with the use of the radioactive microsphere technique to study hemodynamic parameters in anaesthetized hamsters. The hemodynamic parameters studied include mean blood pressure, cardiac output, percentage distribution of cardiac output and regional blood flows in different organs.     

Profound hypothermia in golden hamsters (Mesocricetus auratus) induced by serotonergic potentiating and noradrenergic inhibiting drugs

Profound hypothermia (6 degrees C) was induced in cold exposed golden hamsters (Mesocricetus auratus) by a combination of drugs that potentiate brain serotonergic activity (fluoxetine and pargyline) and inhibit noradrenergic activity (alpha-methyl-p-tyrosine). Individual drugs and combinations of 2 were ineffective.     

Profound hypothermia in golden hamsters (Mesocricetus auratus) induced by serotonergic potentiating and noradrenergic inhibiting drugs

Summary Profound hypothermia (6°C) was induced in cold exposed golden hamsters (Mesocricetus auratus) by a combination of drugs that potentiate brain serotonergic activity (fluoxetine and pargyline) and inhibit noradrenergic activity (alpha-methyl-p-tyrosine). Individual drugs and combinations of 2 were ineffective.Acknowledgements. We acknowledge the support of a research grant PCM74-05158 A01 to A.H.M. from the National Science Foundation (USA) and thank Lilly Research Laboratories, Indianapolis, Indiana, for the gift of fluoxetine (Lilly 110140).     

Failure of the pineal removal to prevent some cold-induced testicular changes in golden hamsters

Résumé La diminution du poids des testicules et l'arrêt de la spermatogenèse furent observés chez des hamsters exposés au froid et maintenus dans un cycle alternant de 14 h de lumière et 10 h d'obscurité. En enlevant la glande pinéale, ces changements organiques ne se sont pas produits.     

DNA synthesis in exocrine and endocrine pancreas after partial hepatectomy in Syrian golden hamsters

Summary ³H-thymidine autoradiography showed an enhanced DNA synthesis, in acinar and islet cells of pancreas after partial hepatectomy in syrian golden hamsters. A significant nuclear labeling index of acinar cells was observed between 48 and 84 h and reached control levels by 120 h. An increased labeling index of islet cells was also observed, however, this increase was not statistically significant. These results indicate growth factor(s) produced after partial hepatectomy is capable of inducing DNA synthesis in pancreas.This work is supported by NIH grant CA 36043.     

Body weight and organ sizes in warmth-adapted and in cold-adapted,hibernating golden hamsters

Zusammenfassung Von Dezember bis März wurden bei Goldhamstern im Winterschlaf und gleichzeitig bei wachen Kontrolltieren, die bei Zimmertemperatur gehalten wurden, Veränderungen von Organgewichten untersucht. Eine signifikante Zunahme des Gewichtes wurde bei Leber, Nieren, Herz, Pankreas, braunem Fettgewebe, Milz, Nebennieren und Nebennierenrinde der. Winterschläfer gefunden. Bei Körpergewicht, Haut, Testes, Femora und Nebennierenmark waren keine Unterschiede zwischen beiden Tiergruppen festzustellen.     

DNA synthesis in exocrine and endocrine pancreas after partial hepatectomy in Syrian golden hamsters

3H-thymidine autoradiography showed an enhanced DNA synthesis in acinar and islet cells of pancreas after partial hepatectomy in syrian golden hamsters. A significant nuclear labeling index of acinar cells was observed between 48 and 84 h and reached control levels by 120 h. An increased labeling index of islet cells was also observed, however, this increase was not statistically significant. These results indicate growth factor(s) produced after partial hepatectomy is capable of inducing DNA synthesis in pancreas.     

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.     

Complete development ofAncylostoma ceylanicum (Looss, 1911) in golden hamsters,Mesocricetus auratus

Zusammenfassung Es gelang, den HakenwurmAncylostoma ceylanicum an den Goldhamster zu adaptieren, was zur Vereinfachung chemotherapeutischer Versuche bei der Bekämpfung dieses tierischen und menschlichen Parasiten im Laboratorium beitrug.     

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.