Growth of fetal organs after maternal partial hepatectomy or unilateral nephrectomy

Résumé Après hépatectomie partielle ou néphrectomie unilatérale pratiquées chez les rates portante, quelquesuns des organes ftaux ont été pesés. Quelques jours après l'opération, on a constaté une inhibition de la croissance des organes ftaux correspondants. Des rates gravides ayant subi une laparotomie ont servi de témoins.     

Growth hormone signal transduction

Growth hormone (GH) promotes animal growth by stimulating bone and cartilage cell proliferation, and influences carbohydrate and lipid metabolism. Some of these effects are brought about indirectly via somatomedin induction in hepatocytes, others by acting directly on the target cells. In either case, GH first binds to specific receptors on cells to trigger a sequence of biochemical events culminating in a biological response. Recently much has been learnt about the molecular structure of GH receptor, its binding to ligand, and the ensuing signal transduction events.     

Growth hormone resynthesis in the pituitary after depletion induced by a hypothalamic extract

Riassunto Lo studio della velocità di resintesi dell'ormone somatotropo nella ipofisi di ratto dopo la massiva deplezione indotta dalla somministrazione endocarotidea di un estratto di eminenza mediana dell'ipotalamo, ha messo in evidenza che 1 ora dopo la somministrazione il contenuto dell'ormone viene ricostituito in misura del 60%, 3 ore dopo sale all'80%, 5 ore dopo corrisponde ai valori normali.     

Metabolic restoration in rat liver after partial hepatectomy

Zusammenfassung Es zeigt sich während des frühen Regenerationsstadiums bei der teilweise hepatektomierten Rattenleber, dass ein Anstieg im Galaktose-Metabolismus mit gleichzeitiger Abnahme seiner Hemmung durch Ethanol einhergeht. Nach vollständiger Geweberegeneration kehrt der normale Metabolismus zurück.

---

---

I wish to thank ProfessorJ. H. Quastel for providing me with the facilities and for his encouragement during my work at McGill University, Montreal (Canada).     

Antidiuretic hormone involvement in the release of alpha-melanocyte-stimulating hormone by hyperosmotic stimuli

In the normal Wistar rat, the plasma alpha-MSH level was raised by hypertonic saline injection (as compared with control rats injected with isotonic saline). No such rise in alpha-MSH followed hypertonic saline administration in the Brattleboro (hereditary diabetes insipidus) animal (compared to isotonic saline injected controls). It is suggested that, in the rat, endogenous antidiuretic hormone is involved in the secretory response of the pars intermedia to osmotic stimuli.     

Somatostatin inhibits in vitro release of luteinizing hormone releasing hormone from rat mediobasal hypothalamic slices

Summary Somatostatin, in concentrations ranging from 10^–10 M to 10^–7 M, induces a dose-dependent inhibition of LHRH release from mediobasal hypothalamic slices incubated in vitro. In contrast, VIP, secretin, glucagon, substance P, neurotensin and arginine-vasotocin do not affect spontaneous release of LHRH.     

Effect of thyroid hormone on somatomedin-C release from perfused rat liver

The effect of thyroid hormone on plasma somatomedin-C (SmC) level and on SmC release from perfused rat liver was investigated. Plasma SmC levels and liver tissue SmC were significantly increased in thyroxine-treated rats. Physiological doses of triiodothyronine increased SmC release and SmC concentration in the perfused rat liver. These results indicate that thyroid hormone directly enhances the synthesis and release of SmC in the rat.     

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.     

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.     

Hepatic regeneration in the rat after subtotal (90%) hepatectomy treated with testosterone

A single dose (120 mg/kg IM) of testosterone administered 1 month before subtotal hepatectomy (90%) in Rats, reduced liver steatosis and allowed complete liver regeneration.     

Succinoxidase activity of mitochondria isolated from the liver of rats after partial hepatectomy and hypophysectomy

Zusammenfassung Bei den 24 und 48 h nach partieller Hepatektomie (Resektion von 65–70% der Leber) aus der Rattenleber isolierten Mitochondrien wurde eine Abnahme der sukzinoxydaseaktivität beobachtet. Dasselbe wurde auch bei Ratten beobachtet, bei welchen gleichzeitig mit der partiellen Hepatektomie eine Hypophysektomie durchgeführt wurde. Die Veränderung der Sukzinoxydaseaktivität ist nicht auf eine Erniedrigung der Mitochondrienzahl pro Gewichtseinheit Leber zurückzuführen.     

Hepatic DNA synthesis after partial hepatectomy in rats treated with protamin-Zn-insulin under different nutritional conditions

Zusammenfassung Bei Ratten mit dauerndem Zutritt zur Nahrung wurde die Zunahme der Desoxyribonukleinsäure-Synthese in der Leber (60–70% Hepatektomie) durch Applikation von Protamin-Zn-Insulin (3 IE/100 g Körpergewicht) s.c. 1h vor Hepatektomie stimuliert. Im Gegensatz dazu wurde bei Ratten mit einem stimulierten postoperativen Zutritt zur Nahrung die Synthese der Desoxyribonukleinsäure im Lebergewebe nach partieller Hepatektomie mit Protamin-Zn-Insulin gehemmt.     

Liver regeneration after partial hepatectomy in rats exposed before the operation to the stress stimulus

Zusammenfassung Es wird nachgewiesen, dass bei Ratten, die 8 h vor partieller Hepatektomie einer Stress-Stimulation ausgesetzt wurden, die Intensität der DNS-Synthese postoperativ im Vergleich mit den Kontrolltieren grösser war. Ebenso waren Veränderungen des Lebergewichtes und des Triglyzeridinhaltes in der Leber nach der partiellen Hepatektomie dieser Ratten stärker ausgeprägt. Vergleichbare Resultate wurden auch bei Ratten gefunden, die in der gleichen Zeit vor der partiellen Hepatekto'mie eine ACTH-Injektion erhielten.     

Post nephrectomy increase in serum ribonuclease activity after total hepatectomy or nitrogen mustard derivatives administration

Résumé L'augmentation de l'activité de la ribonucléase du sérum, qui fait suite à la néphrectomie bilaterale chez le rat n'est pas modifiée par une évisceration préalable avec hépatectomie totale ou administration de moutardes azotées. Ces résultats indiquent que ni le foie ni les leucocytes et organes hémopoiétiques ne peuvent être considerés comme sources exclusives de cette augmentation.

---

---

Aided by grants from Conselho Nacional de Pesquisas and The Rockefeller Foundation.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Summary Continuous administration of leukotriene C₄ (LTC₄, 10^–10 M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10^–9 M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC₄ did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC₄ (10^–10 M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC₄ on LH exocytosis.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Continuous administration of leukotriene C4 (LTC4, 10(-10) M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10(-9) M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC4 did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC4 (10(-10) M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC4 on LH exocytosis.     

Inhibition of TSH-stimulated thyroid hormone release and potentiation of TRH-stimulated TSH release by indomethacin in perifusion systems of rat thyroids and pituitaries

Summary Using indomethacin (Ind), a prostaglandin, synthesis inhibitor, in vivo experiments in rats and in vitro experiments with perifusion systems of rat thyroids and pituitaries were conducted. After 35 days of intragastric infusion of Ind, serum TSH levels were markedly increased, the thyroid was swollen and, as a consequence, T₃ and T₄ levels were normal. The T₃ release from perifused rat thyroids under continuous stimulation with 10 mU/ml TSH was inhibited significantly (p<0.01) by 1.0×10^–6 M Ind. On the other hand, the TSH release from perifused rat pituitaries under TRH stimulation was enhanced conspicuously by Ind. It was concluded that Ind decelerated thyroid hormone release from the thyroid and accelerated TSH release from the pituitary in perifusion systems.     

Inhibition of TSH-stimulated thyroid hormone release and potentiation of TRH-stimulated TSH release by indomethacin in perifusion systems of rat thyroids and pituitaries

Using indomethacin (Ind), a prostaglandin synthesis inhibitor, in vivo experiments in rats and in vitro experiments with perifusion systems of rat thyroids and pituitaries were conducted. After 35 days of intragastric infusion of Ind, serum TSH levels were markedly increased, the thyroid was swollen and, as a consequence, T3 and T4 levels were normal. The T3 release from perifused rat thyroids under continuous stimulation with 10 mU/ml TSH was inhibited significantly (p less than 0.01) by 1.0 X 10(-6) M Ind. On the other hand, the TSH release from perifused rat pituitaries under TRH stimulation was enhanced conspicuously by Ind. It was concluded that Ind decelerated thyroid hormone release from the thyroid and accelerated TSH release from the pituitary in perifusion systems.