The effects of dopaminergic blocking agents on the glucose tolerance test in 6 humans and 6 dogs.

Pre-treatment with low doses of sulpiride, an atypical dopaminergic blocking agent, but not haloperidol, a classical dopaminergic blocking agent, decreased tolerance to glucose and increased blood serotonin levels in 6 normal humans and 6 normal dogs investigated.     

Prolactin and growth hormone releasing activity of [D-Met2, Pro5]-enkephalinamide in the rat after systemic administration

Summary The growth hormone (GH) and prolactin releasing (PRL) activity of [D-Met², Pro⁵]-enkephalinamide (EKNH₂), an opioid peptide analog with higher opiate agonist activity that morphine, was compared in the unanesthetized male rat to those of equimolar doses of morphine upon systemic injection. EKNH₂ proved to be a higher PRL, but not GH, releaser than the opiate alkaloid.     

Evidence of 5 alpha-androstane-3 beta, 6 alpha, 17 beta-triol and of 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol in the anterior pituitary of the prepuberal male rate]

Incubation of 3H-5 alpha-androstane-3 beta, 17 beta-diol with anterior pituitaries from immature male Rats led to the major production of polar radio-metabolites. Of these, 53 and 27% were identified with 5 alpha-androstane-3 beta, 6 alpha, 17 beta-triol and 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol, respectively. The formation of these trihydroxysteroids may be involved in the intracellular regulation of 5 alpha-androstane-3 beta, 17 beta-diol levels.     

Inhibitory effects of LHRH on LH receptors in the rat testis]

A single injection of LHRH to the adult male rat, as of its analog [D-Ala6, des-Gly-NH102] LHRH ethylamide, resulted in a marked decrease in LH receptors in the tests. Plasma testosterone level and the weight of the seminal vesicles and prostate were also decreased after treatment. These data demonstrate that LHRH can decrease the sensitivity of LH receptors and testicular function in the rat.     

Influence of testicular fluid, spermatozoa and androgens on physiological activity of rat epididymis]

By ligation of the efferent duct and the corpus epididymis, the GPC concentration in this delimited anterior region decreased. However, HCG infection increased the GPC concentration. When spermatozoa are present in the epididymal tubule there is always a decrease in GPC concentration in these experimental conditions. Activity of the epididymis is disturbed by ligation.     

Opposite effects of one and three injections of cortisone or thyroxine on intestinal lactase activity in suckling mice

Summary A single injection of cortisone or thyroxine to 8-day-old suckling mice initiates a temporary decrease of lactase activity. On the contrary, 3 injections of cortisone or thyroxine provoke a significant increase of lactase activity. It appears that the mechanism which controls the postnatal development of lactase in suckling animals is more complex than expected.Supported by grant MA-5969 from the Medical Research Council of Canada to D. M. C. M. is a recipient of a studentship from MRC of Canada.     

Opposite effects of one and three injections of cortisone or thyroxine on intestinal lactase activity in suckling mice.

A single injection of cortisone or thyroxine to 8-day-old suckling mice initiates a temporary decrease of lactase activity. On the contrary, 3 injections of cortisone or thyroxine provoke a significant increase of lactase activity. It appears that the mechanism which controls the postnatal development of lactase in suckling animals is more complex than expected.     

Effect of 5-thio-D-glucose on blood glucose and glucose-6-phosphatase activity in mice

Summary Blood glucose was significantly elevated by 5-thio-D-glucose administration (25, 50, and 100 mg/kg). The ratelimiting enzyme glucose-6-phosphatase of liver was also increased. The elevation of blood glucose was due to the rapid glycogenolysis of liver.Acknowledgments. We are thankful to Mr T. Natarajan, Department of Biochemistry for ministerial assistance.     

7-alpha-Hydroxylation of 5 alpha-androstane-3 beta, 17 beta-diol in human normal and hyperplastic prostates]

Incubation of 4-14C-5 alpha-androstane-3 beta, 17 beta-diol with human normal and hyperplastic prostate minces led to the NADPH-dependent production of a major polar radiometabolite which was identified as 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol and proved the presence of a 3 beta-hydroxysteroid-7 alpha-hydroxylase in prostate. Such evidences may bring new leads for the study of the mechanisms of androgenic steroid action in the prostate gland.     

7 alpha-Hydroxylation of 5 alpha-androstane-3 beta, 17 beta-diol in normal and hyperplastic human prostate]

Incubation of 4-14C-5 alpha-androstane-3 beta, 17 beta-diol with human normal and hyperplastic prostate minces led to the NADPH-dependent production of a major polar radiometabolite which was identified as 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol and proved the presence of a 3 beta-hydroxysteroid-7 alpha-hydroxylase in prostate. Such evidences may bring new leads for the study of the mechanisms of androgenic steroid action in the prostate gland.     

Differential effects of prostaglandins and isoproterenol on cAMP content and Na,K pump activity in rat submandibular acini

Summary The -adrenergic agonist isoproterenol and prostaglandins E₁ and E₂ (but not F₂) increased the cAMP content of rat submandibular acini in vitro, but only isoproterenol enhanced ouabain-sensitive⁸⁶Rb (K) uptake. These findings suggest that cAMP is not involved in the activation of the Na, K pump in salivary cells.     

Differential effects of prostaglandins and isoproterenol on cAMP content and Na, K pump activity in rat submandibular acini

The beta-adrenergic agonist isoproterenol and prostaglandins E1 and E2 (but not F2 alpha) increased the cAMP content of rat submandibular acini in vitro, but only isoproterenol enhanced ouabain-sensitive 86Rb (K) uptake. These findings suggest that cAMP is not involved in the activation of the Na, K pump in salivary cells.