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Biomedical subjects

E Damian

Publications and source records attributed to E Damian.

At least 73 records · Page 4Linked to original sources
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Effect of pineal treatment on serum and testicular sialic and nucleic acids in basal and HCG treated rats.

The effect of a melatonin-free pineal extract, two pineal fractions, obtained by ultrafiltration one above, the other under 10,000 daltons molecular weight, melatonin and the partly purified gonadotropin inhibiting urinary substance (GIS) on the serum and testicular sialic acid, testicular nucleic acids and proteins in the rat under basal conditions and after stimulation with exogeonus HCG, was investigated. Under basal condition the pineal extract induced a statistically significant decrease in serum and testicular sialic acid after 3 and 12 days of treatment. The effect of the extract on the sialic acid was also present under the action of the two fractions after a 12-day treatment. Conversely, after a 30-day treatment the pineal extract induced an opposite effect, i.e. a statistically significant increase in the serum and testicular sialic acid. Melatonin failed to induce any significant changes after a 3-day trial. GIS induced an increase only in serum sialic acid after a 6-day trial. Under exogenous HCG stimulation the following results were obtained: doses of HCG (25,50 and 75 i.u.) given along 3 days caused a significant increase in sialic acid; the pineal extract inhibited only partly the stimulating effect of HCG on the sialic acid; melatonin did not produce comparable effects and GIS caused an elevation only at serum level. As concerns the nucleic acids and proteins, under basal conditions the pineal extract caused the following effects: a significant increase in RNA and proteins after 3 days, a slightly increased level after 12 days and a significant decrease after 30 days of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

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Effect of melatonin-free pineal extract on prolactin in castrated and thyrotropin releasing hormone-stimulated rats.

Administration of a melatonin-free pineal extract to the rat induced the following effects on prolactin: a) under basal conditions, after 4 hrs from a single injection or after 3 days of treatment, there was a decrease of 34% and 28% respectively, in serum prolactin, with no change in the pituitary content of this hormone; b) when prolactin was stimulated by castration the decrease of the serum level of this hormone (-37%) was accompanied by a decrease in its pituitary content (-33%) and concentration (-35%); c) under conditions of exogenous TRH stimulation the decrease in serum prolactin (-26%) was accompanied by a decrease in pituitary prolactin content (-27%) and concentration (-21%), the latter two without statistical significance. The role of the pineal gland on prolactin is discussed.

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Effect of melatonin-free pineal extract on cholesterol in basal and HCG treated rats.

The effect of a melatonin-free pineal extract on total, free and esterified testicular and serum cholesterol in the rat under basal conditions and after stimulation with exogenous HCG was followed up. Administration of a 2 ml daily dose from this extract to the rat under basal conditions along 3, 12 and 30 days reduced the esterified fraction of testicular cholesterol, more markedly in the 12-day experiment. The total free and esterified serum cholesterol also diminished significantly in the 3 and 12-day experiments. Under HCG stimulation the pineal extract inhibited the lowering effect of HCG on the esterified fraction in the testis and on the free and esterified fraction at serum level. Under both these experimental conditions, the pineal extract affected the esterified cholesterol at testicular level, a fraction used in androgen hormones production, and the free and esterified serum cholesterol. The auhors comment on the inhibiting role of the pineal extract exerted on testicular synthesis of cholesterol and testosterone under basal conditions as well as the regulating role of the pineal gland under conditions of exogenous HCG stimulation.

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Reduction of serum and testicular sialic acid by melatonin-free pineal extract in rats.

The effect of a melatonin-free pineal extract on sialic acid in the rat was studied. Administration of 2 ml extract/day/animal for 3 and 12 days induced the following effects: a) a statistically significant decrease in testicular concentration and content of sialic acid after 3 days (by 14 and 16% respectively) and b) a statistically significant decrease both in testicular concentration and content and serum level of sialic acid after 12 days (by 13, 12 and 9% respectively). The involvement of the pineal extract in the synthesis and secretion of testicular sialic acid is discussed.

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Inhibition of HCG induced testosterone increase by melatonin-free pineal extract in the rat.

The effect of a pineal treatment on rat testosterone under conditions of exogenous HCG stimulation was followed-up. Administration of 2 ml/day/animal of a melatonin-free pineal extract for 3 days lowered by 23% (p less than 0.01) the serum level and by 32% (p less than 0.02) the testis content in testosterone, both values being increased by concomitant administration of 50 UI HCG per animal. In other words, the melatonin-free pineal extract inhibited partially the testis response to HCG. The antiandrogenic action of the pineal extract is discussed.

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Antigonadotropic activity of two fractions of melatonin-free pineal extract separated by ultrafiltration.

Using the mouse uterus weight test and the rat ventral prostate weight test in basal conditions and under exogenous stimulation, the activity of 2 fractions of molecular weight above and under 10,000 daltons obtained by ultrafiltration of a melatonin-free pineal extract was tested against a total pineal extract and the same extract subjected to dialysis. The results showed that the larger fraction is predominantly anti-LH whereas the smaller fraction is anti-FSH. The antigonadotropic activity of the total and partially purified pineal extract against the effects of pineal melatonin and arginine-vasotocin is discussed.

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Inhibition of pituitary-testicular axis response to gonadotropin releasing hormone by pineal treatment.

Purification by ultrafiltration of the pineal extract with antigonadotropic activity enabled us to obtain two fractions, one above 10,000 daltons molecular weight and one below. Administration of these two fractions to intact or castrated rats showed a dissociation of their activity, namely, the larger fraction proved to be anti-LH and the smaller one anti-FSH, as also demonstrated by the specific biologic tests of these hormones. Pineal pre-treatment of the intact and castrated rats whose pituitary had been stimulated with gonadotropic releasing hormone (GnRH) showed that both fractions lower significantly LH and FSH serum levels in both groups of animals. The pineal treatment inhibited the pituitary response to GnRH both in the intact and castrated animals.

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Inhibition of pituitary response to gonadotropin releasing hormone by urinary gonadotropin inhibiting substance.

The effect of the partially purified urinary gonadotropin inhibiting substance (GIS) on pituitary response to stimulation with gonadotropin releasing hormone (GnRH) was studied. The biologic control of the purified substance showed that the anti-LH and anti-FSH activity of the crude urinary substance was preserved. The experiments made on intact and castrated rats previously treated for two days with GIS and stimulated with GnRH revealed that this substance caused a significant decrease in the serum level of LH and FSH but not in their pituitary content. Furthermore it lowered serum and testicular testosterone in the intact lot as against the controls. The mechanism of action of the purified urinary substance on the pituitary-testicular axis is discussed.

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Studies on melatonin-free pineal extract.

This paper offers the data accumulated in time, on preparation, partial purification, physico-chemical and biologic characterization of the melatonin-free pineal extract. Purification by ultrafiltration of the extract obtained from bovine pineal yielded two fractions: one above and one below 10,000 daltons. Administration of these two fractions in parallel with total pineal extracts, to the rat caused a fall in the serum LH and FSH levels in basal conditions and under endogenous or exogenous stimulation with gonadotropin releasing hormone, with a consecutive fall in testosterone. The results obtained by RIA, of LH, FSH and testosterone were also supported by the specific biologic tests for LH and FSH. The intervention of the pineal in the pituitary-gonadal axis as well as the chemical nature of the pineal antigonadotropic factors are discussed.

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Effect of urinary gonadotropin-inhibiting substance on rat prolactin.

Administration of the partially purified urinary gonadotropin inhibiting substance (GIS) to the rat induced the following effects on prolactin: a) under basal conditions, 4 hrs after a single dose, or after 3 days of treatment, serum prolactin decreased by 36%, 35% respectively (p less than 0.05) and was associated with a nonsignificant decrease in pituitary content and concentration of this substance; b) under endogenous stimulation (castration) the 49% (p less than 0.05) decrease in serum prolactin was associated with a decrease to the limit of statistical significance of its pituitary content and concentration; c) under exogenous stimulation with TRH, the significant decrease in serum prolactin was associated with a nonsignificant decrease in its pituitary content and concentration. The action of lowering prolactin serum in relation to the similar effect of the pineal extract is discussed with reference to the possible pineal origin of GIS.

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The effect of pineal polypeptides and melatonin on serum and pituitary LH and FSH in adult male rats.

The effect of a pineal polypeptide extract was tested against the effect of melatonin on the serum level and pituitary concentration of LH and FSH of the adult male rat both in basal conditions and in response to exogenous (GnRH) and endogenous (castration) stimulation. A 2 ml dose of pineal polypeptides per injection caused a signifcant fall in serum LH and FSH both in the intact, the intact + GnRH, and the castrated animals. The decrease in pituitary concentration of LH and FSH was of statistical significance only in stimulation conditions. A 50 micrograms dose of melatonn/injection failed to produce comparable effects. The antigondaotropic action of the biologically active pineal compounds is discussed.

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The effect of pineal treatment and pinealectomy on prolactin in rats.

Administration of melatonin-free pineal extract in doses of 2 ml/day/animal along 3 or 7 days caused a statistically significant decrease in the rat serum prolactin level by 28 and 25% respectively, as against the controls. Pinealectomy caused a statistically significant increase in the serum prolactin level by 34% as against the intact controls and by 30% as against the sham-operated ones. The authors discuss their completely oposite results and the role of the pineal gland on prolactin.

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Inhibitory action of pineal extract on LH and FSH.

The influence of melatonin-free pineal extract on luteinizing hormone (LH) and follicle-stimulating hormone (FSH) was studied. Administration of bovine pineal extract in intact rats was found to induce a statistically significant decrease of serum LH and FSH. The pineal extract also inhibited the 24-hour-post-castration rise of serum and pituitary LH and FSH in mature male rats. The stimulating effect of gonadotropin-releasing hormone (GnRH) on pituitary LH and FSH was also inhibited in intact animals. The antigonadotropic activity of melatonin-free pineal extract, melatonin and arginine-vasotocin (AVT) is discussed.

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