Reduction of pituitary nucleic acids, proteins, LH and FSH by melatonin-free pineal extract in rats stimulated with gonadotropin releasing hormone

The effect of a pineal treatment on the pituitary gland under exogenous stimulation with gonadotropin releasing hormone (GnRH) was assessed in the rat. A pretreatment with melatonin-free pineal extract under the above conditions caused a statistically significant decrease in the pituitary concentrations of DNA--by 21%, RNA--by 28%, proteins--by 19%, LH--by 25% and FSH--by 22%. Authors' findings show that the melatonin-free pineal extract plays a role in the metabolism of nucleic acids and pituitary proteins besides being implied in the synthesis of gonadotropic hormones.

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.

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.

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.

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.

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.

Purification and characterization of the antigonadotropic pineal substance

Purification by ultrafiltration of the melatonin-free pineal extract proved to have an antigonadotropic activity enabled the authors to obtain two fractions: one with a molecular weight above 10,000 and a second one with a molecular weight under 10,000 daltons. A biologic trial made by applying the mouse uterus weight test showed that both fractions inhibited the stimulating effect of exogenous HCG on the uterus. Ventral prostate weight test applied to rats showed that only the fraction above 10,000 daltons lowered the weight of this organ under basal conditions and that it inhibited the stimulating effect of exogenous testosterone on the prostate. The fraction with a molecular weight above 10,000 daltons contains 76% Lowry proteins from the total pineal extract and 4% aminic nitrogen and in the polyacrylamide gel electrophoresis it appears as two protein bands. The fraction with a molecular weight under 10,000 daltons contains only 20% proteins and 26% aminic nitrogen from the total pineal extract. Paper chromatography of the amino acids has shown that the lower molecular weight fraction does not contain proline, tyrosine, arginine, lysine and histidine and that in both fractions prevail the aspartic and glutamic acids.

Inhibition of testosterone-induced prostate growth in the rat by melatonin-free pineal extract

Administration of the melatonin-free pineal extract to rats concomitantly receiving testosterone propionate caused partial inhibition of the ventral prostate growth induced by testosterone. Administration of the pineal extract to rats likewise caused a statistically significant decrease in the ventral prostate weight under basal conditions. The mechanism of action is discussed.

Studies on the purification of the antigonadotropic melatonin-free pineal extract

Partial purification of a melatonin-free extract obtained from bovine pineal and showing an antigonadotropic activity was studied. The following methods were utilized: Sephadex gel filtration, ultrafiltration, precipitation by alcohol, ammonium sulphate and trichloracetic acid. The fractions obtained by all these procedures as well as the dialysed extract were biologically tested through the mouse uterine test. The protein contents in all the substances studied were assayed by Lowry's method. The results showed that in the extract studied, the antigonadotropic activity was present both in the fraction under 10,000 and in the fraction above 10,000, the latter containing 72% of the proteins from the total extract.

Decrease of testosterone, cholesterol and ascorbic acid in the rat testis after administration of pineal polypeptides

Administration of 2 ml/day/animal, of melatonin-free pineal extract to the rat for three days induced a significant decrease in the testicular tissue concentration of testosterone, cholesterol and ascorbic acid. A dose of 1 microgram melatonin/day/animal given for 3 days did not alter these biochemical elements implied in testicular steroidogenesis.

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.

The role of the pineal gland in the lipid metabolism

The study contains the data gathered with time with regard to the involvment of the pineal gland in the lipid metabolism. Thus, it has been demonstrated that administration of the pineal extract lowers serum, hepatic, adrenal and testicular cholesterol of rat and that pinealectomy causes reverse effects. Administration of melatonin did not cause significant alterations. The same pineal extract reduced cholesterolemia, biliary cholesterol and serum phospholipids in rabbits whereas the absence of the pineal gland caused an increase in cholesterolemia, total lipids and FFA. Pineal treatment reduced the major lipid components of the blood and aorta in experimental atheromatosis induced in rabbits. The results presented in this paper demonstrate the inhibiting role played by the pineal gland in the lipid metabolism.

Anti LH and FSH activity of the human urinary antisteroid substance

The antisteroid urinary substance was checked out for its effect on LH and FSH under endogenous (castrated animal) and exogenous (administration of releasing hormone-GnRH) stimulation of the rat hypophysis. Administration of this substance partly blocked the castration induced LH and FSH serum increase by 65% and 37% respectively (p less than 0.01) and inhibited the GnRH stimulating effect depressing serum LH by 50% and FSH by 33% (p less than 0.05). In both experiments the LH and FSH content of the hypophysis was not influenced.

Anti-LH and FSH activity of melatonin-free pineal extract

The influence of melatonin (MEL)-free pineal extract on luteinizing hormone (LH) and follicle stimulating hormone (FSH) was studied comparatively with that of MEL. Administration of pineal extract to rats, 3 days running, was found to induce a statistically significant decrease of serum LH and FSH. This effect was also demonstrated by the biological tests used, namely, a decrease in weight of both rat ventral prostate (anti-LH activity) and mouse uterus (anti-FSH activity). MEL administered for 3 days, in doses of 1 microgram/day in the ventral prostate weight test or of 10 microgram in the uterine weight test, failed to induce comparable effects. The identity of the pineal substances responsible for the anti-gonadotropic activity of the pineal gland is discussed.

Pineal compounds with antigonadotropic activity

The work presents the experimental data reported by specialty literature as well as those reported by the authoress on studying the pineal substances with antigonadotropic activity, namely the indole compounds and pineal polypeptides. The effects observed after administration of melatonin--prototype of the pineal-indole family--and of more or less purified pineal extracts are presented. The matter discussed upon is whether or not melatonin or arginine-vasotocin are the pineal hormones responsible for the complex actions induced by the pineal extracts.

Circadian variations of ascorbic acid and cholesterol in the testis of intact and pinealectomized rats

The circadian variations of the testicular ascorbic acid and testicular cholesterol in the intact and pinealectomized rat were followed up. The results show that in both lots there are diurnal variations of these biochemical indices. Pinealectomy does not alter the values curve as concerns the testicular ascorbic acid but causes a reversal in the testicular cholesterol curve especially during the darkness period (the intact rat has an increased value of 2400 hrs whereas the pinealectomized one has the lowest value for the same hour).