Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Observing many researchers using the same data and hypothesis reveals a hidden universe of uncertainty

This study explores how researchers' analytical choices affect the reliability of scientific findings. Most discussions of reliability problems in science focus on systematic biases. We broaden the lens to emphasize the idiosyncrasy of conscious and unconscious decisions that researchers make during data analysis. We coordinated 161 researchers in 73 research teams and observed their research decisions as they used the same data to independently test the same prominent social science hypothesis: that greater immigration reduces support for social policies among the public. In this typical case of social science research, research teams reported both widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers' expertise, prior beliefs, and expectations barely predict the wide variation in research outcomes. More than 95% of the total variance in numerical results remains unexplained even after qualitative coding of all identifiable decisions in each team's workflow. This reveals a universe of uncertainty that remains hidden when considering a single study in isolation. The idiosyncratic nature of how researchers' results and conclusions varied is a previously underappreciated explanation for why many scientific hypotheses remain contested. These results call for greater epistemic humility and clarity in reporting scientific findings.

[Enzymatic aspects of severely acute diarrheal disease in infants]

Acute dehydration of diarrhoea of the breast-fed child is a type of hypovolemic shock which, by its severity and frequency is one of the major emergencies of pediatrics. The liver, as the site of many metabolic processes is mainly affected in the frame of the multiple-tissue involvement which is characteristic for this condition. The authors carried out a study of several enzymes (total LDH and the thermally-labile fraction, gluthamatdehydrogenase, gammaglutamyltranspeptidase, acid and alkaline phosphatase) in 27 breast-fed children. Determination of the enzymes was done on hospitalization, and 10 days later. The study showed that all the enzymes that were evaluated had moderate increases in 40.7-71% of all cases. The increases were significant (p less than 0.001). After 10 days the enzyme titers showed a tendency to become normal again, and slightly higher values were found in only 15-12% of all cases. Minimal hepatopathy can be considered, associated to the clinico-biological evolution of this severe conditions of the breast-fed child pathology.

The antisteroid, antigonadotropic and metabolism-regulation activity of the pineal gland

This is a synthetic presentation of the data accumulated along almost fourty years in the Institute of Endocrinology in Bucharest, on the biology of the pineal gland. Most of these were included in the book treating on the pineal gland as an organ of metabolic regulation. The works revealed hypoglycemic, anabolic, anticholesterolemic and glomerulotrophic action of the pineal peptides as opposed to the pinealectomy which induced completely opposite effects. It was also demonstrated that the pineal gland has an antisteroid action, being both anticorticosteroid and antiandrogenic; the antigonadotropic action was also revealed on the basis of the classical method in endocrinology in which two states of plus or of minus of the glandular secretions show diametrically opposed phenomena. Researches on the hormonology of the pineal gland led to the production of a biologically active peptide extract which was finally turned into a medicine under the name of Crinofizin. The therapeutic indications of this drug are also presented.

Effect of pineal treatment on rat HDL-cholesterol under basal conditions and under stimulation with HCG

The effect of the pineal extract and that of two fractions, f1 and f2, one above, the other 10,000 daltons obtained by ultrafiltration of the extract, on HDL-cholesterol as well as on cholesterolemia and testosterone, under basal conditions and under exogenous HCG stimulation was followed up. Under basal conditions, the pineal extract induced a statistically significant decrease in the 3 biochemical indices, an effect which was also recorded with the two fractions, with the difference that the effect of f2 is more intense and significant as compared to f1, whereas the effect of the pineal extract appears more intense than that of the fractions. Under exogenous HCG stimulation, the pineal extract and less the fractions, partly inhibited the lowering effect of HCG on cholesterol and the rising effect of this hormone on testosterone. The role of the equilibrating agent of the pineal extract on HDL-cholesterol, cholesterolemia and testosterone, is discussed.

Decrease in high-density lipoprotein cholesterol after administration of melatonin-free pineal extract in the rat

The work was focused on the effect of the pineal extract on HDL-cholesterol alongside the effect of the same extract on serum cholesterol and testosterone in the rat under basal conditions. HDL-cholesterol is utilized in the rat, preferentially by the Leydig cells for steroidogenesis. Administration of melatonin-free pineal extract, in doses of 2 ml/day/animal along 3, 6 and 12 days caused a statistically significant decrease in HDL-cholesterol of 19, 21 and 20%, respectively. The same depressor effect occurred 4 hr following a unique injection of pineal extract (-25%, p less than 0.001). Cholesterolemia decreased significantly alongside with HDL-cholesterol (14, 18, and 16% after 3, 6 and 12 days and 18% after 4 hr). The effect of the pineal extract on testosterone tested in only two experiments was to depress it significantly by 43% after 4 hr and 45% after 6 days of treatment. The decrease in testosterone level following the decrease of its major precursor, cholesterol, is discussed.

The antigonadotropic activity and amino acid composition of a total and dialyzed melatonin-free pineal extract

The antigonadotropic activity of a melatonin-free pineal extract before and after a 24 h dialysis was assessed by the mouse uterine-weight test. In both cases, the uterus-stimulating effect of HCG was inhibited, showing that after dialysis the extract not only retains its effect but that the latter is even higher. The amino acids content established by an amino acid analyzer was the same in two batches of extract obtained from two different stores of pineal powder. The analyzer also showed that the glutamic acid is the prevailing component as a free and bound amino acid in the total extract. It was also found that methionine is absent from the dialyzed extract. Qualitative analysis of the pineal extract revealed 16 amino acids and a concentration of proteins of 1.90-1.96 mg/ml. Quantitatively, the glutamic and aspartic acids, proline and glycine prevail over the other constituents. The glutamic acid concentration was over two times higher than the latter three.

Effect of melatonin-free pineal extract on acid phosphatase activity in the testosterone-treated, castrated rat

The effect of a melatonin-free pineal extract on acid phosphatase activity in the prostate of castrated and testosterone-treated rat was studied. Prostatic acid phosphatases in the mature rat are lysosomal and secretory, the former being inhibited by tartrate. Castration induces a decrease in the secretory phosphatases and an increase in the lysosomal ones with a subsequent increase in the tartrate-induced inhibition index. The specific activity of total acid phosphatase also rises. Administration of the pineal extract in the first 4 post-surgical days did not have a significant effect, but when it was prolonged to 7 days, it partially inhibited the effect of castration on prostatic acid phosphatase. Administration of testosterone to the castrated rat in the first 4 post-castration days, partially compensated the prostatic alterations, owing to the fact that the prostate is under the control of androgenic hormones. Administration of both pineal extract and testosterone in the first 4 post-castration days partially inhibited the effect of testosterone. The equillibrating role of the melatonin-free pineal extract and its effect in relation to the amount of time lapsed from surgery is discussed.

Effect of melatonin-free pineal extract on sialic acid in hemicastrated and testosterone-treated rats

Administration of a melatonin-free pineal extract to hemicastrated rats in doses of 2 ml/day/animal induced a statistically significant decrease in their serum and testicular sialic acid after 3 days but not after 30 days of treatment. Unilaterally castrated rats receiving testosterone (6 injections) showed 10 days post-castration a statistically significant decrease in sialic acid in their serum and testes but not in the epididymis. Twenty-one days post-castration, time in which 11 testosterone injections were given, the sialic acid was low in the epididymis as well. Concomitant administration of testosterone and pineal extract caused a total reduction in the serum and partial reduction in the testes, of the lowering effect of testosterone on sialic acid. The return to the normal values of the serum sialic acid, to almost normal values of the testicular sialic acid and the increase over the normal values of the epididymal sialic acid shows the equilibrating role played by the pineal extract on the sialic acid in the hemicastrated rat treated with testosterone. The role of the melatonin-free pineal extract on sialic acid, a biochemical index involved in reproduction, is discussed.

Comparative study of the effects of melatonin-free pineal extract and melatonin on biochemical and hormonal parameters in the rats

A melatonin-free pineal extract administered to rats in doses of 2 ml/day/animal along 12 days, induced a statistically significant drop in urinary 17 KS, cholesterolemia, hepatic, adrenal and testicular cholesterol. The dose of 1 microgram melatonin/day/animal did not alter these biochemical indices. This dose administered for 3 days did not affect the serum level and testicular concentration of testosterone, unlike the pineal extract which lowered significantly serum and testicular testosterone. Unlike the pineal extract administration of melatonin in doses of 10 micrograms/day/animal along 3 days had no effect on DNA, RNA and testicular proteins. Administration of the pineal extract lowered significantly serum LH and FSH after 3 days whereas melatonin in doses of 50 micrograms/day/animal did not have a similar effect. Furthermore, while the pineal extract inhibited the post-castration elevation of LH and FSH, melatonin in doses of 50 micrograms/day/animal had no effect. The same difference was noted with rats under GnRH stimulation: the pineal extract inhibited the pituitary response to GnRH whereas melatonin did not. The authors conclude that the effects produced by the pineal extract are not mediated by melatonin.

Melatonin-free pineal substance, an equilibrating hormone?

This paper presents data revealing the regulating, equilibrating role of the melatonin-free pineal extract. Administration of this extract lowered statistically significant urinary 17-Ks and cholesterolemia in rabbits and cholesterolemia, hepatic cholesterol and ascorbic acid in the rat under basal conditions. When the initial values of these biochemical indices in the above mentioned animals were below the basal values established, then the pineal extract showed an effect of correction of these values increasing them toward the basal level. Under HCG stimulation total free and esterified cholesterol in the serum and testis as well as the DNA, RNA and proteins in the testicular tissue showed lower values than in the controls. Administration of the extract at the same time with HCG, corrected the HCG-induced lowering effect on these biochemical indices. Similarly, when GnRH induced a decrease and not an increase in serum LH, as expected, the pineal extract played the same regulating role causing rise of serum LH towards the initial values. In one of our experiments in which TRH induced a decrease and not an increase in serum prolactin, the pineal extract corrected this effect. These data suggest an equilibrating role played by the melatonin-free pineal extract in our researches on the pineal gland.

Effect of pineal treatment on testicular biochemical parameters under basal conditions and after stimulation with HCG in the rat

The effect of a melatonin-free pineal extract on sialic and ascorbic acid, nucleic acids (DNA RNA), proteins, total, free and esterified cholesterol in the rat testis under basal conditions and after stimulation with HCG was followed up. The pineal extract induced a decrease in sialic and ascorbic acid, total and esterified cholesterol, but it increased the proteins and RNA after 3 days of treatment, under basal conditions. The decrease in RNA and proteins was noticed after 30 days of treatment. Administration of HCG increased the sialic and ascorbic acids and decreased the total and esterified cholesterol, proteins and DNA without affecting RNA and free cholesterol in the testicular tissue. Concomitant administration of HCG and pineal extract showed that the pineal treatment corrected partially and sometimes completely the increasing or decreasing effect produced by HCG on the biochemical indices studied. The decrease in testicular esterified cholesterol the latter associated with androgen hormone synthesis, brings into discussion the role of the pineal gland in testicular testosteronogenesis, as the same pineal extract also caused a decrease in testosterone. The authors also discuss the regulating role of the pineal gland on some testicular biochemical indices.

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.

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)

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.

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.

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.

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.

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.

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).