K. Rager

Ontogeny of Circadian Rhythmicity for Melatonin, Serotonin, and N‐Acetylserotonin in Humans

The serum concentration of melatonin, serotonin, and N‐acetylserotonin were measured by RIA procedures in 28 infants aged 1 week to 9 months. Blood specimens were obtained at 1200 hr and 2400 hr. A day‐night difference in serum serotonin was present immediately after birth. A significant (P < 0.001) decrease in serum serotonin concentrations at 1200 hr and 2400 hr was observed from the first month of age to the third to ninth month of age. A significant (P < 0.05) difference in day‐night N‐acteylserotonin concentration is first seen at age 1–3 months. Serum melatonin concentrations, though detectable, did not show any day‐night difference at birth. Melatonin concentrations progressively increased up to the third month of age, and a significant (P < 0.01) day‐night difference appeared thereafter. The results indicate that in humans the circadian organizatijon for serotonin already exists at birth, and the circadian melatonin rhythm develops after birth.

Sex steroid hormones during multiphase pubertal developments

Abstract Somatic changes during adolescence were related in this study to the breast or genitalia maturational ratings described by Tanner [1]. Urinary androsterone excretion in boys as well as in girls paralleled more the development of skeletal age as a maturational parameter than the chronological age of the adolescent individuals. Sex differences became obvious in relating the androsterone excretion in boys or girls to the skeletal maturity. A similar relationship between girls and boys to the skeletal development was encountered measuring testosterone excretion values. Plasma estradiol and estrone concentrations in girls and plasma testosterone and dihydrotestosterone levels in boys exhibited close correlations to the pubertal developmental stages. Estradiol levels in boys were highly correlated to testosterone concentrations, indicating that perhaps a significant portion of the estrogen is derived from circulating androgens. 5α-androstane-3α, 17β-diol showed a rise during the maturational stages in boys. Changes in the relationship between dihydrotestosterone/testosterone and androstanediol/testosterone indicate that there is an increment of 5α-reductase activity at the beginning of puberty. Longitudinal studies revealed parallelism between testosterone excretion in the urine and the plasma testosterone concentrations, showing the most marked increments between ages 12 and 14 years. In the rat it was found that plasma testosterone levels rose dramatically after the 25th day of life, the surge in dihydrotestosterone occurred at the 26th day of life, but the peak is reached later. These changes were compared to LH and FSH levels. The rate of increment in plasma FSH concentrations is greatest between 16 and 20 days of age and followed by a spurt in the LH concentration after day 20 of age. The abrupt rise in plasma testosterone seen after day 26 is perhaps mediated by the sudden rise in the two gonadotropins. Changes due to castration and cryptorchidism are discussed.

Determination of serum sex hormone binding globulin (SHBG) in preadolescent and adolescent boys.

Abstract The saturation assay for sex hormone binding globulin (SHBG) originally described by Rosner[1] has been modified to optimize assay conditions and the method applied to clinical studies. A set of equations is given which fully describes the assay system and helps to calculate various parameters. The use of filtration instead of centrifugation allows one to measure directly SHBG bound DHT and reduces the error due to the calculation by subtraction of nearly equal numbers in the indirect procedure of Rosner [1]. The improvement due to modification is demonstrated in detail, and a procedure is described for the assay of SHBG in human male serum. Normal values are given for boys during multiphase pubertal developments.

STUDIES ON THE RELATIVE SENSITIVITY FOR ANDROGEN FEEDBACK INHIBITION IN RATS DURING SEXUAL MATURATION

This set of experiments was designed to see : (1) the relative sensitivity of a number of androgens on the feedback inhibition of gonadotropins, (2) if there is any alteration in the magnitude of feedback inhibition with sexual maturation. Testosterone, dihydrotestosterone, 3α-androstanediol and androstenedione were given in one injection s.c. as 250 μg/100 g body weight at the ages 16, 23, 26, 35, 56, 65 and 90 days. 24 hrs later LH and FSH were measured. The results suggest, that(1) The 2 adrenal androgens DHA and Δ 4 have no suppressive action on the gonadotropins, (2) All potent androgens as T,DHT,3α-Adiol suppressed LH secretion the order being 3α-Adiol, DHT, T at the period of 26–35 days where maximum suppression was observed, (3) T and DHT both inhibited FSH in all ages in male rats, whereas 3α-Adiol was ineffective, (4) The inhibition of the gonadotropins was found to be age dependent with the same dose administered, (5) The same dose of androgens suppressed LH maximally at days 26 and 35. In younger animals the suppression was not as marked but significantly lower than seen in the older age groups, (6) For FSH the situation is not as clear as that for LH, but still comparable. T and DHT had bigger inhibition in premature animals than in adults.

200 MODULATION OF BASAL AND GRF-STIMULATED GH SECRETION BY MELATONIN AND VICE VERSA IN MALE RATS

In humans,release of GH due to insulin induced hypoglycemia was noted to inhibit the basal level of the pineal hormone melatonin(MEL) (Gupta et al,1983)and viceversa(Smythe and Lazarus, 1974).In order to study the interaction between stimulated GH and and MEL in adult male rats,the following studies were carried out:1.Effect of GH stimulation with GRF(1μg/bw,iv) ,l-dopa(5μg iv) and insulin hypoglycemia(4IE iv) on circulating MEL. 2.Effect of MEL(50μg sc for 4 days) on basal GH levels and effect of GH(50μg sc for 4 days) on circulating MEL concentrations. 3.Effect of MEL(50μg sc at -60 and -30 min) on GH release due to GRF,l-dopa and insulin. A significant(p < 0.01) increment in GH level(188±7 ng/ml,x±SEM) due to GRF decreased MEL concentrations while peaking of the former was synchronized with the nadir of the latter.The other two GH stimulators,although less effective,also suppressed MEL levels significantly(p < 0.05).MEL pretreatment suppressed significantly GH levels from the control(1.7±1 vs 16.7± 8,p < 0.05).Similarly,GH treated animals showed significantly suppressed MEL levels in relation to the controls(3.1±2 vs 70.9±8 pg/ml,p < 0.001).When GRF,1-dopa or insulin was administered to stimulate GH in the MEL pretreated animals,the peak was entirely abolished.The fact that the GRF induced GH release suppressed MEL and pretreatment with MEL suppressed the GH response to GRF indicates a possible interaction at the pituitary level.

Quantitative and qualitative analysis of LH-RH test in normal and endocrinologically sick pre-adult subjects

The pattern of LH-RH evoked (50 μg/M2 i.v.) release of LH and FSH was analyzed quantitatively as well as qualitatively in 123 normal and in 286 endocrinologically sick pre-adult subjects to characterize the functional state of their gonadotostat. The common methods applied to assess this functional state are not adequate enough to differentiate the quantitative and qualitative patterns of response, and therefore a comparative examination was carried out for the peak increment,net increment, area under the time-response curve till the peak value and the cumulative response, ie, the total area under the time-response curve in each subject. As almost all the parameters were just-normally or log-normally distributed, statistical assessment was based on non-parametric Mann and Whitney test. The cumulative response and median comparison gave more meaningful data, based on the magnitude and shape of the release pattern, for an accurate differential diagnosis.

SEX STEROID HORMONES DURING MULTIPHASE PUBERTAL DEVELOPMENTS

Somatic changes during adolescence were related in this study to the breast or genitalia maturational ratings described by Tanner[1]. The mechanism of this induction is uncertain. LH receptor populations do not appear to change during FSH exposure. Urinary androsterone excretion in boys as well as in girls paralleled more the development of skeletal age as a maturational parameter than the chronological age of the adolescent individuals. Sex differences became obvious in relating the androsterone excretion in boys or girls to the skeletal maturity. A similar relationship between girls and boys to the skeletal development was encountered measuring testosterone excretion values. Plasma estradiol and estrone concentrations in girls and plasma testosterone and dihydrotestosterone levels in boys exhibited close correlations to the pubertal developmental stages. Estradiol levels in boys were highly correlated to testosterone concentrations, indicating that perhaps a significant portion of the estrogen is derived from circulating androgens. 5α-androstane-3α, 17β-diol showed a rise during the maturational stages in boys. Changes in the relationship between dihydrotestosterone/testosterone and androstanediol/testosterone indicate that there is an increment of 5α-reductase activity at the beginning of puberty. Longitudinal studies revealed parallelism between testosterone excretion in the urine and the plasma testosterone concentrations, showing the most marked increments between ages 12 and 14 years. In the rat it was found that plasma testosterone levels rose dramatically after the 25th day of life, the surge in dihydrotestosterone occurred at the 26th day of life, but the peak is reached later. These changes were compared to LH and FSH levels. The rate of increment in plasma FSH concentrations is greatest between 16 and 20 days of age and followed by a spurt in the LH concentration after day 20 of age. The abrupt rise in plasma testosterone seen after day 26 is perhaps mediated by the sudden rise in the two gonadotropins. Changes due to castration and cryptorchidism are discussed.

IN VITRO-MICRO-BIOTRANSFORMATION OF PREGNENOLONE AND PROGESTERONE IN TESTIS BIOPSY MATERIAL OF CRYPTORCHID, BOYS

Testis biopsy materialswere taken from 10 cryptorchid boys during maldescensus operation, whereas normal materials were obtained from deceased patients. 3H-Pregnenolone and l4C-progesterone were used as substrates. Biotransformation of both substrates to testosterone was found to be diminished markedly in the cryptorchid materials when related to the normals. The normal testis biotransformed pregnenolone in a more pronounced way to the 5α -reduced substances, such as dihydrotestosterone and androstanediol, than did the eryptorchid materials. Those differences were less evident using labelled progesterone as a substrate. Here, androsterone was a major metabolite and the yield for, the cryptorchid tissues was significantly greater than that for the normals.In conclusion the cryptorchid testis showed marked differences in the pattern of biotransformation of the labelled steroid precursors.

SEXUAL HORMONE BINDING GLOBULIN (SHBG) DURING MALE PUBERTAL DEVELOPMENT IN NORMAL AND PATHOLOGICAL CONDITIONS

Since Testo-sterone is specifically bound to SHBG, this globulin may determine the availability of physiologically active testosterone at different stages of pubertal development. Furthermore its concentration could be of importance under pathological conditions, particularly in such cases, in which an androgen disturbance exists. To investigate this subject, a method for the quantitative determination of SHBG in human plasma was developed. 200 μl of plasma, steroid free after absorption to charcoal were incubated in excess with 3H-DHT at 37°C for 30 min. A 1:10 diluted portion was then precipitated with saturated ammonium sulfate, and filtered through a millipore membrane to separate the globulin fraction from albumin, free and albumin bound DHT. Taking into account that SHBG has one specific binding site, the molar concentration of SHBG in the globulin fraction was calculated considering the specific activity of DHT and the molecular weight of SHBG (=100,000). The results were expressed in mg/l. SHBG was measured in a group of normal boys and the results were evaluated in relation to the genitalia developmental stages. The average value of 4.8 mg/l in G I boys decreased to 1.8 mg/l in GIV-GV boys. Boys with disturbances of male development were also studied. In cryptorchidism higher SHBG concentrations were found when the values were considered according to chronological age or to bone age.

AGE-DEPENDENT CHANGES IN THE SYNTHESIS AND RELEASE OF PITUITARY GONADOTROPINS IN THE MALE RAT FOLLOWING LH-RH AND CRYPTORCHIDISM

Even with more understanding regarding the ‘shift’ in the hypothalamic sensitivity threshold occurring with the onset of puberty the synthesis and release of the pituitary gonadotropins in the intact male rat still remains in the dark. We have studied the pituitary content and circulating levels of LH and FSH in the intact animal and under the modulatory effects of LH-RH and bilateral cryptorchidism during sexual maturation. Both gonadotropins registered increment in content with maturation until day 35 of life and then declined. The peripheral levels however were not parallel with maturation, and while LH level rose to a new postmaturation height, the FSH concentration showed characteristic decline with maturity. With LH-RH the maximal depletion in the pituitary reserve of LH occurred at day 35 within 10–30 min post-LH-RH, during which period the peripheral circulation registered maximal concentration. Most prominent depletion of the pituitary reserve of FSH was also noted in the 35-day-old animals 30 min post-LH-RH with a concomitant rise in the peripheral concentration. Bilateral cryptorchidism caused marked depletion of the pituitary reserve of LH during this critical 30–35 day of life and raised the peripheral concentration to a high level. FSH, however, registered a simultaneous higher pituitary content and circulating level at comparable ages. The data revealed that the age 30–35 day in the life of the male rat is associated with the most dynamic changes in this regulatory mechanism.