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PubMed1998

[Allozyme heterozygosity, sexual maturation rate, and longevity].

Humans, animals, and plants are shown to have a universal polygenic system maintained by stabilizing selection, which underlies highly significant correlations between multilocus allozyme heterozygosity, the sexual maturation rate, and longevity. For 77 animal and 30 plant species, it was demonstrated that allozyme genomic heterozygosity (1) is positively correlated with rate of sexual maturity (2) (r12 = 0.815, P < 0.001) and negatively correlated with longevity; (3) (r13 = -0.793, P < 0.001). These relationships are significantly affected by the genotype-environment interactions that modify the structure of the metabolism related to growth and development. An increase in the number of heterotic genes involved in growth and development increases the energy expenditure in this ontogenetic period, accelerates the sexual maturation rate, and shortens the life span.

Animals↗
PubMed1984

Body weight and composition of Japanese quail (Coturnix coturnix japonica) at sexual maturity.

The influence of dietary protein (26%, 24%, 20%, 16%, and 14%) and restricted feeding (100%, 80%, and 60% of ad libitum) on body weight and body composition of Japanese quail (Coturnix coturnix japonica) at sexual maturity was examined in two similar experiments. Although less variable than chronological age, body weight at sexual maturity also differed significantly. In Experiment 1, there were no significant differences in breast weight, tibia length or carcass fat due to diet. In Experiment 2, differences in body composition were apparent as age at the onset of lay was increased by dietary manipulation. Early maturing quail tended to enter lay when a minimum chronological age or critical body lipid level was reached; late maturing quail entered lay when a critical lean body weight or skeletal size was reached. It is proposed that multiple threshold traits associated with growth and body composition are critical for the onset of sexual maturity.

Aging↗
PubMed1989

The development of puberty and sexual maturity in the Australian Swamp buffalo bull.

Testes from 47 juvenile Swamp buffalo bulls were examined for puberty and sexual maturity histologically and daily sperm production per gram of testis parenchyma was determined by enumeration of elongated spermatids in homogenates of testis parenchyma. Puberty was defined as the attainment of a daily sperm production per gram of testis parenchyma>0.5x10(6). In most bulls, puberty is attained by 24 mo of age, when scrotal circumference (SC) is approximately 16 cm, and liveweight exceeds 135 kg. Sexual maturity was defined as the attainment of adult levels of daily sperm production per gram of testis parenchyma (14x10(6)). In most bulls, this occurs at 30 to 33 mo of age, when SC is in the 17-to 20-cm range, and liveweight generally exceeds 250 kg. There was marked individual variation in age, liveweight and SC at both puberty and sexual maturity.

Journal Article↗
PubMed1991

Sexual maturation and blood pressure levels of a biracial sample of girls.

A cross-sectional survey of 142 black and 361 white girls was performed to investigate whether differences in the timing of maturation account for blood pressure differences between same-aged subjects. Data were collected on blood pressure, anthropometric parameters, socioeconomic status, and secondary sex characteristics. Analysis of covariance was used to determine whether blood pressure for black and white girls differed significantly after adjusting for the confounding effects of different body size and sexual maturation distributions of the two groups. Advanced sexual maturation of the black girls contributed as much as the larger body sizes of the black girls to the blood pressure differences found between the black and white girls. Assessment of an individual's stage of sexual maturation at blood pressure measurement should be considered as important as the measurement of height and weight.

Adolescent↗
PubMedDate not supplied

Involvement of brain serotonin in regulation of sexual maturity in male rats.

We have studied the effect of a reduction in the serotonin level at different times in the prepubertal period on the neuroendocrine and morphometric characteristics of sexual maturation of male rats. We established that injection of p-chlorophenylalanine, a blocker of serotonin synthesis, into male rats on the 30th and 34th day of life leads to activation of the endocrine function of the testes in 60-day-old animals. Injection of the preparation at later times, 40th and 44th day, produced a marked inhibiting effect on sexual maturation, expressed as inhibition of both the spermatogenic and the endocrine function of the testes of the animals investigated. The data obtained allow an assessment of the dual role of serotonin in the regulation of the rate of sexual maturation of male rats at different prepubertal periods.

Animals↗
PubMed1988

Growth and sexual maturation in paediatric patients treated by dialysis and following kidney transplantation.

Linear growth and sexual maturation were assessed in 48 children during dialysis treatment and in 68 children following renal transplantation. Height at the onset of haemodialysis treatment was more than 2 SD below the mean in 33% of prepubertal children. During dialysis treatment most children showed a progressive deterioration in SD score. The onset of puberty and sexual maturation was delayed but was in accordance with bone age. After transplantation 59% of prepubertal children had a normal height increment. Onset of puberty was recorded at a chronological age of 14.6 +/- 1.9 years in boys and 13.3 +/- 1.9 years in girls. The peak of the pubertal growth spurt was 6.6 +/- 1.6 cm/year in boys and 6.5 +/- 2.9 cm/year in girls. The duration of pubertal development in transplanted children was within normal limits. In transplanted girls menarche was achieved at a mean chronological age of 15.9 years and bone age of 12.9 years. Adult height was achieved at a mean age of 20.3 years in men and 18.7 years in women. Overall, one third of the children attained an adult height more than 2 SD below the mean. These data indicate that poor growth is achieved in most children on dialysis treatment; following transplantation normal growth may be restored. However, poor growth before kidney transplantation and the loss of growth potential during pubertal development have a great influence on adult height.

Adolescent↗
PubMed1988

N-(2,4-dinitrophenyl)-5-methoxytryptamine, a novel melatonin antagonist: effects on sexual maturation of the male and female rat and on oestrous cycles of the female rat [corrected].

N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] has recently been synthesized and shown to antagonize the inhibitory effect of melatonin on the release of dopamine in vitro from the hypothalamus of female rats. In the present study the ability of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] to inhibit in vivo the following melatonin-mediated effects was investigated: (1) delayed sexual maturation of young male rats, (2) delayed sexual maturation of young female rats, (3) inhibition of ovulation in mature female rats and (4) re-establishment of oestrous cycles in adult female rats maintained in continuous light. The inhibitory effect of daily melatonin injections, given in the afternoon, on the growth of the prostate gland and seminal vesicles and on serum testosterone concentrations in young male rats was prevented by daily injections of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected]. Daily injections of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] alone did not affect sexual maturation of young rats. In young male rats treated through the drinking water with melatonin, the growth of the accessory sex organs, but not that of the testes, was delayed and serum concentrations of testosterone were lower than in untreated rats. Administration of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] through the drinking water increased serum concentrations of testosterone but did not significantly affect the weights of the accessory sex organs. Simultaneous administration of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] and melatonin through the drinking water prevented completely, in a dose-dependent manner, the melatonin-mediated decrease in epididymal weights and in serum concentrations of testosterone and partially inhibited the delayed growth of the prostate glands and seminal vesicles. In young female rats treated with melatonin through the drinking water for 30 days, the growth of the ovaries was inhibited and serum concentrations of oestradiol were lower than in untreated rats. The growth of the uterus was not significantly affected. Administration of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] through the drinking water did not significantly affect uterine and ovarian weights or oestradiol concentrations. Simultaneous administration of melatonin and N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] through the drinking water prevented completely the melatonin-mediated decrease in ovarian weights and in serum oestradiol concentrations. Ovulation during presumptive oestrus was prevented in adult female rats treated through the drinking water for 7 days with melatonin. Administration of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] alone did not significantly affect the average numbers of ova shed and corpora lutea present. Simultaneous administration of N-(2,4-dinitrophenyl)-5-methoxytryptamine [corrected] and melatonin prevented completely the melatonin-mediated inhibition of ovulation; the average number of ova shed was the same as in controls.(ABSTRACT TRUNCATED AT 400 WORDS)

5-Methoxytryptamine↗
PubMed1990

[Relationship between sexual maturation and subcutaneous fat].

Due to the great variability at the beginnings and the period of the puberty, authors have studied the modifications of the subcutaneous-fat and their relation with the sexual maturating. They have measured the skinfold thickness of biceps, triceps, subscapular and suprailiac in 358 boys from 10 to 15 years old and 424 girls from 8 to 14 years old inrelation to sexual maturating through the stages described by Tanner. It has been found more subcutaneous fat in girls than in boys (p less than 0.05). The boys increase their subcutaneous fat until the stage 3 (except the skinfold triceps) and decrease later (except the skinfold subscapular). In boys, the analysis of varianza, show that the variations are related with the sexual maturating and not with chronologic age.

Adipose Tissue↗
PubMed1987

Analysis of the physiological processes connected with sexual maturation of stallions.

Physiological processes connected with sexual maturation of stallions were observed on 10 half-breed Anglo-Arab stallions beginning from 8 months of age, until 4.5 years of age. It was found that there is full somatic and sexual development in the stallion reached around the age of 3.5 years, and the sperm morphology stabilized in the range of the physiological norm around 3.0 years of age. On the other hand biochemical components of the semen plasma such as glycerylphosphorylcholine (GPC), ergothioneine (EGT), total protein (PRT), up to age 4.5 years, reach significantly lower value than in mature stallions. This corresponds with lower freezability of stallion spermatozoa, up to this age.

Age Factors↗
PubMed1984

Testicular recrudescence in the golden hamster (Mesocricetus auratus): a possible model of sexual maturation.

The ability of cultured hamster Sertoli cells to respond to FSH was studied during sexual maturation and photoperiodically induced regression and recrudescence. Serum gonadotropins were also measured in donor animals to determine if changes in LH and FSH were associated with changes in Sertoli cell response (accumulation of intracellular cAMP). There was a maturational peak of gonadotropins and an age-related decline in the ability of Sertoli cells to respond to FSH; the decline began before the peak of either gonadotropin. During regression, LH and FSH levels fell to or below prepubertal values, and the Sertoli cell response to FSH returned after the testicular weight had fallen from 2000 to 1400 mg/testis. Maximal Sertoli cell response to FSH occurred at approximately 800 mg/testis. During recrudescence, the low serum gonadotropin levels rose, reached a peak, and declined again to adult levels. The peak of gonadotropins during recrudescence was larger than that observed during maturation, and the loss of Sertoli cell response to FSH during recrudescence was delayed until after the gonadotropin peak. These data suggest that testicular recrudescence in the hamster is a dynamic process that approximates sexual maturation, but may be regulated in a somewhat different manner.

Aging↗
PubMed2006

[A preliminary study on the effect of prepubertal exposure of male rats to diethylstilbestrol on the apoptosis of spermatogenic cells after sexual maturation and its mechanism].

OBJECTIVE: To preliminarily study the effect of prepubertal exposure of male SD (Sprague-Dawley) rats to diethylstilbestrol (DES) on the apoptosis of spermatogenic cells after sexual maturation and its mechanism. METHODS: Thirty 21-day-old male SD rats were randomly divided into 4 experimental groups, DES 0.01, 0.1, 1.0 and 10.0 microg/(kg x d) and 1 control group. The experimental groups were injected (s.c.) with different doses of DES (dissolved in corn oil) during prepuberty [from postnatal day (PND) 22 to PND 35] and the control group with medium only. The apoptosis and related proteins Bcl-2 and Bax expressions of testicular spermatogenic cells were studied with TUNEL and immunohistochemistry after the rats sexual maturation (at PND 64). RESULTS: Compared with the control group, the apoptosis of testicular spermatogenic cells in the DES 0.01 microg/kg group had no difference, but significantly increased in the DES 0.1, 1.0 and 10.0 microg/kg groups and the apoptosis increased with the increase of DES dose. In the control and DES 0.01 microg/kg groups, Bax protein expressed weakly but Bcl-2 protein strongly in spermatogenic cells. With the increase of DES exposure, Bax protein expression in spermatogenic cells increased but Bcl-2 protein expression decreased. CONCLUSION: Prepubertal exposure of SD rats to inappropriate dose of DES can make the apoptosis of spermatogenic cells increase after sexual maturation. Bax and Bcl-2 proteins participate in the apoptotic course caused by prepubertal DES exposure.

Animals↗
PubMed2005

Changes in tissue biochemical composition and energy reserves associated with sexual maturation in the ommastrephid squids Illex coindetii and Todaropsis eblanae.

The aim of this study was to investigate the biochemical changes that occur during sexual maturation of the squids Illex coindetii and Todaropsis eblanae. In both species, amino acids and protein content increased in the gonad throughout maturation, but the allocation of these nitrogen compounds from the digestive gland and muscle was not evident. A significant (P < 0.05) increase in the content of lipids and fatty acids was observed in the gonad and digestive gland. It seems that both species take energy for egg production directly from food, rather than from stored products. Analyses for cholesterol revealed a significant (P < 0.05) increase in the gonad, and the lipid content differences between species are potentially related to different feeding ecologies. The glycogen reserves in the gonad increased significantly (P < 0.05), suggesting that glycogen has an important role in the maturation process. It was evident that sexual maturation had a significant effect upon the gonad energy content, but because the energy variation in the digestive gland and muscle was nonsignificant (P > 0.05), there was no evidence that storage reserves are transferred from tissue to tissue.

Amino Acids↗
PubMed1999

Hormonal monitoring of age at sexual maturation in female Goeldi's monkeys (Callimico goeldii) in their family groups.

The aim of this study was to determine whether or not sexual maturation is attained in the family group in captive-born Goeldi's monkey (Callimico goeldii) and if so, at what age and body weight. To monitor ovarian activity in 14 female Goeldi's monkeys, urinary content of pregnanediol-3alpha-glucuronide (PdG) was determined using radioimmunoassay. Urinary samples were collected between the ages of 6 and 70 weeks. Subjects became sexually mature while still housed in their family groups, at a median age of 57 weeks (48-< 70 weeks). Median body weight at the age of sexual maturity was 473 g (N=10; 420-543 g). This corresponded to 90% of the median non-pregnant body weight of breeding females in our colony (526 g, N=8). Therefore, Goeldi's monkey is similar to Leontopithecus but different from Cebuella, Callithrix, and Saguinus, in terms of daughters ovulating in the family group and at a relatively young age.

Aging↗
PubMed1979

[Degree of sexual maturation as an index of biological age].

Attempt was made to establish some characteristics of sexual maturation, depending upon chronologic and biologic age. A total of 1277 girls from 8 to 17 years of age in the city of Sofia are included in the study. There were no cases of precocious of considerably delayed pubertal development. Essential differences were found in the body dimensions, in connection with the increase in the degree of sexual maturation in one and the same chronologic age. The importance of biologic age for the individual approach to teen-agers girls and boys is emphasized.

Adolescent↗
PubMed2002

Is obesity associated with early sexual maturation? A comparison of the association in American boys versus girls.

BACKGROUND: Increasing evidence suggests a close association between early sexual maturation (SM) and obesity in girls and female adults. Earlier maturing girls are more likely to be obese than nonearly maturers. However, limited research has been conducted in boys. OBJECTIVE: To examine the influence of early SM on fatness in boys and compare it with girls, and to test the hypothesis that the associations differ by gender because of the differences in growth and SM patterns in boys and girls. STUDY DESIGN: Cross-sectional study. SUBJECTS: One thousand five hundred one girls and 1520 boys (aged 8-14 years) who participated in the Third National Health and Nutrition Examination Survey survey (1988-1994) and had complete anthropometry (weight, height, skinfold thickness) and SM data. METHODS: Based on each individual's age and SM status (Tanner stages: genitalia stages for boys and breast stages for girls), the subjects were classified as: 1) early maturers (those who reached a certain Tanner stage earlier than the median age for that stage), and 2) the others (average and later maturers). Overweight was defined as a body mass index (BMI) > or =85th percentile, and obesity > or =95th percentile. Logistic regression analysis was to test how early maturation affected the risks for overweight and obese. Using multiple linear regression models, the associations between fatness (BMI and skinfold thickness) and SM were systematically examined. Covariates including age, ethnicity, residence, family income, energy intake, and physical activity were adjusted. RESULTS: Early SM was positively associated with overweight and obesity in girls, but the associations were reverse for boys. The prevalence of overweight in early maturers versus the others was 22.6% versus 31.6% in boys and 34.4% versus 23.2% in girls; the figures for obesity were 6.7% versus 14.8% and 15.6% versus 8.1%, respectively. Odd ratios and 95% confidence intervals for obesity were 0.4 (0.2, 0.8) for boys and 2.0 (1.1, 3.5) for girls, and covariates were adjusted. Most significant differences in overweight and obesity among ethnic groups disappeared after controlling for SM. Fatness (BMI and skinfold thickness) was associated with SM stages and with early maturation in boys and girls, but the associations were in opposite directions. Compared with their counterparts, early maturing boys were thinner, whereas early maturing girls were fatter. CONCLUSIONS: Obesity is associated with sexual maturation in both boys and girls, but the association differs. There is positive association in girls, but a negative one in boys. Maturation status should be taken into consideration when assessing child and adolescent obesity.

Adipose Tissue↗
PubMed1994

Differential regulation of vitamin D receptor and intestinal calcium transport occurring during sexual maturation in the fowl (Gallus domesticus).

Quantitative measurements of intestinal vitamin D receptor (VDR) and calcium transport taking place in individual villus-attached enterocytes have been compared during the onset of sexual maturity to test for a direct involvement of VDR in controlling calcium transport across the chick small intestine. Chickens of all ages showed VDR to be present in crypt and villus enterocytes, the amounts of VDR declining only slightly during enterocyte migration from the crypts to the tips of villi. Calcium transport corrected for initial adsorption was lowest in the crypt and highest in villus tip enterocytes. These results are consistent with VDR initiation and possible later maintenance of calcium transport across differentiating enterocytes. The total amount of VDR determined along the crypt-villus axis was significantly less in immature 11-week-old compared with 17-week-old sexually mature non-laying and 25-week-old laying chickens. Calcium transport was significantly greater in 25-week-old compared with 17- and 11-week-old birds. This unexpected up-regulation of VDR in 17-week-old birds was not affected by dietary restriction of calcium. Increased VDR expression in 17-week-old sexually mature birds is probably initiated by estrogen acting indirectly to increase 1,25 (OH)2D3 production in the kidney. Increased calcium transport in 25-week-old laying chickens could involve estrogen interacting with estrogen receptors as well as 1,25 (OH)2D3 interacting with vitamin D receptors to promote gene transcription in the intestine.

Animals↗
PubMed2003

Effects of sex steroids, sex, and sexual maturity on cortisol production: an in vitro comparison of chinook salmon and rainbow trout interrenals.

Sex steroids appear to be responsible for hyperactivation of the hypothalamus-pituitary-interrenal (HPI) axis that occurs in mature semelparous Pacific salmon as a prelude to post-spawning (programmed) death. This study was undertaken to examine the direct effects of sex steroids on interrenal activity of semelparous (chinook salmon) and iteroparous (rainbow trout) salmonids using an in vitro incubation system. In addition, phenotypic sex differences in cortisol production by interrenals of sexually mature (spawning) rainbow trout and chinook salmon were investigated. Interrenal tissue from juvenile and sexually mature chinook salmon and rainbow trout was incubated for 48 h in culture medium containing either no steroid (controls), 1 microM estradiol (E2) or 1 microM 11-ketotestosterone (11-KT). This tissue was then challenged for 3h with either pregnenolone, dibutyryladenosine 3('):5(')-cyclic monophosphate (dbcAMP) or forskolin, or synthetic human adrenocorticotropic hormone (ACTH(1-24)). Sex differences in in vitro interrenal cortisol production were assessed using separate tissue pools challenged with the same agents. Cortisol in media was measured by radioimmunoassay. E2 suppressed the ability of juvenile chinook salmon interrenals to utilize pregnenolone as substrate for cortisol synthesis. In mature female chinook salmon the suppressive effect of E2 was less pronounced, but was observed as a reduced response of interrenals to both pregnenolone and dbcAMP. E2 did not affect ACTH(1-24) stimulated cortisol production. Immature and mature rainbow trout interrenals were both relatively insensitive to E2. 11-KT did not affect cortisol production by juvenile chinook salmon and juvenile or mature rainbow trout, and had only minor effects in male and female spawning chinook salmon. In mature chinook salmon and rainbow trout, the interrenals of females were more responsive to ACTH stimulation and showed a greater utilization of pregnenolone as a substrate than interrenals of males. Mature female rainbow trout were also more responsive to dbcAMP stimulation than males. The results of this study suggest that the onset of sexual maturation and gonadal steroid production may contribute to sexually dimorphic cortisol responses in vitro.

Animals↗