Onset of puberty

Acne vulgaris typically begins around puberty and early adolescence it tends to present earlier in females, usually at about 12 or 13 years, than in males, 14 or 15 years, due to later onset of puberty in males. Acne has been estimated to affect 95-100% of 16- to 17-year-old boys and 83-85% of 16- to 17-year-old girls. Acne settles in the vast majority by 23-25 years of age, persisting for longer in some 7% of individuals 1% of males and 5% of females exhibit acne lesions at 40 years of age. There is a small group of individuals who develop late-onset acne, beyond the age of 25 years. 

Orbach J. and Kling A. (1966). Effect of sensory deprivation on onset of puberty, mating, fertility and gonadal weights in rats. Brain Res 73, 141-149. 

Evidence that BPH could be hormone related came from studies of a population of pseudohermaphrodites in the Dominican Republic. These individuals are genetically male, but do not display normal male genitalia until the onset of puberty. They are therefore raised as females until puberty. Studies revealed that these pseudohermaphrodites are deficient in an isoform of the enzyme steroid 5a-reductase, which is responsible for catalyzing the conversion of testosterone to dihydrotestosterone (DHT). In addition to the overt sexual manifestations of this condition, affected individuals show no incident of male pattern baldness, mild or no acne, and underdevelopment of the prostate. These observations led researchers to postulate that a selective inhibitor of steroid 5a-reductase would be an effective treatment for BPH. 

Reduced food intake and efficiency of food use, altered iron metabolism, clinical signs of copper deficiency. Onset of puberty delayed 10 weeks, decreased conception rate (fertility 12-33% vs. 57-80% in controls), disrupted estrus cycle (67% were anestrus vs. 7% in controls), and other signs consistent with decreased releases of luteinizing hormones associated with altered ovarian secretion (3, 4) Growth and fertilization normal liver copper 10 mg/kg DW only 16% of embryos developed normally (2)... 

Mice are able actively to seek or avoid priming pheromones that modulate their ovarian cycle and onset of puberty. Peripubertal female mice avoid the urine odor of adult males, known to accelerate puberty in females, and are more attracted to the odor of grouped adult females. This behavior is particularly effective because the active space of the (almost) non-volatile male pheromone is small, and prolonged exposure is required for the effect to occur (Coppola and O Connell, 1988). Likewise, prepubertal female mice do not urinate near urine marks of adult males, while grouped, estrous, and diestrous adult females do. Such behavior may help young females to avoid exposure to male odors until they reach puberty. This way they would be protected from mating too early, and their eventual reproductive success would be enhanced (Drickamer, 1989a). 

Rissman, E. F. and Johnston, R. E. (1986). Nutritional and social cues influence the onset of puberty in California voles. Physiology and Behavior 36,1-5. 

Other environmental factors have been examined in the NIMH cohort, with similarly negative results. Patients with COS do not have an exaggerated rate of psychosocial stressors (M. Lenane, unpublished data), and the timing of the onset of puberty in COS patients did not differ from that of their siblings or national norms (Frazier et ah, 1997). 

Mitsushima D, Hei DL, Terasawa E GABA is an inhibitory neurotransmitter restricting the release of luteinizing hormone-releasing hormone before the onset of puberty. Proc Natl Acad Sci USA 91 395-399, 1994 Miura N, Nakata N, Tanaka Y, et al Improving effects of FG-7080 a serotonin reuptake inhibitor on scopolamine-induced performance deficits of memory tasks in rats. Jpn J Pharmacol 62 203-206, 1993 Mizuta T, Segawa T Chronic effects of imipramine and lithium on 5-HT receptor subtypes in rat frontal cortex, hippocampus and choroid plexus quantitative receptor autoradiographic analysis. Jpn J Pharmacol 50 315-326, 1989... 

At the time of menarche or puberty, there may be only 300 000 -400 000 oocytes in the ovaries. With the onset of puberty, a second layer begins to form from cuboidal granulosa cells these cells arise from a small number of growing follicles that have an enlarged ooplasm and a zona pellucida. 

Altered sexual function and fertility. Toxicity may be expressed as alterations to the female or male reproductive organs, the related endocrine system or pregnancy outcomes. The manifestations of such toxicity may include, but not be limited to, adverse effects on onset of puberty, gamete production and transport, reproductive cycle normality, sexual behaviour, fertility, gestation, parturition, lactation, pregnancy outcomes, premature reproductive senescence or modifications in other functions that are dependent on the integrity of the reproductive systems. 

But more flax is not necessarily better. When the rat chow contained five percent flax by weight, there was delayed onset of puberty, but when the amount of flax was doubled onset of... 

Androgen synthesis in the human male fetus begins at the age of about 70 days when the testes enlarge and go through an important period of activity that begins the conversion of the infant body to a male type. Other bursts of testosterone synthesis occur during infancy, but there is little further synthesis until the onset of puberty.268 272... 

Serotonin and melatonin are evidently involved in maintenance of the 24-h circadian rhythm of the body (see Section 13).792/792a Melatonin regulates the sexual cycle in photoperiodic animals and influences the onset of puberty.792-794 The serotonin content of the brain is influenced by the diet, being higher after a meal rich in carbohydrates. Serotonin may serve as a chemical message sent from one set of neurons to the rest of the brain, reporting on the nature of dietary intake.784 Melatonin, which can readily form free radicals, may function as part of the body s antioxidant system.795 796... 

Adolescents. Documentation of the safety and efficacy of antidepressants and mood stabilizers is better for adolescents than for children, although not at the standard for adults. That is unfortunate, because mood disorders often have their onset in adolescence, especially in girls. Not only do mood disorders frequently begin after puberty, but children with onset of a mood disorder prior to puberty often experience an exacerbation in adolescence. Synaptic restructuring dramatically increases after age 6 and throughout adolescence. Onset of puberty also occurs at this time of the life cycle. Such events may explain the dramatic rise in the incidence of the onset of mood disorders, as well as the exacerbation of preexisting mood disorders, during adolescence. 

Long-term use of beclomethasone dipropionate 400-600 micrograms/day was reported to delay the onset of puberty. However, subsequent catch-up growth was unaffected and subjects reached their normal predicted adult height (147). 

Delayed Puberty. In males, androgens may be administered on a limited basis to accelerate the normal onset of puberty.124,125 These drugs are typically used when puberty is anticipated to occur spontaneously but at a relatively late date—that is, when puberty is not delayed because of some pathologic condition. 

Flaxseed consumption did not affect the pregnancy of the rats (Collins et al., 2003 Tou et al., 1998). Flaxseed (20% and 40%) and flaxseed meal (13% and 26%) diets did not affect fertility, litter size, or survival of offspring (Collins et al., 2003). However, length of gestation, anogenital distance and index, onset of puberty, and estrous cycles were affected by flaxseed consumption. 

Patients with constitutional delay in onset of puberty can be distinguished from those with hypogonadotropic hypogonadism using repeated hCG stimulation. Serum testosterone and estradiol levels rise in the former but not in the latter group. 

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