[Induction in the newborn and maintenance in adulthood of a "male-type" growth or "female-type" growth depends on the nature of gonadic secretion (author's transl)].
The influence on the growth of the presence of testosterone or estradiol at some stage of development was investigated from birth to adult age (90 days). 1. The presence of the androgenic molecule in the newborn organism, regardless of genetic sex (intact males, males orchidectomized at 9 days and neonatally injected orchidectomized males; neonatally injected intact and ovariectomized females), starts up a growth acceleration six weeks later. 2. The presence of the estrogenic molecule during this same period (neonatally injected intact and ovariectomized females; neonatally injected orchidectomized males) decreases the growth rate when animals come into puberty. 3. The development of the adult is immediately accelerated by androgen (excitatory effect) or reduced by estrogen (inhibitory effect). On the contrary, the effects of sex hormones present in the early postnatal period appear much later (inductive effect). Therefore, the activity patterns of sex hormones change with age: in the adult, androgen increases anabolism and estrogen decreases food intake; in the newborn, an undifferenciated mechanism responsible for growth is organized into "a male type" by androgen or "female type" by estrogen. The nature of this mechanism is discussed.
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology / Q000502:physiology*; D005260:Female; D006066:Gonads / Q000502:physiology; D006128:Growth; D008297:Male; D051381:Rats; D012737:Sex Factors; D013739:Testosterone / Q000494:pharmacology / Q000502:physiology*
D013739:Testosterone; D004958:Estradiol
Induction chez le nouveau-né et entretien chez l'adulte d'un type de croissance mâle ou femelle, selon la nature des hormones sécrétées par les gonades chez le rat