Pubertal Testosterone Research Articles

The role of postnatal testosterone in the development of sexually dimorphic behaviors in DBA/1Bg mice

The DBA/1 Y chromosome causes an increment in aggression and pubertal testosterone levels. The purpose of the following experiments was to determine whether pubertal testosterone is necessary for the normal development of both aggression and copulation in males. If it is, then the effect of the DBA/1 Y chromosome may be mediated by its influence on pubertal testosterone. Individuals were either castrated at 30 days of age (CAS30) or sham operated (Sham or CAS50). At 50 days of age, the CAS30 individuals were sham operated and replaced with testosterone, while the CAS50 group was castrated and replaced with the same quantity of testosterone. The shams were sham operated at 50 days of age. CAS30 individuals were less aggressive than the CAS50 group, while they were no less aggressive than the sham operated group. Additionally, no groups differed in male copulatory behaviors. The results are discussed in relation to Y chromosomal and developmental mechanisms of sexually dimorphic behaviors.

Organisational effects of neonatal and pubertal testosterone on sexually differentiated behaviours in the open-field and head-dip apparatus.

On days 1 and 4 after birth rats were injected with 100 μg of testosterone propionate (TP) or vehicle, and at 35 days of age they were injected intramuscularly with 400 μg of testosterone oenanthate (TO), a long acting androgen, or the vehicle. There were four groups (oil-oil, TP-oil, oil-TO, TP-TO), each group subdivided by sex. Females treated with testosterone neonatally or at puberty were masculinised or defeminised on adult open-field behaviours, being less active and rearing less than oil-oil females; the oil-TO group also defaecated significantly more than controls. The TP-TO female group was indistinguishable from the oil-TO group. In a second experiment, sex differences were found in head-dipping behaviour as well as in activity and rearing. Females treated with TP or TO reared less and defaecated more than controls, and TP also decreased activity, but neither hormone treatment affected head-dipping behaviour. There is thus a peripubertal as well as a neonatal period when testosterone can act organisationally to masculinise or defeminise female rats. Potentiation between effects of neonatal and pubertal androgens was found on female body weights. TO alone had no effect, but TP-TO females were significantly heavier than controls at 90 days of age and by 130 days of age the TP-oil group was also heavier than controls.

EFFECTS OF NEONATAL ADRENALECTOMY AND CASTRATION ON HORMONAL CHANGES IN PUBERTAL BULLS

Plasma samples from intact, adrenalectomized, adrenalectomized and castrated and castrated bulls were assayed for LH, testosterone, androstenedione and oestradiol-17 beta from birth to 26 weeks of age. The adrenalectomized bulls, unlike the intact bulls, failed to show a rise in androstenedione at 14.5 weeks of age or a rise in testosterone at 20 weeks of age. Testosterone levels in the castrated animals remained below 0.4 ng/ml whereas androstenedione reached levels similar to those in intact bulls by 26 weeks of age. In all animals the concentration of oestradiol-17 beta in plasma remained below 25 pg/ml, although intact bulls had the highest levels. Levels of LH rose after castration but not after adrenalectomy. These data show that in bull calves absence of the adrenal glands during prepuberty delays the rise in pubertal testosterone by at least 10 weeks.