Testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) in plasma of rabbit from birth to adulthood. Correlation with sexual and behavioural development

Abstract

Abstract. Plasma testosterone, LH and FSH levels were determined and correlated with reproductive organs growth, testicular differentiation, fighting and mounting behaviour in maturing rabbit. An infantile phase of development extends from birth to 40 days, characterized by low testosterone and FSH levels, decreasing LH levels (until 20 days) and by a slow growth of testis and seminal vesicle. The peripubertal phase starts abruptly around day 40. It is marked by simultaneous events: the appearance of mature Leydig cells in the testis, a striking increase in testosterone and FSH levels, a small rise in LH levels and an acceleration of testicular growth. The phase of rapid growth of seminal vesicle and the first meiotic divisions start around day 70, in presence of high circulating levels of FSH and testosterone. Fighting (3 months) and mounting behaviour (146 ± 13 days) occur lately after a long period of high circulating testosterone levels.

Patterns of plasma LH, FSH, oestradiol and corticosteroids from birth to the first oestrous cycle in Meishan gilts

“…The present study shows that these high concentrations result from high baseline values rather than from high frequency of pulses. A similar period of high LH secretion around birth has been observed in calves (Challis et al, 1974), guinea-pigs (Donovan et al, 1975), humans (Kaplan and Grumbach, 1976) and rabbits (Berger et al, 1982 (Diekman et al, 1983) or at about 240 days (Camous el al, 1985). In agreement with our previous results in Large White gilts (Camous el al, 1985), (Boyar et al, 1974;Parker et al, 1975), in rats (Meijs-Roelofs et al, 1983;Urbanski and Ojeda, 1985) and in sheep (Foster et al, 1975;Foster and Ryan, 1981 (Rayford et al, 1974;Diekman et al, 1983;Camous et al, 1985) and in other species, such as sheep (Foster et al, 1975), rats (Dehler and Wuttke, 1975) and cattle (Schams et al, 1981).…”

Pituitary Luteinizing Hormone and Follicle-Stimulating Hormone from Birth to Adulthood in Male Rabbit

“…As previously shown in a longitudinal study [Berger et al, 1981b], circulating LH levels were similar in immature and adult males while FSH levels increased with age. Expressing the data in terms of mean maximal increment in absolute units (T30-T0), allowed conclusions to be drawn about the capacity of the pituitary to respond, regardless of the basal hor mone level.…”

“…During this peripubertal stage, high levels of circulating testosterone, FSH and LH were also reported previously [Berger et al, 1981b). In rats, pituitary LH and FSH levels reached peak values during puberty and declined until adult age [Debeljuk et al, 1972;Dussauli et al, 1977;Dohler et al, 1977); while in rabbits, the highest values obtained in prepubertal males were maintained in adults.…”

“…The hypothalamic pitu itary unit plays a determinant role in the onset of puberty in the rabbit by increasing gonadotropin secretion [Berger et al" 1981b, c]. In this process, the pituitary responsiveness to LHRH may be involved.…”

Disruption of sexual function, FSH secretion, and spermiogenesis in rabbits following developmental exposure to vinclozolin, a fungicide

“…Secretions of both cell types are involved in differentiation of the reproductive system (Bloch et al 1971, Klonisch et al 2004. In rabbits, testosterone concentration in fetal blood/tissue remains high until birth, when it drops and remains low until PND 40 (Veyssiere et al 1976, Berger et al 1982.…”