Sex-dependent differences in the effect of early weaning on the chosen hormones secretion in sheep during the postnatal transition to puberty – Preliminary results

Abstract

The influence of early weaning on the cortisol, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and growth hormone (GH) secretion in lambs of both sexes and testosterone (T4) level in male lambs during the postnatal transition to puberty was investigated by radioimmunoassay. It was hypothesized that this influence is long-term and sexually dimorphic. Hence, the effect of weaning at 5 weeks of age in comparison with the weaning at 9 weeks of age on hormone concentrations in peripheral blood plasma of 5-, 9-, 12-, and 16-week-old lambs of both sexes was investigated. The cortisol concentrations were greater (P<0.05) in control and early weaned female lambs than in male lambs at investigated stages. Weaning at 5 weeks of age resulted in the lover (P<0.05) cortisol secretion in male lambs in contrast to the greater (P<0.05) cortisol secretion in female lambs at 16 weeks of age. Weaning at 5 weeks of age stimulated (P<0.001) the FSH secretion, but reduced (P<0.001) the LH, GH and T4 secretion in 16-week-old male lambs. In female lambs early weaning inhibited (P<0.05) the FSH secretion at 9 weeks of age, LH secretion after 9 weeks of age and GH secretion after 12 weeks of age. Thus, early weaning results in the sexually dimorphic stress reaction that is more potent and long-lasting in female in contrast to male lambs. This maternal deprivation stress contributes to the inhibition of LH and GH secretion in lambs of both sexes and T4 secretion in male lambs during the postnatal transition to puberty.

The impact of the mother on the hypothalamic-pituit aryadrenal, hypothalamic-pituit ary-gonadal and somatotropic axes activity of offspring during postnatal ontogeny

“…Furthermore, in lambs weaned at 12 weeks of age an increased release of CRF from the nerve terminals in the median eminence and accumulation of ACTH in the pituitary gland were observed . Cieślak et al (2015) showed a sex-dependent differences in cortisol secretion in lambs subjected to maternal deprivation. In female lambs maternal deprivation caused the stimulation of cortisol secretion in all examinated periods (9 th , 12 th , 16 th week of life).…”

“…Secretion of the FSH was increased in male lambs after maternal deprivation in all examinated periods, furthermore in female lambs subjected to maternal separation diminished FSH secretion was observed in 9 weeks of age and increased FSH concentration in 12 an 16 weeks of age was noted (Tab. 1) (Cieślak et al 2015). Table 1.…”

“…Table 1. The schematic presentation of the cortisol, GH, LH and FSH secretory pattern during the postnatal transition to puberty in lambs subjected to maternal deprivation (Cieślak et al 2015). ↑ Stimulation; ↓ Inhibition, = No effect on hormone secretion 9 weeks of life 12 weeks of life 16 weeks of life…”

Effect of weaning method on body weight, testicular growth, sexual behavior, age of puberty, and testosterone concentration of Beetal bucks

“…It has been suggested that bucks had better growth when allowed to suckle for a longer period than those weaned early or abruptly (Palma & Galina, 1995). Besides the impact of growth rate on the age of puberty (Colomer‐Rocher et al., 1987), early weaning results in stress which inhibits the secretions of growth hormone and luteinizing hormone in lambs of both sexes and that of testosterone in male lambs during the postnatal transition to puberty (Chmielewska et al., 2015). Briefly, bucks that attain puberty earlier possess better reproductive capability and shorter generational gaps (Bezerra et al., 2009).…”

Ovelhas desafiadas no final da gestação: respostas comportamentais e reprodutivas de cordeiros

“…A não diferença quanto às médias de calcificação e seus baixos valores de escore também apontam que não houve situação de degeneração testicular com o passar dos meses (ÜLKER et al, 2005;GOULESTOU, 2017 (CIEŚLAK et al, 2015;NAZARI-ZENOUZ et al, 2016;RECABARREN et al, 2017). Neste caso o tratamento imposto durante a gestação não alterou a testosterona circulante no metabolismo dos animais.…”