Effect of neonatal thymulin gene therapy on reproductive alterations of female adult nude mice.

REGGIANI PC; FLAMINI MA; ZUCOLILLI GO; DARDENNE M; GOYA RG; BARBEITO CG

Aguas de Lindoia, Brasil

Congreso; Encontro Nacional de Patologia Veterinária; 2009

Associação Brasileira de Patologia Veterinária (ABPV)

The thymus produces a number of bioactive peptides including the hormone thymulin, which modulates the proliferation and differentiation of T cells. Besides, there is emerging evidence that thymulin has hypophysiotropic activity and is involved in reproductive maturation. Thus, congenitally athymic (nude) female mice show reduced levels of circulating gonadotropins and a number of reproductive derangements after puberty. It was therefore of interest to determine whether neonatal thymulin gene therapy (NTGT) can prevent the reproductive derangements of adult nude mice. Initially, we constructed an adenoviral vector (RAd-FTS) expressing a synthetic gene for thymulin and showed that NTGT restores serum thymulin and prevents gonadotropin deficiency in adult nudes. In the present study we aimed at determining whether NTGT in female nudes can prevent the typical changes found in the reproductive organs of this mutant. RAd-FTS or RAd-GFP (control vector expressing green fluorescent protein) were i.m. injected (108 pfu) to newborn female nu/+ and nu/nu (athymic) mice. From day 22 on, the onset of fertility was assessed by monitoring the day of vaginal opening. At 70 days of age, mice were bled and sacrificed; ovaries, uteri and brain were submitted to histomorphometric analysis. The reproductive organs were processed and embedded in paraffin and stained with Haematoxylin and eosin. The brain was processed for the characterization of gonadotropin-releasing horomone (GnRH)-producing cells using immunohistochemistry. Serum thymulin was measured by a bioassay. Progesterone and estrogen levels were measured by RIA. The NTGT in athymic mice restored their serum thymulin levels (256±80,9 vs 8±0,5 (control) fg/ml (p<0,01)). Furthermore, NTGT prevented the typical deficiency in the number of secondary (p<0.01) and tertiary (p<0.15) follicles, and of corpora lutea (p<0.05). The NTGT also prevented the increase in the number of atretic follicles typical of athymic mice (nu/nu treated vs nu/nu controls, P<0.001). The typical serum E2 deficiency of adult nu/nu females was partially prevented by NTGT. The NTGT also preventied the typical delay of vaginal opening in nudes (p<0.05). The height of uterine epithelium, the serum concentration of progesterone and the numbers of GnRH neurons were increased in the NTGT nude animals versus control nudes, but the differences were not significant. We conclude that thymulin plays a relevant physiological role in the thymus-hypothalamo-gonadal axis during early life and possibly, also later. NTGT in nude female mice prevents most of the typical alterations in the reproductive axis that typically occur in this mutant.