RESUMO
In mammals, pregnancy induces a transient and extensive degeneration of uterine sympathetic innervation. We used the models of unilateral oviduct ligation and in oculo myometrium transplant in pregnant rats to address the role of stretching forces and/or hormone milieu in the loss of sympathetic innervation. The sympathetic fibres of the uterine horn and in oculo myometrial transplants were quantified on tissue sections processed by the glyoxylic acid technique. In normal pregnant rats, the density of uterine horn innervation was significantly reduced at late pregnancy and recovery took place during post partum. The empty horn of pregnant rats showed no significant changes in density of myometrial innervation during pregnancy or post partum. In oculo myometrial transplants were organotypically reinnervated in virgin animals. When the transplants were exposed to gestational hormonal milieu, few or no fibres were observed to the end of pregnancy; however, a significant increase at post partum was observed. Results showed that both the effects of stretching and the hormone milieu derived from the fetus-placenta complex play a role as inductors of changes on sympathetic myometrial innervation during pregnancy and support the idea that immature muscular uterine fibres are more susceptible to the effects of pregnancy than those originating from adult animals.
Assuntos
Período Pós-Parto , Sistema Nervoso Simpático/anatomia & histologia , Útero/inervação , Animais , Feminino , Glioxilatos , Histocitoquímica , Músculo Liso/inervação , Miométrio/anatomia & histologia , Miométrio/inervação , Miométrio/transplante , Norepinefrina/análise , Gravidez , Ratos , Ratos Wistar , Sistema Nervoso Simpático/químicaRESUMO
The acute phase of the Trypanosoma cruzi infection induces damage of the heart sympathetic nerve terminals in rats. The participation of the radiosensitive leukocytes in this process was assessed in young rats submitted to gamma irradiation 1 day before infection with T. cruzi, Y strain. Gamma irradiation increased the heart noradrenergic denervation evaluated at day 12 of infection by histochemical and electron-microscopic methods. The presence of numerous macrophages with ultrastructural features of activation and a significant rise in the myocardial parasitism suggest the involvement of radioresistant macrophages or parasite factors, or both, on the damage of the nerve terminals.
Assuntos
Cardiomiopatia Chagásica/imunologia , Leucócitos/efeitos da radiação , Sistema Nervoso Simpático/imunologia , Sistema Nervoso Simpático/parasitologia , Animais , Formação de Anticorpos/efeitos da radiação , Feminino , Átrios do Coração/inervação , Átrios do Coração/parasitologia , Imunidade Celular/efeitos da radiação , Leucócitos/imunologia , Leucócitos/parasitologia , Microscopia Eletrônica , Miocárdio/citologia , Miocárdio/imunologia , Miocárdio/ultraestrutura , Norepinefrina/análise , Ratos , Ratos Sprague-Dawley , Sistema Nervoso Simpático/químicaRESUMO
Sympathetic nerves to the enlarged fetus-containing region of the uterus undergo degenerative changes during late pregnancy and show slow regrowth after parturition. It is not known whether this unusual response of sympathetic nerves to smooth muscle hypertrophy is due to the sensitivity of short adrenergic neurons to hormonal changes, or whether the nerves respond to changes in the neurotrophic capacity of the target. We have investigated this question using in oculo transplantation. Small pieces of myometrium from the uterine horn of virgin guinea pigs, or from the region previously occupied by the placenta and fetus in postpartum guinea pigs, were transplanted into the anterior eye chamber. After 3 wk in oculo, the pattern of reinnervation of the transplants was assessed on whole mount stretch preparations stained for tyrosine hydroxylase. The histology of the transplants was examined in toluidine blue-stained semithin sections. Myometrial transplants from virgin donors and uterine artery transplants from both virgin and postpartum donors became organotypically reinnervated by sympathetic fibres from the host iris. In contrast, sympathetic nerves did not reinnervate myometrial transplants from postpartum donors, although they approached the transplants and became distributed in the surrounding connective tissue. All transplanted tissues showed a normal histological appearance. Both the myometrium and uterine artery from postpartum donors retained a hypertrophic appearance after 3 wk in oculo. We interpret these results to indicate that the degeneration of sympathetic nerves in late pregnancy, as well as their slow regrowth to the uterus after delivery, may be due to changes in uterine smooth muscle rather than a particular sensitivity of short adrenergic neurons to hormonal changes.