Post-testicular sperm maturation and identification of an epididymal protein in the Japanese quail (Coturnix coturnix japonica).

The role of the avian epididymis in post-testicular development and capacitation was examined to assess whether avian spermatozoa undergo any processes similar to those characteristic of mammalian sperm development. We found no evidence of a need for quail sperm to undergo capacitation and 90% of testicular sperm could bind to a perivitelline membrane and acrosome react. However, computer-assisted sperm analysis showed that 20% of testicular sperm from the quail were capable of movement and only about 12% of the motile sperm would have a curvilinear velocity greater than the mean for sperm from the distal epididymis. Nevertheless, epididymal transit was associated with increases in mean sperm velocity and the proportion of motile sperm. Together, these findings explain why earlier workers have achieved some fertilizations following inseminations of testicular spermatozoa and also demonstrate the need for some epididymal maturation of avian spermatozoa. Analysis of the electrophoretic profile of quail epididymal luminal proteins revealed that only one major protein (∼16 kDa) is secreted by the epididymis and it was virtually the only protein secreted by the ipsilateral epididymis following unilateral orchidectomy. Mass spectrometry showed that this protein is hemoglobin; this finding was confirmed using anti-hemoglobin antibodies. It is suggested that hemoglobin may support sperm metabolism in the quail epididymis, aid in motility, and/or serve as an antioxidant.

Prenatal endotoxin exposure alters behavioural pain responses to lipopolysaccharide in adult offspring.

Evidence suggests that exposure to bacterial endotoxin in early life can alter the production of pro-inflammatory cytokines in later life. This phenomenon may have significant consequences for pain and pain related behaviours as pro-inflammatory cytokines heighten pain sensitivity. This association has yet to be examined. As such, the aim of the present study was to characterize pain behaviours in adult rat offspring following prenatal endotoxin (PE) exposure. Pregnant F344 rats received endotoxin (200microg/kg, s.c.) or saline on gestational days 16, 18 and 20. Pain thresholds were assessed in the adult PE offspring (n=23) and control offspring (n=24) prior to and 4h following administration of lipopolysaccharide (LPS; 100microg/kg, s.c.). Three assays of pain were employed - the hot plate, tail immersion and von Frey tests. Results demonstrated sex-specific effects of prenatal endotoxin on the offspring, with PE males displaying unaltered pain thresholds on the von Frey test post-LPS administration (p<0.01), while male control offspring (n=24) displayed the expected hyperalgesia. Male PE offspring also displayed increased pain thresholds on the tail immersion test (p<0.01), while no change in pain sensitivity was observed in control males following LPS exposure. No difference in response was observed between the female PE and control offspring on the von Frey test, however PE female offspring displayed increased thresholds on the tail immersion test compared to baseline - an effect not observed in the control female offspring. Pain sensitivity on the hot plate test was unaffected by prenatal exposure to endotoxin. These data suggest that prenatal exposure to products associated with bacterial infection have the capacity to alter pain responses, which are evident in the adult offspring.

Innate immune dysfunction in the neonatal rat following prenatal endotoxin exposure.

The efficacy of the neonatal innate immune system to respond to bacterial exposure following maternal infection is of great interest, as the neonatal period is one of relative immune immaturity, and is associated with high rates of morbidity and mortality. This study aimed to determine the response to an in-vivo endotoxin challenge in the neonatal period following prenatal exposure to bacterial endotoxin. Pregnant Fischer 344 dams received either endotoxin or the vehicle on gestational days 16, 18 and 20 (term=23 days). The neonatal (5 day) offspring were then exposed to an endotoxin challenge; blood was collected at baseline or at 4 h for analysis of blood cell counts, corticosterone, TNF alpha and IL-1 beta, levels. The neonatal rat pups responded to the challenge with significantly reduced corticosterone, TNF alpha and IL-1 beta levels compared to controls (p<0.003). Monocyte, neutrophil and eosinophil counts were also significantly reduced in the prenatal endotoxin offspring compared to controls (p<0.02). While the immune system is functionally immature in the neonatal period, these results suggest that prenatal infection may further reduce the capacity of the innate neonatal immune system to respond to endotoxin, leaving offspring more vulnerable to pathogenic invasion in neonatal life.

Prenatal exposure to a pro-inflammatory stimulus causes delays in the development of the innate immune response to LPS in the offspring.

Growing evidence suggests that maternal health during the prenatal period is a critical determinant of adult immuno-competence. This study aimed to characterise the innate immune response to bacterial exposure in rat offspring following maternal exposure to a pro-inflammatory stimulus. The offspring's innate immune responses were investigated at four developmental timepoints in the rat by determination of immune cell subtypes and TNF-alpha and IL-1beta response to in-vivo LPS exposure. The pre-weaned offspring of exposed dams demonstrated no immune response to the LPS challenge, whereas control offspring responded with a typical elevation in cytokine levels. In pubescence no differences were observed between the responses of the control and exposed offspring. In adulthood and senescence, offspring of endotoxin treated dams had significantly less monocytes in circulation than control offspring and differential sex effects were only evident in these older animals. The developmental profile of immune functioning following prenatal immune activation has not previously been demonstrated. This study highlights the prenatal period as one of importance in determining later immune function.

Modelling prenatal bacterial infection: functional consequences of altered hypothalamic pituitary adrenal axis development.

Prenatal exposure of animals to bacterial endotoxin is an experimental model of systemic maternal infection in the human pregnancy. Previous studies in the rat have demonstrated that such exposure is associated with long term alterations to hypothalamic pituitary adrenal (HPA) axis development. Typically, these animals display an elevated HPA response to stress in adulthood. As neural development is more similar in the human and the guinea pig than the rat, this study adopted a guinea pig model of pregnancy to explore the effects of endotoxin exposure on the HPA axis in the offspring. The offspring of dams exposed to endotoxin exhibited an attenuated cortisol response to the novel environment stress in the weaning period. The degree to which this cortisol response was both buffered by the mother's presence, and habituated to on repeated exposure, differed significantly between the prenatal treatment groups. In adulthood, a diminished cortisol response to the immune challenge was only evident in the female offspring, while both male and female offspring exhibited altered febrile responses. The results of the present study indicate that prenatal bacterial exposure in the guinea pig results in offspring with lower cortisol responses to stress in later life. These findings contrast past research that has used the rat to model pregnancy. As such, the use of the guinea pig to model infection may provide a useful alternative model of human pregnancy to explore programming effects.

Early life host-bacteria relations and development: long-term individual differences in neuroimmune function following neonatal endotoxin challenge.

Neonatal animals have a proportionately greater risk, relative to the adult animal, of developing a bacterial infection. Research has revealed that such infections can influence biological processes long after the actual infection has been resolved. Indeed, studies examining the long-term alterations induced by early-life infection, simulated using endotoxin, have indicated that some aspects of the systemic inflammatory response in the adult animal are susceptible to modification. Available evidence suggests that altered inflammatory activities observed in the neonatally endotoxin challenged adult may be the result of potentiated hypothalamic pituitary adrenal (HPA) activity, specifically increased corticosterone production. Few studies, however, have examined whether altered corticosterone production is actually associated with changes in systemic inflammation in the neonatally endotoxin challenged adult animal. The aim, therefore, of the current study was to simultaneously examine the relationship between altered inflammatory activities and corticosterone production in the neonatally endotoxin challenged adult rat. Our findings demonstrate no significant differences exist between adults neonatally treated with saline or endotoxin in terms of their production of corticosterone following endotoxin challenge. While not appearing to influence the production of corticosterone neonatal endotoxin challenge did result in a marked attenuation in the adult's febrile response following endotoxin challenge. Interestingly, circulating levels of IL-1beta and TNF-alpha were found to be equivalent in neonatal treatment groups following endotoxin administration in adulthood, indicating that the reduction in fever was unlikely to be the result of altered pro-inflammatory cytokine production. Further, no differences were found between neonatal treatment groups in net food consumption, water consumption or weight loss following endotoxin challenge in adulthood. Collectively, these findings demonstrate that neonatal endotoxin challenge does not affect a blanket down regulation of inflammatory processes but rather appears to induce highly specific alterations in the adult male Fischer-344 rat.