Nitric oxide in pregnancy and lactation : hormonal regulation and fuctional significance

In female rats, the capacity for nitric oxide (NO) production within the hypothalamus is regulated by reproductive state and by the ovarian and peptidergic hormonal pattern that simulates late pregnancy. The first series of experiments described in this thesis examined the interaction of prolactin and oxytocin in upregulating nitric oxide synthase (NOS) activity and oxytocin gene expression within the hypothalamus in steroid-primed rats. Prolactin was found to upregulate NOS and this effect was mediated by oxytocin receptor activation. In addition, increased prolactin was associated with an increase in oxytocin mRNA within both the paraventricular (PVN) and supraoptic (SON) nuclei. The second set of experiments explored the inhibitory role of NO within the hypothalamic neurohypophysial system. The results demonstrated that NO modulated the activity of neurons in discrete nuclei in the hypothalamus and that this modulation was stimulus specific and varied with reproductive state. Central oxytocin administration induced more Fos expression within the SON and PVN in lactating than in nonlactating rat; but the opposite effect was seen following urethane administration. Inhibiting NO production increased Fos induction following central oxytocin administration in lactating rats whereas in nonlactating rats NOS inhibition decreased Fos-lir following both types of stimulation. The third series of experiments investigated a role for NO in milk ejections and the regulation of established maternal behavior. Data from these studies revealed that central inhibition of NO production disrupted pup retrieval and maternal aggression on both Day 4 and Day 10 of lactation. Together the experiments described in this thesis show that prolactin and oxytocin interact to upregulate NOS within the PVN and SON. Moreover, the increase in capacity to produce NO during lactation has a restraining effect on the activation of oxytocin neurons by oxytocin. Finally, NO has also been shown to play an important role in maternal retrieval and aggression

NADPH-d staining in the supraoptic and paraventricular nuclei increases in late pregnant and lactating rats and is influenced by ovarian steroids and central oxytocin levels

Previous research has demonstrated that staining for NADPH-diaphorase (NADPH-d) a histochemical marker for nitric oxide synthase is increased in the supraoptic (SON) and paraventricular (PVN) nuclei in late pregnancy. This work was extended to investigate whether increases in staining were evident at other times during pregnancy and lactation. The number of cells in the SON and PVN that stained for NADPH-d in rats on Day 4, 12, 16, and 22 of pregnancy and on Day 4, 12, and 20 of lactation was compared to that in virgin females. In other studies, the influence of ovarian hormones and central oxytocin infusion on NADPH-d staining in these nuclei was examined. Staining in the SON and PVN was compared among ovariectomized (ovex) animals exposed to either a steroid hormone regimen that mimics late pregnancy (estrogen (E) + progesterone (P) treatment followed by P removal), E alone, E + P, or cholesterol alone. A second study compared NADPH-d staining in ovex animals exposed to either chronic E or cholesterol treatment and infused with oxytocin or vehicle into the third ventricle for 7 days. On the appropriate day, all animals were perfused and the brains were processed for NADPH-d histochemistry. In both the SON and PVN the number of densely stained cells present on Days 12 and 22 of pregnancy and 4 and 12 of lactation was greater than that seen in virgin females. Both the steroid treatment that mimicked late pregnancy and chronic i.c.v. oxytocin infusion in E-primed animals increased NADPH-d staining in ovex animals. These data suggest that, in general, NADPH-d staining in the SON and PVN is increased at times when oxytocin cells in these areas are activated and that the hormonal state associated with late pregnancy is sufficient to up-regulate NADPH-d in these region

Harnessing Stakeholder Perspectives and Experience to Address Nutrition Risk in Community-Dwelling Older Adults

Community-dwelling, older adults have a high prevalence of nutrition risk but strategies to mitigate this risk are not routinely implemented. Our objective was to identify opportunities for the healthcare system and community organizations to combat nutrition risk in this population in the jurisdiction of Alberta, Canada. An intersectoral stakeholder group that included patient representatives was convened to share perspectives and experiences and to identify problems in need of solutions using a design thinking approach. Results: Two main themes emerged from the workshop: (1) lack of awareness and poor communication of the importance of nutrition risk between healthcare providers and from healthcare providers to patients and (2) the necessity to work in partnerships comprised of patients, community organizations, healthcare providers and the health system. Conclusion: Improving awareness, prevention and treatment of malnutrition in community-dwelling older adults requires intersectoral cooperation between patients, healthcare providers and community-based organizations

Nutrition Risk, Resilience and Effects of a Brief Education Intervention among Community-Dwelling Older Adults during the COVID-19 Pandemic in Alberta, Canada

Up to two-thirds of older Canadian adults have high nutrition risk, which predisposes them to frailty, hospitalization and death. The aim of this study was to examine the effect of a brief education intervention on nutrition risk and use of adaptive strategies to promote dietary resilience among community-dwelling older adults living in Alberta, Canada, during the COVID-19 pandemic. The study design was a single-arm intervention trial with pre–post evaluation. Participants (N = 28, age 65+ years) in the study completed a survey online or via telephone. Questions included the Brief Resilience Scale (BRS), SCREEN-14, a brief poverty screen, and a World Health Organization-guided questionnaire regarding awareness and use of nutrition-related services and resources (S and R). A brief educational intervention involved raising participant awareness of available nutrition S and R. Education was offered via email or postal mail with follow-up surveys administered 3 months later. Baseline and follow-up nutrition risk scores, S and R awareness and use were compared using paired t-test. Three-quarters of participants had a high nutrition risk, but very few reported experiencing financial strain or food insecurity. Those at high nutrition risk were more likely to report eating alone, compared to those who scored as low risk. There was a significant increase in awareness of 20 S and R as a result of the educational intervention, but no change in use. The study shows increasing individual knowledge about services and resources in the community is not sufficient to change use of these services or improve nutrition risk