A Feasibility Assessment of Measuring Acceptance and Adherence to a Plant-Based (Vegan) Diet in a Cardiology Clinic.

There are numerous changes in the body and brain that occur during pregnancy and lactation that enable a mother to successfully raise their offspring. The suppression of stress responses is one adaptation that develops during pregnancy in humans, sheep and rodents and persists through lactation in all of these species. While pregnancy-induced adaptations have been shown to occurs at multiple levels of the stress axis, alterations in the function of hypothalamic corticotropin-releasing hormone (CRH) neurons are thought to be particularly important. CRH neurons in the paraventricular nucleus (PVN) of the hypothalamus are the master controllers of the hypothalamic-pituitary-adrenal (HPA) axis. These neurons control the release of adrenocorticotropic hormone (ACTH) from the pituitary gland and the subsequent release of glucocorticoid stress hormones from the adrenal gland. In addition to their neuroendocrine role, these neurons also control arousal state and stress-related behaviours. In many situations, it is advantageous to coordinate the neuroendocrine and behavioural responses to stress. However, because stress hormone secretion from the pituitary and adrenal gland can be regulated independently from CRH neural activity, there may exist situations where CRH neuron activity and endocrine output are dissociated. During lactation, it is well established that stress-evoked corticosterone release is suppressed in rats and mice. Past studies have also reported that mRNA expression in the PVN is reduced during lactation and that stress-induced cfos expression in the PVN is also reduced. These findings are consistent with the hypothesis that reduced CRH neuronal activity is important for the reduced responsiveness of the HPA axis during lactation. Reduced CRH neural activity is proposed to be adaptive, as central injections of CRH impedes pup nursing and protective behaviours and has also been associated with pup neglect and infanticide. Likewise, chemogenetic activation of CRH neurons in the PVN has been shown to inhibit maternal behaviour. While there is a general agreement that the HPA axis is suppressed during motherhood, evidence for reduced CRH neuron excitability is only indirect and comes from whole PVN mRNA measurements. For this reason, we set out to record PVN CRH neuron activity in vivo from freely behaving virgin and lactating mice under both basal and stress states. We also set out to determine how CRH neuron responses to pup cues change between virgin and lactating states.