Does time of day predict stress resilience/sensitivity across species?

Background: Evidence is emerging that the timing of a stressful challenge in relation to the individualʼs natural rhythm of hormone secretion, could be influencing the genomic response to stress, and resultant stress coping ability (Mifsud et al., 2021; Sterina et al., 2022). Studying adaptive responses to stress is important in order to understand processes of stress adaptation, resilience and the development of stress-related disorders which can have a significant impact on an individualʼs welfare.

Endogenous glucocorticoid hormones are secreted by the adrenal glands of mammals, often in a circadian manner with maximal levels of secretion peaking during the organism’s active phase and lower levels occurring during rest. In some species this occurs in a monophasic manner (diurnal, nocturnal species) but some species display multiphasic patterns (crepuscular, cathemeral/metaturnal).

Aims and objectives: This project will seek to determine the relevance of the endogenous corticosteroid level at the time of stress exposure for stress coping ability across a range of species with different activity patterns, including companion animals and livestock.

Methods: Stress coping ability will be measured in an interdisciplinary way, utilising the most appropriate method of study for each species in relation to the species-specific stressors they face. This will involve a combination of behavioural studies, owner feedback questionnaires, physiological measurements and molecular analyses. Examples of commonly encountered stressors encountered for companion animals include vet or grooming visits, fireworks, kennel/cattery stays. For livestock stressors included castration, horn debudding and transportation.

These ‘real worldʼ responses will be supported by experiments in vivo to understand the underlying (epi-)genomic and mechanistic consequences of endogenous glucocorticoid hormone levels on stress responses regulating adaptive behaviour, and the impact this has on an individual’s stress coping ability.

There will also be the opportunity to develop bioinformatic skills by integrating existing publicly available datasets of relevance (including our own) into ongoing analysis. This project has the potential to enhance animal welfare by developing recommendations regarding the timing of stressful experiences to minimise the negative impact of a stressor.

Key references:

Mifsud KR, Kennedy CLM, Salatino S, Sharma E, Price EM, Haque SN, Gialeli A, Goss HM, Panchenko PE, Broxholme J, Engledow S, Lockstone H, Cordero Llana O, Reul JMHM. Distinct regulation of hippocampal neuroplasticity and ciliary genes by corticosteroid receptors. Nat Commun. 2021 Aug 6;12(1):4737. doi: 10.1038/s41467-021-24967-z. PMID: 34362910; PMCID: PMC8346558.

Sterina E, Michopoulos V, Linnstaedt SD, Neylan TC, Clifford GD, Ethun KF, Lori A, Wingo AP, Rothbaum BO, Ressler KJ, Stevens JS. Time of trauma prospectively affects PTSD symptom severity: The impact of circadian rhythms and cortisol. Psychoneuroendocrinology. 2022 Jul;141:105729. doi: 10.1016/j.psyneuen.2022.105729. Epub 2022 Mar 19. PMID: 35413575; PMCID: PMC9250148.

Supervisors:

Primary supervisor: Dr Karen Mifsud ([email protected])

Secondary supervisor: Prof. Hans Reul ([email protected])

Start date: Sept 2025

How to apply: See How to apply – SWBiosciences Doctoral Training Partnership

Candidate requirements:

See Eligibility – SWBiosciences Doctoral Training Partnership.

Standard University of Bristol eligibility rules for PhD admissions also apply. Please visit PhD Veterinary Sciences

 Contacts: Contact the lead supervisor [email protected] if you have queries about the project. For queries about the SWBio DTP scheme contact [email protected]