Dehydroepiandrosterone and cortisol concentrations in the cerebrospinal fluid of dogs

Abstract

Concentrations of cortisol, dehydroepiandrosterone and dehydroepiandrosterone-sulfate were measured by performing radioimmunoassay of the cerebrospinal fluid of 68 dogs diagnosed with idiopathic epilepsy or inflammatory, degenerative, or non-neurological disease. No steroid concentration differences were found among diagnoses. Dehydroepiandrosterone and dehydroepiandrosterone-sulfate concentrations were higher in males than in females and dehydroepiandrosterone-sulfate decreased with increasing age. No sex or age effects were observed on cortisol or hormone ratios. Although limited to a relatively small sample, our results show sex-and age-dependent variations in these neurosteroid concentrations in cerebrospinal fluid. The role of such variations in the pathophysiology of the dog brain warrants further investigation. Keywords: cerebrospinal fluid, dehydroepiandrosterone, dogs, hydrocortisone, sexIn humans, plasma levels of dehydroepiandrosterone (DHEA) and its circulating storage form DHEA sulphate (DHEA-S) are dependent on sex, higher concentrations being found in adult men than women. In both sexes, however, concentrations decline during ageing, falling to 5-30% of their peak value by the eight decade [8]. A similar age-related decline is also observed in the cerebrospinal fluid (CSF), but there seems to be no difference between sexes at this level [6]. Since cortisol levels increase with ageing, higher cortisol/ DHEA ratios are found in both plasma and CSF of elderly people [6]. In adult dogs, plasma DHEA is much higher in males than in females and only in the latter there is a clear age-related decline; at the same time, no age-related differences have been found for plasma cortisol concentrations in this species [12]. The dog's body size can affect steroid concentrations, as higher plasma cortisol concentrations have been observed in small than in large dogs [13].Since the first description of its synthesis in the central nervous system (CNS) [1], interest in DHEA has grown in view of its role as a neuroactive steroid. DHEA exerts neurotrophic and neuroprotective functions, antagonizing detrimental effects of glucocorticoids, whose concentrations in both blood and CSF have been correlated with functional and morphological neural deficits [9,16]. The ratio between cortisol and DHEA and DHEA-S concentrations is therefore considered crucial in the pathophysiology of neurodegenerative processes and other neurologic diseases. For instance, decreased DEHA-S and DHEA-S to cortisol ratio have been associated with agerelated neurodegeneration and cognitive decline and epilepsy [4,5]. Conversely, the concentrations of both DHEA-S and cortisol increase in patients with inflammatory neurological diseases, compared to non-inflammatory ones [7]. Dogs develop age-related lesions and functional deficits of the CNS analogous to those of humans and are considered a good model of age-related neurodegenerative processes [15]. A syndrome characterized by abnormal behaviours and believed to be consequence of such neur...

Do Dehydroepiandrosterone (DHEA) and Its Sulfate (DHEAS) Play a Role in the Stress Response in Domestic Animals?

“…We are aware that both Purkinje neurons and oligodendrocytes of the dog cerebellar cortex contain steroidogenic enzymes (e.g., 3βHSD) (74). Both DHEA and DHEAS were detected in the cerebrospinal fluid (CSF) of dogs, concentrations of both compounds were higher in males than in females, and DHEAS decreased with increasing age (75).…”