title: Seasonal alterations in adrenocortical cell function associated with stress-responsiveness and sex in the eastern fence lizard (Sceloporus undulatus).
abstract: We characterized steroidogenic properties of dispersed adrenocortical cells from field-active male and female eastern fence lizards (Sceloporus undulatus) to investigate whether alterations in cell function could, in part, explain seasonal variation in baseline and stress-induced plasma corticosterone (B). Lizards were collected during the breeding and postbreeding seasons and shortly prior to hibernation. Dispersed cells in vitro produced B, aldosterone (ALDO), and progesterone in response to 8-Br-cAMP, 25-(OH)cholesterol, adrenocorticotropin (ACTH; as little as 100 fM), and angiotensin II. Maximal progesterone, B, and ALDO responses to ACTH were roughly 1000%, 500%, and 100% greater than corresponding basal values. Angiotensin II was an effective steroidogenic stimulant but much less so than ACTH. Corticosteroid production exhibited considerable steroid-specific variation among seasons. Maximal ACTH-induced B production was lower in the postbreeding season than at either of the other two measurement points, essentially opposite to the pattern for ALDO. Males and females generally produced B at similar rates, but ALDO and progesterone showed numerous sex differences that usually covaried between the two steroids. Cellular sensitivity to 25-(OH)cholesterol and angiotensin II showed few sex differences or seasonal changes. In contrast, sensitivity to ACTH decreased markedly from the breeding to the postbreeding season in males, corresponding to the decrease in stress-responsiveness, and in both sexes was considerably lower prior to hibernation than during the breeding season. Under some conditions, plasma B may be limited by the production capacity of adrenocortical cells. In summary, seasonal variations in body condition, reproductive activity, and baseline and stress-induced plasma B may be attributed at least in part to alterations in adrenocortical cell steroidogenic function.
authors.affiliation: Department of Cell Biology, University of Medicine and Dentistry of New Jersey, School of Osteopathic Medicine, Stratford 08084, USA.
authors.forename: Rocco V
authors.initials: RV
authors.lastname: Carsia
authors.forename: Henry
authors.initials: H
authors.lastname: John-Alder
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000302:Adrenal Cortex / Q000166:cytology / Q000502:physiology*; D000305:Adrenal Cortex Hormones / Q000097:blood*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000450:Aldosterone / Q000097:blood; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D003345:Corticosterone / Q000097:blood; D005260:Female; D006605:Hibernation / Q000502:physiology; D006888:Hydroxycholesterols / Q000494:pharmacology; D008116:Lizards / Q000502:physiology*; D008297:Male; D011374:Progesterone / Q000097:blood; D012621:Seasons; D013315:Stress, Psychological / Q000503:physiopathology*
chemical_list: D000305:Adrenal Cortex Hormones; D006888:Hydroxycholesterols; D000804:Angiotensin II; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000450:Aldosterone; D011374:Progesterone; C007997:25-hydroxycholesterol; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone