Adrenal-pituitary-gonadal relationships and ejaculate characteristics in captive leopards (Panthera pardus kotiya) isolated on the island of Sri Lanka

Abstract

In Study 1, semen was collected using a standardized electroejaculation procedure. Males (N = 8) produced ejaculates with a high incidence of sperm abnormalities (77 ± 3.3%). After electroejaculation under anaesthesia, serum cortisol concentrations increased (P < 0.05), while testosterone concentrations decreased (P < 0.05) and LH and FSH concentrations were unchanged (P > 0.05) over a 2-h bleeding period. In Study 2, male and female leopards were bled at 5-min intervals for 3 h and given (i.v.): (1) saline (N = 2/sex); (2) GnRH (1 μg/kg body weight) 30 min after the onset of sampling (N = 5/sex); or (3) ACTH (250 μg) at 30 min followed by GnRH 1 h later (N = 5/sex). Basal concentrations of serum LH, FSH and cortisol were comparable (P > 0.05) between male and female leopards. After GnRH, peak LH concentrations were 2-fold greater (P < 0.05) in males than females while FSH responses were similar. In males, testosterone concentrations increased 2-3-fold following GnRH. After ACTH, serum cortisol concentrations doubled within 15 min in both sexes. Administration of ACTH 1 h before GnRH did not affect GnRH-induced LH or FSH release (P > 0.05); however, testosterone secretion was only 30% of that observed after GnRH alone (P < 0.05). We conclude that (1) the high incidence of sperm abnormalities in the leopards of Sri Lanka may be related to parallel findings of genetic homozygosity; and (2) decreases in basal and GnRH-stimulated testosterone secretion were related to increases in serum cortisol afte electroejaculation or ACTH and were not associated with changes in pituitary gonadotrophin secretion.