Comparative analysis of reproductive cycles in female Persian gazelle (Gazella subgutturosa subgutturosa) (Central Asia) and sand gazelle (Gazella subgutturosa marica) (Arabian Peninsula).

This study was conducted at the Bukhara breeding centre (Ouzbekistan, Central Asia) on Persian gazelles (Gazella subgutturosa subgutturosa) and at Thumammah (Saudi Arabia) on sand gazelles (Gazella subgutturosa marica). Plasma prolactin (PRL) and progesterone were determined in groups of females. Because these females were under two different photoperiods (20 degrees N in Saudi Arabia and 40 degrees N in Uzbekistan), some Persian females were treated with melatonin implants. Both groups of females living in natural environment in Uzbekistan and in Saudi Arabia exhibited an estrus (autumn and early winter) and an anestrus season (spring and summer). Both groups of females exhibited estrous and anestrous seasons. The estrous season was shorter in females from Uzbekistan. During the anestrous season, progesterone concentrations remained at basal levels in Persian gazelles (Uzbekistan) while in sand gazelles (Saudi Arabia) hormonal concentrations were higher than in Persian gazelles until August and decreased to similar concentrations in September-October. Moreover, the pattern of PRL significantly differed in the two groups. Persian gazelles exhibited a clear seasonal pattern with significantly high levels of PRL in June whereas in the sand gazelle PRL did not rise significantly in summer and fluctuated widely. Melatonin treatment significantly depressed PRL concentrations but did not affect the length of the estrous season in Persian gazelles, suggesting that the reproductive cycle was entrained by an endogenous rhythm.