Altered androstenedione to testosterone ratios and LH concentrations during musth in the captive male Asian elephant (Elephas maximus)

Abstract

Greater concentrations of androstenedione than testosterone were usually present during periods of non-musth in plasma collected weekly for various periods up to 2 years in 8 male Asian elephants (4-35 years of age). For the 6 males that exhibited musth the androstenedione/testosterone ratio shifted greatly in favour of testosterone. The severity of musth was assessed weekly using a scale of 1 to 5 for each of 8 behavioural traits including urine dribbling, temporal gland secretion and aggression. A significant correlation (P less than 0.05) was noted between plasma testosterone concentrations and the musth score value in 5 of 6 musth episodes. Brief shifts in the ratio of two androgens when testosterone predominated (n = 106) were seen during the non-musth period in 3 of the males studied continuously for 2 years. In 82% of these instances, stimuli of a sexual or aggressive nature had occurred in the preceding 48 h (chi 2, P less than 0.01). A heterologous bovine assay was used to measure LH values in plasma collected every 15 min for 12 h. Increases in testosterone concentrations followed pulsatile increases in plasma LH concentrations during 7 non-musth periods in 4 animals. Apart from pulse frequency, increases in the variables describing pulsatile LH secretion were seen in 2 strong musth and 2 mild musth episodes compared to non-musth values. A strong musth, however, was characterized by a much greater increase in pulsatile testosterone secretion than was a mild musth and which may be a function of the duration of musth.

A Surge-Like Increase in Luteinizing Hormone Preceding Musth in a Captive Bull African Elephant (Loxodonta africana)

“…Musth occurrence can be random, with many elephants exhibiting multiple episodes per year [3], and more predictable annual characteristics [4,8,11,13] in both male Asian and African elephants. The wellestablished association between high testosterone secretion and musth was confirmed in previous studies [6,8,10,15,[19][20][21]24]. The secretory pattern of inhibin in male elephants has never been reported before.…”

“…73(3): 379-383, 2011 Musth is a unique phenomenon that occurs either annually or semiannually in adult male African (Loxodonta africana) [7,16,17] and Asian (Elephas maximus) elephants [5,11]. During musth, male elephants have elevated levels of androgens, especially androstenedione and testosterone [1,6,7,10,15,18,20,21,24]. Musth bulls were reported to have elevated levels of luteinizing hormone (LH) in both African [1] and Asian [15] species.…”

“…During musth, male elephants have elevated levels of androgens, especially androstenedione and testosterone [1,6,7,10,15,18,20,21,24]. Musth bulls were reported to have elevated levels of luteinizing hormone (LH) in both African [1] and Asian [15] species. Secretory patterns of follicle stimulating hormone (FSH) and immunoreactive (ir-) inhibin in male elephants have never been reported before.…”

Testosterone secretion, musth behaviour and social dominance in captive male Asian elephants living near the equator

“…Musth appears to be similar to rutting behaviour in ungulates (Poole, 1987) and is associated with periodic increases in testosterone secretion (Jainudeen et al, 1972a; Hall-Martin and van der Walt, 1984; Cooper et al, 1990; Niemuller and Liptrap, 1991). During musth, males spend less time feeding, leave the bachelor herd, wander long distances in search of females in oestrus, become aggressive towards other males, vocalise with infrasound, produce copious secretions from the enlarged temporal glands and drip urine from the prepuce.…”

Musth in Elephants

“…Flanagan and Flanagan (1983) observed a reduction in aggressiveness in castrated bull elephant. Cooper et al (1990), Niemuller and Liptrap (1991) had stated that increased aggressive nature in musth is due to increased androgen level. Work done by Chandrasekharan and Cheeran (1996) showed treatment with antiandrogen namely Flutamide @ 5000 mg and 7500mg, haloperidole @ 100mg and potassium iodide @ 20gm per elephant administered orally once daily for a continuous period of three days, was very effective in controlling aggressive behaviour and other musth symptoms in captive elephants during their pre musth and last phase of violent musth.…”