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R. M. LIPTRAP and J. I. RAESIDE

It is well established that cryptorchidism is associated with degeneration of the seminiferous tubules, but there is less certain knowledge concerning the internal secretory capacity of the abdominal testis. Although unilaterally and bilaterally cryptorchid boars are able to excrete dehydroepiandrosterone (DHA) and oestrogens in amounts comparable to those of normal boars (Liptrap & Raeside, 1970), the abdominal testes of such animals show a limited response to gonadotrophin stimulation (Liptrap & Raeside, 1971). The purpose of the present study was to determine if the higher abdominal temperature was responsible, at least in part, for the limited response of the cryptorchid testis to stimulation by hcg, as reflected in the urinary excretion of DHA and oestrogens.

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R. M. LIPTRAP and J. I. RAESIDE

Summary.

Urinary excretion of dehydroepiandrosterone (DHA) and oestrogens was determined in five bilaterally cryptorchid boars and four unilaterally cryptorchid boars. Similar determinations were carried out in two boars made cryptorchid through surgery. The DHA and oestrogen values for the cryptorchid animals were comparable to normal boars of a similar age. These results suggest that the cryptorchid testes of the boar are capable of producing normal amounts of testicular steroid hormones.

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R. M. LIPTRAP and J. I. RAESIDE

Summary.

Luteinizing hormone (lh) activity in blood was assessed by the ovarian cholesterol depletion (ocd) method and oestrogens were estimated chemically in the urine of seven sows before and during oestrus. In three sows, peritoneal cannulation permitted the time of ovulation to be related to lh and oestrogen determinations. The findings suggest a marked elevation of blood lh activity coincident with a peak of urinary oestrogen excretion, and occurring 40 to 48 hr before the time of ovulation.

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R. M. LIPTRAP and J. I. RAESIDE

Summary.

Urinary levels of DHA and oestrogens were determined in normal, unilaterally and bilaterally cryptorchid boars and in such animals following hemicastration or treatment with hcg. Removal of one testis from normal boars or the abdominal testis from unilaterally cryptorchid boars did not appreciably alter the urinary levels of DHA and oestrogens. Removal of the scrotal testis of unilaterally cryptorchid boars or one abdominal testis of bilaterally cryptorchid boars resulted in a significant drop in urinary steroid values. Except for one boar, DHA returned to within control levels in 2 months while oestrogen values were significantly lower in two animals and significantly higher in one animal at 2 months. hcg treatment caused a highly significant increase in DHA and oestrogen excretion in a normal boar and a unilaterally cryptorchid boar with a scrotal testis remaining after hemicastration. Boars with bilateral cryptorchid testes and a boar with an abdominal testis remaining after hemicastration showed a limited response to hcg injections. The results suggest that the cryptorchid testis of the pig is able to compensate for the loss of the contralateral gonad but the limit of response to gonadotrophin is very much lower and the time of response is slower than that exhibited by the scrotal testis.

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C. A. Niemuller and R. M. Liptrap

Summary. 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 < 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 the 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 (x 2, P < 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.

Keywords: elephant; musth; androgens; luteinizing hormone