Low concentrations of the polyamines putrescine (0.01-0.2 μg/ml medium), cadaverine (0.2 μg/ml), spermine (1.0 μg/ml), spermidine (1.0 μg/ml) and agmatine (1.5 μg/ml) did not enhance the release of FSH from anterior pituitaries of male rats incubated in vitro. All the polyamines tested were equally ineffective when incubated with pituitaries in the presence of hypothalamic tissue. In contrast, highly purified porcine FSH-releasing hormone1 (FSH-RH) in doses as low as 0.001-0.003 μg/ml medium significantly stimulated FSH release by pituitaries from normal intact male rats, ovariectomized rats pretreated with estrogen and progesterone, and castrated rats pretreated with testosterone propionate. These in vitro methods can be used successfully to detect FSH-RH activity in various stages in the purification of the extracts. The results clearly demonstrate that the polyamine substances tested do not represent the primary physiological FSH-RH.
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