ACTIVATION OF THE ADENOHYPOPHYSIS BY INTRAVENOUS INJECTIONS OF EPINEPHRINE IN THE ATROPINIZED RABBIT

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Abstract
A study employing 91 rabbits reveals that atropine sul-fate, in doses adequate to block copulation-induced ovulation, prevents the fatal effects of twice-lethal intraven. dosages of either acetylcholine-eserine (practically complete protection) or epinephrine (survival in about half of the cases). The atropine protection against epinephrine poisoning is short-lived, but survivors of atropine-epinephrine admn. are protected for some days against the lethal effects of further large doses of epinephrine. The prolonged protection is apparently a function of the initial epinephrine itself, acting as an adrenergic blocking agent. These data raise the question as to whether atropine blocks the coital stimulus by virtue of anti-adrenergic properties. Intraven. epinephrine (1 mg./kg.) stimulated the release of luteinizing hormone in 5 out of 7 mature, estrous, estrogen-treated rabbits protected from death by atropine. The evidence is consistent with the adrenergic nature of the final stimulus in pituitary activation and is strong indication that atropine blocks the copulation stimulus by some means other than its capacity to counteract adrenergic effects.