Prolactin and growth hormone responses to dermorphin in patients with prolactin-secreting pituitary adenoma

Dermorphin-induced hyperexcitability in hippocampal CA3 and CA1 in vitro

Dermorphin, a specific mu 1-opioid receptor agonist, has been studied for its effects on the physiology of the rat hippocampal slice. Population responses in CA3 to threshold levels of stimulation from both the Schaffer collaterals and mossy fibers were markedly enhanced in the presence of 50-100 nM dermorphin, while CA1 responses to threshold Schaffer collateral stimulation were less effected. Responses at higher stimulus levels than threshold were negligibly responsive to dermorphin, although at 500 nM dermorphin all responses became epileptiform and in some slices spontaneous bursting erupted. [L-Ala2]Dermorphin, a biologically inactive dermorphin analogue, did not increase response amplitudes nor evoke epilepsy in the slice. 5 microM naloxone blocked the effect of dermorphin on Schaffer collateral and mossy fiber-evoked responses, though less effectively in the latter case. These data provide in vitro evidence to support in vivo observations that excessive mu-opioid receptor activation can be proconvulsant in the hippocampus, but that normally the receptors may function as facilitatory modulators of responses in the threshold range.

Drug-induced changes in prolactin secretion. Clinical implications

Prolactin secretion is affected by various diseases as well as by many drugs in humans and animals. While marked hyperprolactinaemia suggests the presence of a pituitary tumor, moderate changes may also occur in various endocrine or non-endocrine disorders. Drugs can interfere with prolactin regulation via complex mechanisms at the hypothalamus or at the pituitary site, but possible changes in prolactin metabolism are poorly understood as yet. This survey of the literature up to June 1986 covers the influence of various groups of drugs and agents on the plasma prolactin level under various conditions. It contains information that will facilitate evaluation of whether hyper- or hypoprolactinaemia may result from therapeutic intervention or must be related to an underlying disease. It is obvious that more subtle changes can be revealed by the use of dynamic tests either to stimulate or to suppress prolactin secretion.