Crop-Sac Response after Systemic and Intraventricular Administration of Neuroleptic Drugs

Abstract

Present experiments were aimed at studying in pigeons the effects of some neuroleptic agents given systemically or into the 3rd cerebral ventricle on PRL secretion and following morphological changes of the crop-sac mucosa both by classical histological methods and scanning electron microscopy. In addition, such changes were also evaluated on the basis of a semiquantitative method using a 1-4 rating scale. 3- or 5-day systemic treatment with reserpine, haloperidol and (±)-sulpiride produced an intense crop-sac response consisting of a marked epithelial hyperplasia and presence of milk-like material. Similarly, a much lower dose of haloperidol, clozapine, and the two enantiomers of sulpiride given into the 3rd cerebral ventricle for 3 consecutive days produced a marked crop-sac response. The /-sulpiride was more active in comparison to the d-enantiomer. In conclusion, present experiments show that, similarly to mammals, in pigeons neuroleptic drugs are able to stimulate prolactin secretion and suggest that these effects are mediated through an action at the hypothalamic and/or pituitary level by removing a tonic dopaminergic inhibition.

Dopaminergic inhibition of prolactin release from pituitary glands of the domestic fowl incubated in vitro

“…Harvey, Scanes, Chadwick & Bolton (19780) showed that reserpine, a central catecholamine storage depleter, increased plasma prolactin concentrations in domestic fowl. Nistico et al (1979Nistico et al ( , 1980 and Germana et al (1983) showed that systemic and central administration of dopaminergic antagonists, including haloperidol, clozapine and sulpiride, as well as reserpine, stimulated prolactin cell activity and stimulated crop sac development in pigeons. demonstrated stimulation of prolactin release in fowl injected with ot-methyl-/>ara-tyrosine, a tyrosine hydroxylase inhibitor which reduces central catecholamine stores, with the dopamine receptor blocker, pimozide and with the amine storage depletor, reserpine.…”

Neurotransmitter Effects on Release of Prolactin and Growth Hormone in Vitro From Pituitary Glands of the Pigeon, Columba Livia

“…Nistico et al (1979Nistico et al ( , 1980) administered a variety of neuroleptic drugs to pigeons and measured the crop sac response as an index of circulating prolactin levels. They found that drugs that inhibited the dopaminergic system stimulated secretion of prolactin.…”

“…Hall & Chadwick (1982) found that L-dihydroxyphenylalanine inhibited release of prolactin from fowl pituitary-hypothalamus co-incubations. Nistico, Germana, Ciriaco, Bronzetti, Rotiroti & Scapagnini (1979) and Nistico, Germana, Ciriaco & Bronzetti (1980) have shown that centrally acting drugs affect secretion of prolactin in vivo in the pigeon, as judged from ultrastructural observation of crop sac development. The effects of the monoamines, dopamine and serotonin, on release of prolactin and growth hormone from pigeon pituitary glands in vitro have now been studied.…”

Effects of synthetic mammalian thyrotrophin releasing hormone, somatostatin and dopamine on the secretion of prolactin and growth hormone from amphibian and reptilian pituitary glands incubated in vitro

“…This amine may also inhibit prolactin secretion in birds. Nistico, Germana, Ciriaco et al (1979) showed that dopamine-blocking drugs stimu¬ lated prolactin secretion in vivo in pigeons. Hall (1982) and Hall & Chadwick (1983) showed that dopamine inhibited TRH-and hypothalamus-stimulated release of prolactin in vitro from pituitary glands of the pigeon and the domestic fowl.…”