No abstract

The hypothalamus and the pituitary gland have each been shown to play a part in the control of renal water excretion. Frank (1910) first drew attention to the evidence involving the pars nervosa in the production of diabetes insipidus. Camus & Roussy (1913) demonstrated that a lesion localized to the hypothalamus also led to the appearance of diabetes insipidus. That these apparently contradictory findings were in reality compatible has been shown by many physiological, clinical and anatomical findings. Cajal (1894) first showed that the pars nervosa was innervated by fibres arising in the hypothalamus; Greving (1923) traced these fibres to the supra-optic and paraventricular nuclei; and Kary (1924) reported retrograde degeneration in the supra-optic nuclei following injury to the pars nervosa. These findings have frequently been confirmed. The detailed and careful work of Fisher, Ingram & Ranson (1938) finally showed that the pars nervosa and the supra-optic nuclei and tracts must be considered as a single functional unit. Verney (1936) summarized his view by the statement that a normal water diuresis depends upon the integrity of the pars nervosa.Crowe, Cushing & Homans (1909) were the first to draw attention to the fact that the anterior lobe had a diuretic function. The experiments to be described in this paper were performed in order to investigate the mechanism which controls the renal excretion of water, and, in particular, the part played by the hypothalamic-pituitary system, including the anterior pituitary. Dogs were, therefore, subjected to various combinations of operations on the pituitary gland and the hypothalamus, in order to analyse, if possible, the part played by each of these structures. The operations were (1) removal of the posterior lobe alone, (2) section of the supra-optic tracts, (3) attempted removal of the anterior lobe alone, (4) simple hypophysectomy, i.e. removal of both lobes together with some of the stalk,simple hypophysectomy and section of the supra-optic tracts at the same operation, thus, it was hoped, destroying the whole pituitary system and most of the related hypothalamus and leaving only a fragment of the pars tuberalis.

Calcitonin gene-related peptide (CGRP) is a novel neuropeptide, predicted on the basis of structural analysis of the rat calcitonin gene. It is a neurotransmitter which has been suggested to take part in sensory transmission. In this study, we have examined the distribution of this peptide, α-atrial natriuretic peptide immunoreactivity (irANP) and neuropeptide Y (NPY) within different regions of the rat heart. Attempts were also made to compare the distributions of these peptides in the regions examined, through different methods of immunocytochemistry and further comparing these results with those obtained through radioimmunoassay. The distributions of the peptides in the atria were similar to results obtained with radioimmunoassay, but there were no myocytes containing irANP in the ventricles with immunocytochemistry as opposed to radioimmunoassay. While the staining obtained for irANP in the atrium was more intense in the right, CGRP and NPY nerve fibres were two to three times more abundant in the left atrium. The high local concentration of a vasoconstrictor peptide in the region of coronary vessels may suggest that it is involved in the control of vascular smooth muscle tone. The method of choice with the immunocytochemical studies was that of the susa wax technique for irANP. Caution should therefore be observed when interpreting results based only on a single staining technique.

No abstract