The localization of CRF-41 related peptide was studied in the brain and posterior pituitary of the homozygous rats for the inherited diabetes insipidus (Brattleboro strain, DI) and of the Long-Evans rats (LE) as control. It was compared to the distribution of vasopressin (AVP), oxytocin (OXY) and OXY-neurophysin (N I). In both strains, CRF-41 was identified in two morphologically distinct systems:one was a hypothalamoneurohypophysial system simultaneously containing CRF-41, OXY and N I; the other was a hypothalamoinfundibular system carrying CRF-41 only. CRF containing neurons were located in the periventricular area of the anterior hypothalamus, in the retrochiasmatic part of the supraoptic nuclei (SON) and, for some of them, in the antechiasmatic part of SON. CRF immunostainings were enhanced by colchicine treatment in LE rats and by DDAVP therapy in DI rats.

We tested whether cardiac mass can be related to decreased aortic stiffness in an original rat model of isolated systolic hypertension. Increased aortic stiffness was produced by calcium overload of elastic arteries after vitamin D3 plus nicotine treatment. Half of the animals were chronically treated with the angiotensin-converting enzyme inhibitor perindopril (1 mg/kg per day PO). Rats were pithed, and lower body vascular resistance was measured. Blood pressure was then increased by phenylephrine infusion, and carotidofemoral pulse wave velocity was measured. This value together with those for thoracic aorta internal diameter and medial thickness (determined after in situ fixation and histomorphometry) were used to calculate elastic modulus. Vitamin D3 plus nicotine treatment produced parallel increases in cardiac mass and elastic modulus, with a significant correlation between the two. There was no significant change in resistance. Treatment with perindopril reversed the changes in cardiac mass and elastic modulus but had no effect on resistance after calcium overload of the elastic arteries. In this model of isolated systolic hypertension, we showed that cardiac mass is related to arterial elasticity.

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Galanin (GAL) is a neuropeptide cosynthesized with vasopressin (AVP) in neurons of the hypothalamo-neurohypophysial system. It increases food intake when injected into the brain and elicits an overconsumption of fat. The Brattleboro rat (DI) is genetically unable to produce AVP; the AVP-deficient-producing neurons of the hypothalamo-neurohypophysial system of DI rats are chronically stimulated and DI rats suffer from diabetes insipidus. We studied the central expression of GAL and the dietary preferences in the DI rat. GAL was overexpressed in the hypothalamus of the DI rat. GAL mRNA was higher by 1.8-fold in the supraoptic (P < 0.05) and by four-fold in the paraventricular nuclei (P < 0.001) of male and female DI rats compared with those of control Long Evans (LE) rats. However, GAL mRNA was lower in the arcuate nuclei of DI rats and equal to that of LE rats in the dorsomedian nuclei. We also measured a high preference for a lipid diet (45% of the daily consumption) when DI rats ate from a choice of the three macronutrients. Chronic infusion with deamino-8D-AVP (agonist of AVP V2 receptors) prevented the diabetes insipidus and the chronic stimulation of the hypothalamo-neurohypophysial system of the DI rats. However, the treatment did not suppress the overexpression of GAL, nor did it affect the rats' preference for a lipid diet. We conclude that the DI rat provides a novel animal model in which a spontaneous dietary preference correlates with the overexpression of one of the hypothalamic peptides, GAL.