Elevated Neuropeptide Y Concentrations in the Central Hypothalamus of the Spontaneously Diabetic BB/E Wistar Rat

Insulin-deficient diabetes causes hypothalamic and pituitary dysfunction. The possible role of hypothalamic regulatory peptides in mediating these disturbances was investigated in spontaneously diabetic BB/E Wistar rats. Concentrations of 10 regulatory peptides were measured in the central (nucleus-rich) and lateral parts of the hypothalamus in 18 diabetic and 5 non-diabetic BB/E rats. Diabetic rats were treated with either intensified or low-dose insulin schedules to achieve moderate or severe hyperglycaemia (mean blood glucose concentrations, 8 and 20 mmol l-1 respectively). Neuropeptide Y concentration and content in the central hypothalamus were increased by 30-40% in both moderately and severely hyperglycaemic diabetic groups (p less than 0.01). Lateral hypothalamic neuropeptide Y levels did not differ significantly between the groups. The only other peptide to show any significant difference between diabetic and control rats was calcitonin gene-related peptide, whose central hypothalamic concentrations were significantly increased in the severely hyperglycaemic animals. Alterations of hypothalamic neuropeptide Y, which has potent experimental effects on hypothalamo-pituitary function, may contribute to certain neuroendocrine disturbances in insulin-deficient diabetes.