• brain
• hypoparathyroidism
• rat

Hypoparathyroidism (HypoPT) is a rare endocrine disease which is characterized by hypocalcaemia and undetectable or inappropriately low serum parathyroid hormone (PTH), leading to hypocalcaemia, hypercalciuria, hyperphosphatemia and abnormal skeletal mineralization. Post-surgical HypoPT (PS-HypoPT) is the most common cause of HypoPT and is caused by accidental parathyroid removal/injury during neck surgery. Patients suffering from this condition complain of a number of complications. From a neuropsychological standpoint, patients with HypoPT present cognitive and affective symptoms: the more plausible pathophysiological mechanism resides in a direct effect of PTH in the central nervous system (CNS), but these mechanisms are still not completely elucidated.
The aim of this study was to evaluate the effects of PTH deprivation on CNS in an animal model (rat) of post-surgical hypoparathyroidism, by a cognitive/behavioural assessment approach.
The whole animal group included 30 animals divided into two groups: the first group consisting of 15 healthy rats (WT) as control group and the second group consisting of 15 rats with post-surgical hypoparathyroidism (PTx), obtained by the surgical removal of parathyroids and treated with gluconate calcium 1% in the water to maintain normocalcemia.
Serum calcium levels and 25OHD levels did not significantly differ between the two group.
The Morris Water Maze was used to assess spatial learning and memory. This test was performed for each animal in seven consecutive days and the escape latency parameter was used to assess the performance during training and final probe test. PTx animals displayed a statistically significant worse performance (higher escape latency) compared to WT in the first days, which was improved during the training and did not statistically differ from WT at the probe test.
The Elevated Plus Maze test was used to assess anxiety-related behaviour. PTx and WT did not show statistically significant differences in the performance at this test.
This study highlights and confirms the importance of PTH at the level of the Central Nervous System and suggests that PTH could play a role in spatial learning and short-term memory. Further studies are warranted to clarify the molecular mechanisms of PTH effects in brain.