Identification of neuropeptides in the HNS and analysis of neuropeptide profiles in extracts from individual camels using mass spectrometry indicates that overall AVP peptide levels decreased in the HNS during summer compared to winter, perhaps due to increased release during periods of dehydration in the dry season.
In the current review, we summarize the literature on the relationship between elevated osmolarity, AVP, copeptin, and dehydration with renal and cardiovascular outcomes and underlying classical and novel pathophysiologic pathways.
It was hypothesised that plasma copeptin would rise with dehydration from occupational heat stress, concurrent with sympathoadrenal activation and reduced glomerular filtration, and that these changes would reflect T <sub>c</sub> responses.
However, the effects of these receptors on AVP release were masked by complex stimuli such as overnight dehydration and DOCA-salt treatment, which simultaneously induce osmotic, volemic, and pressor stresses.
Osmosensory neurons are specialized cells activated by increases in blood osmolality to trigger thirst, secretion of the antidiuretic hormone vasopressin, and elevated sympathetic tone during dehydration.
Despite polyuria, which could potentially induce dehydration, AVP mRNA expression was decreased in the supraoptic nucleus, and the AVP mRNA poly(A) tail length was shortened in FNDI mice compared with wild-type mice.
Affected adults became dehydrated; their median plasma AVP level was less than 1.0 pmol/liter, but their median fasting plasma ACTH was 2-fold greater than the level of nonaffected adults (10.0 vs. 5.0 pmol/liter; P = 0.008).
Our results in the methadone group suggest (a) near-maximal stimulation of prolactin secretion, with a blunted prolactin response to insulin hypoglycemia, (b) mild suppression of cortisol levels, but an exaggerated cortisol response to stimulation, (c) a delayed and inhibited insulin response to food ingestion with resulting mild hyperglycemia, (d) low body weight, but elevated calorie ingestion, and (e) inability to concentrate urine when dehydrated, which was partially corrected by administration of arginine vasopressin.