Leptin and ghrelin concentration in hyperthyroid cats before and after radioactive iodine therapy compared to euthyroid control cats

Measurement of Ghrelin as a Marker of Appetite Dysregulation in Cats with and without Chronic Kidney Disease

Appetite abnormalities and weight loss are important comorbidities in the treatment of chronic kidney disease (CKD) in cats. Ghrelin, a key hormone involved in the regulation of appetite and metabolism, is a potential marker of appetite dysregulation in cats with CKD. The aim of this study was to compare the plasma concentrations of acylated, desacyl, and total ghrelin in normal cats and cats with CKD. Storage methodology was investigated prior to evaluating ghrelin concentrations in normal and CKD cats to facilitate clinical sample collection. Twelve normal cats and twelve cats with CKD were enrolled. Plasma acylated and total ghrelin concentrations were measured using radioimmunoassay. Desacyl ghrelin was calculated (total ghrelin minus acylated ghrelin). Cats with CKD had significantly increased total ghrelin and calculated desacyl ghrelin concentrations in comparison to normal cats (p < 0.0001 and p = 0.0001). There was no significant difference in active ghrelin concentrations between groups. Both total ghrelin and calculated desacyl ghrelin were significantly correlated with serum creatinine concentrations (p < 0.0001, r = 0.70 and p < 0.0001, r = 0.73). Elevated plasma desacyl ghrelin concentrations in cats with CKD provides evidence for dysregulation of appetite in feline CKD.

Interrelationships between metabolic hormones, leptin and ghrelin, and oil-related contaminants in control of oxytocin and prostaglandin F release by feline ovaries

We examined the effects of metabolic hormones leptin and ghrelin, and the oil-related environmental contaminants toluene and xylene on the release of ovarian hormones by gravid and non-gravid cats, as well as the functional interrelationships between metabolic hormones and contaminants. Ovarian fragments of non-gravid cats were cultured with and without leptin and toluene. Next, ovarian fragments of either non-gravid or gravid animals were cultured with and without ghrelin and xylene. Oxytocin (OT) and prostaglandin F (PGF) release was measured using ELISA. We confirm ovarian OT and PGF production by feline ovary, demonstrate the involvement of leptin and ghrelin in controlling OT and PGF release, show the direct influence of toluene and xylene on feline ovarian secretory activity, indicate the ability of leptin and ghrelin to mimic and promote the main contaminant effects, demonstrate that oil-related contaminants can prevent and even invert the effects of leptin and ghrelin on the ovary, and suggest the gravidity-associated changes in ability of ghrelin to promote xylene action on PGF (but not to OT), but not in basic ovarian OT and PGF release and their response to ghrelin or xylene.