Pulsatile cerebrospinal fluid and plasma ghrelin in relation to growth hormone secretion and food intake in the sheep.

As in other species, exogenous administration of ghrelin, an endogenous ligand for the growth hormone (GH) secretagogue receptors can stimulates feeding behaviour and GH secretion in the sheep. However, the importance of endogenous ghrelin for these two functions as well as its central or peripheral origin remained to be established. In the present study, cerebrospinal fluid (CSF) ghrelin concentrations were measured in five anoestrous ewes and found to be more than 1000-fold lower than circulating plasma levels, in keeping with the even lower concentration in hypothalamic compared to abomasum tissue extracts.

Effects of age on thermoregulatory responses during cold exposure in a nonhuman primate, Microcebus murinus.

Cold resistance appears altered with aging. Among existing hypotheses, the impaired capacity in response to cold could be related to an altered regulation of plasma IGF-1 concentration. The combined effects of age and cold exposure were studied in a short-living primate, the gray mouse lemur (Microcebus murinus), which adjusts its energy balance using a daily torpor phase, to avoid high energy cost of normothermia maintenance.

Obestatin partially affects ghrelin stimulation of food intake and growth hormone secretion in rodents.

Administration of ghrelin, an endogenous ligand for the GH secretagogue receptor 1a (GHSR 1a), induces potent stimulating effects on GH secretion and food intake. However, more than 7 yr after its discovery, the role of endogenous ghrelin remains elusive. Recently, a second peptide, obestatin, also generated from proteolytic cleavage of preproghrelin has been identified.

Cellular localization of apelin and its receptor in the anterior pituitary: evidence for a direct stimulatory action of apelin on ACTH release.

Apelin is a bioactive peptide recently identified as the endogenous ligand of the human orphan G protein-coupled receptor APJ. The presence of apelin-immunoreactive nerve fibers, together with the detection of apelin receptor mRNA in the parvocellular part of the paraventricular nucleus and the stimulatory action of apelin on corticotropin-releasing hormone release, indicate that apelin modulates adrenocorticotropin (ACTH) release via an indirect action on the hypothalamus. However, a direct action of apelin in the anterior pituitary cannot be excluded.

Pituitary cocaine- and amphetamine-regulated transcript expression depends on the strain, sex and oestrous cycle in the rat.

Cocaine- and amphetamine-regulated transcript (CART) mRNA and peptides are abundant in the adenohypophysis, but their role in pituitary function has not yet been elucidated. CART peptides were recently shown to colocalise with luteinising hormone (LH) or prolactin in rat anterior pituitary, and contradictory results concerning the peptide effects on pituitary hormonal secretions were obtained in vitro from pituitary cell cultures. Thus, we reinvestigated the expression of CART mRNA within the pituitary.