Up-regulation of oxytocin receptor gene and protein in the sheep anterior pituitary by a dopamine derivative (salsolinol)

Abstract

Górski K., Hasiec M., Zielińska-Górska M., Fülöp F., Misztal T. Specific oxytocin receptors (OTR) have been identified in the anterior pituitary (AP), and their expression has been shown to change in relation to the animal physiological stage, whereas salsolinol (a derivative of dopamine) has been shown to stimulate the synthesis and release of oxytocin (OT) in lactating sheep. In the present study, the expression of both OTR mRNA and OTR protein in the AP were examined by real-time quantitative PCR and enzyme-linked immunosorbent assay, either in anestrous or lactating sheep 48 h after weaning lambs. Moreover, the effect of salsolinol administered via an intracerebroventricular (i.c.v.) infusion was tested in additional sheep at the same physiological stages. The i.c.v. infusions of Ringer-Locke (control) and salsolinol solutions were carried out from 10:00 to 15:00 h in a serial manner, i.e. five 30-min infusions at 30-min intervals. We observed both OTR gene and OTR protein expression in the AP, in both anestrous and lactating sheep, but it was significantly (P < 0.01 and P < 0.05, respectively) higher in the AP of lactating animals compared to anestrous animals. Salsolinol i.c.v. treatment in anestrous sheep evoked a significant (P < 0.05) increase in both OTR gene and OTR protein expression compared to control animals. In contrast, salsolinol did not affect either OTR gene or OTR protein expression in lactating sheep. In conclusion, the expression of OTR in the sheep AP is upregulated by salsolinol. The effect of salsolinol was more pronounced in non-lactating sheep, with a reduced response due to ongoing OTR expression in lactating animals. Increased expression of OTR in the AP of lactating sheep may be related to the stimulation of pituitary lactotrophs by OT following the release of prolactin during suckling.

Reproductive Physiology and Advanced Technologies in Sheep Reproduction

“…Moreover, oxytocin regulates numerous functions, including follicle luteinization, steroidogenesis, and hormonal regulation of estrous cycles [49]. Oxytocin action is mediated by a G protein-coupled receptor that is known as the oxytocin receptor (OTR) [50]. As the OTR is activated by oxytocin, several second messengers are released, including intracellular Ca 2+ , which activates MAP-kinase pathways, facilitates smooth muscle contractions, and increases protein synthesis.…”

Undernutrition-induced substance metabolism and energy production disorders affected the structure and function of the pituitary gland in a pregnant sheep model

“…It receives signals from the brain and secretes a variety of hormones such as the growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, luteinizing hormone, follicular stimulating hormone, and prolactin, etc. ( 2 ). These hormones released from the pituitary gland participate in physiological activities such as metabolism, growth and development, reproduction, and lactation ( 3 ).…”

The Ethyl Acetate Fraction of Torbangun (Coleus amboinicus L.) Leaves Increasing Milk Production With Up-Regulated Genes Expression of Prolactin Receptor

“…Estradiol receptors (ER) play a role in the regulation of tryptophan hydroxylase enzymes, where it is known that tryptophan is a neurotransmitter precursor of serotonin [15,16]. Moreover, the other plausible mechanisms involved in increasing milk production can be by up-regulation of oxytocin receptor gene and protein in the anterior pituitary [17].…”