Faculty of Veterinary Medicine University of Zagreb
Abstract
Pregnancy is associated with a range of physiological adjustments to adapt the body to the demands of the growth of the fetus and subsequent lactation. It has been observed that agouti-related peptide (AGRP) and melanocortin-4 receptor (MC4R) are involved in energy homeostasis. A randomized controlled experimental study was planned to investigate the expression of AGRP and MC4R mRNAs in the stages of pregnancy and lactation in rat arcuate nucleus (ARC) of the hypothalamus. Thirty-two adult female rats were randomly divided into six groups. Pregnant rats were assigned into three groups (n = 6) of 7, 14, and 21 days of pregnancy. Two more groups were also assigned of non-suckling rats (n = 5), immediately separated from their pups after parturition, and suckling rats (n = 5), allowed to suckle five pups until day 8 (increasing milk). The sixth group consisted of four ovariectomized rats, which were assigned two weeks after surgery and served as control. Using real-time PCR, the relative expressions (compared to controls) of MC4R and AGRP mRNAs in ARC were calculated in the pregnant, suckling and non-suckling rats. Expression of AGRP mRNAs in pregnant rats on days 14 and 21 was higher than that observed in suckling and non-suckling rats (P<0.05). Expression of MC4R mRNAs in pregnant rats on days 14 and 21 was lower than that observed in suckling rats, and was higher on day 7 than that observed in both suckling and non-suckling rats (P<0.05). In conclusion, expression of AGRP in pregnancy and MC4R in lactation in ARC of rats controls energy homeostasis.Gravidnost je povezana s nizom fizioloških prilagodbi kojima tijelo odgovara zahtjevima povezanima s rastom fetusa i kasnije laktacije. Uočeno je da su agutiju srodan peptid (AGRP) i melanokortin-4 receptor (MC4R) uključeni u energetsku homeostazu. Randomiziranim kontroliranim pokusom planirano je u arkuatnoj jezgri (ARC) hipotalamusa štakorica istražiti ekspresiju mRNA AGRP i mRNA MC4R tijekom gravidnosti i laktacije. Trideset dvije odrasle štakorice nasumično su bile podijeljene u šest skupina. Gravidne su štakorice podijeljene u tri skupine (n = 6), s obzirom na 7., 14. i 21. dan gravidnosti. Još dvije skupine (n = 5) činile su nedojne štakorice koje su odvojene od svoje mladunčadi odmah nakon porođaja te dojne štakorice kojima je dozvoljeno dojenje 5 mladunaca do osmog dana rastuće laktacije. Četiri ovarijektomizirane štakorice, dva tjedna nakon operacije, dodijeljene su u 6. kontrolnu skupinu. Koristeći PCR u stvarnom vremenu, relativna ekspresija (usporedba s kontrolama) mRNA MC4R i mRNA AGRP u ARC izračunata je za gravidne, nedojne i dojne štakorice. Ekspresija mRNA AGRP kod gravidnih štakorica 14. i 21. dan bila je veća od one opažene kod dojnih i nedojnih štakorica (P<0,05). Ekspresija MC4R mRNA u gravidnih štakorica 14. i 21. dan bila je manja u odnosu na dojne štakorica i veća 7. dan u odnosu na skupine dojnih i nedojnih štakorica (P<0,05). Zaključno, ekspresija AGRP u ARC tijekom gravidnosti i MC4R u ARC tijekom laktacije kontrolira energetsku homeostazu štakorica
