Efecto del ciclo lunar en algunas características morfológicas y funcionales del ovario en cobayas (Cavia porcellus)

Abstract

This study aimed to assess the influence of the lunar cycle (LC) on serum progesterone and estradiol concentrations, and follicular count in guinea pigs. Eighty nulliparous guinea pigs, aged 3-3.5 months and weighing 106190 g were randomly assigned to four time points (n=20 each; 5 animals per phase for 4 consecutive LCs) of the LC: new moon (NM); crescent quarter (CQ); full moon (FM); waning quarter (WQ). Animals were fasted for 12 hours and anesthetized with sevoflurane. In an unconscious state, blood samples were taken by cardiac puncture and the animals were immediately euthanized by cervical dislocation. Ovaries were removed and weighed, and one of them was histologically processed. Different categories of follicles in the whole ovary were counted by duplicate (two slices separated by 250 μm) under a stereoscope. Progesterone (P4) and estradiol (E2) concentrations were quantified by chemiluminescence. Data were analyzed by the general lineal model and the last square means test of SAS. Ovarian weight and gonadosomatic index were not influenced by moon phase. LC influenced serum P4 (P=0.0489) and E2 (P<0.0001) concentrations. Progesterone was greater (P<0.05) in NM (5  0.7 ng/ml) than in FM (2.6  0.7 ng/ml) and WQ (3.1  0.7 ng/ml). Estradiol was greater (P<0.0001) in NM (86.8  3 pg/ml) than in CQ (71.7  2.9 pg/ml), FM (77.1  2.9 pg/ml) and WQ (70.3  3 pg/ml). LC affected the number (P=0.0005) and percentage (P=0.0014) of large antral follicles (LAF). Number of LAF was greater in NM (3.0  0.49) than in CQ (2.0  0.48; P>0.05), FM (0.6  0.46) and WQ (0.8  0.49) (P<0.01). The number (P=0.0019) and percentage (P=0.0013) of primordial follicles (PF) were influenced by moon phase, with lower values in the number of PF in WQ (13.3  1.7) than in NM (18.8  1.6), CQ (20.3  1.6) and FM (22.5  1.5) (P<0.01). The number of corpora lutea and other follicular categories were similar among lunar phases. In conclusion, LC influenced circulating concentrations of ovarian steroids and the proportions of large and primordial antral follicles in guinea pigs.