Serial Transrectal Ultrasonography for Monitoring the Reproductive Activity of the Asiatic Black Bear (Ursus thibetanus ussuricus)

This study evaluated the structural changes in the reproductive tract of Asiatic black bears using serial transrectal ultrasonography. In addition, the ultrasonographic observations were compared with the results of vaginal cytology and hormonal analyses. The collection of blood for hormonal analysis, vaginal cytology and transrectal ultrasonography was performed in two bears (Bears 1 and 2) from June 2011 to August 2013 without mating and in a third bear (Bear 3) from April to December 2012, allowing natural mating. Serial ultrasonographic observations showed cyclic changes in ovarian structures (e.g. emergence of small follicles, growth and ovulation of dominant follicles and corpus luteum (CL) formation) during the reproductive cycles of the three bears. The diameter of the uterine horns remained similar throughout the reproductive cycle in Bears 1 and 2, and it remained similar from April until October, but an enlargement containing foetuses was observed in Bear 3 in December. The ultrasonographic observations were consistent with the data obtained through vaginal cytology and progesterone analysis during the reproductive cycle. An average of 4.0 (±0.4) dominant follicles was observed during the oestrous stage (May‐August), during which the superficial cells accounted for >90% of the total vaginal cells. In addition, the detection of an average of 2.6 (±0.2) CL was associated with increased plasma progesterone concentrations (3.0 ± 0.4 ng/ml) between June and December (near hibernation). In conclusion, serial transrectal ultrasonography demonstrated yearly oestrous (ovulation) cycles via follicular dynamics and CL formation on ovaries, accordingly with vaginal cytology and hormonal level in the Asiatic black bear.     

Chimeric alpha 2-,beta 2-adrenergic receptors: delineation of domains involved in effector coupling and ligand binding specificity

The alpha 2 and beta 2 adrenergic receptors, both of which are activated by epinephrine, but which can be differentiated by selective drugs, have opposite effects (inhibitory and stimulatory) on the adenylyl cyclase system. The two receptors are homologous with each other, rhodopsin, and other receptors coupled to guanine nucleotide regulatory proteins and they contain seven hydrophobic domains, which may represent transmembrane spanning segments. The function of specific structural domains of these receptors was determined after construction and expression of a series of chimeric alpha 2-,beta 2-adrenergic receptor genes. The specificity for coupling to the stimulatory guanine nucleotide regulatory protein lies within a region extending from the amino terminus of the fifth hydrophobic domain to the carboxyl terminus of the sixth. Major determinants of alpha 2- and beta 2-adrenergic receptor agonist and antagonist ligand binding specificity are contained within the seventh membrane spanning domain. Chimeric receptors should prove useful for elucidating the structural basis of receptor function.     

GPCR engineering yields high-resolution structural insights into beta2-adrenergic receptor function

The beta2-adrenergic receptor (beta2AR) is a well-studied prototype for heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) that respond to diffusible hormones and neurotransmitters. To overcome the structural flexibility of the beta2AR and to facilitate its crystallization, we engineered a beta2AR fusion protein in which T4 lysozyme (T4L) replaces most of the third intracellular loop of the GPCR ("beta2AR-T4L") and showed that this protein retains near-native pharmacologic properties. Analysis of adrenergic receptor ligand-binding mutants within the context of the reported high-resolution structure of beta2AR-T4L provides insights into inverse-agonist binding and the structural changes required to accommodate catecholamine agonists. Amino acids known to regulate receptor function are linked through packing interactions and a network of hydrogen bonds, suggesting a conformational pathway from the ligand-binding pocket to regions that interact with G proteins.     

Comparative Aspects of the Endotoxin- and Cytokine-Induced Endocrine Cascade Influencing Neuroendocrine Control of Growth and Reproduction in Farm Animals

Disease in animals is a well-known inhibitor of growth and reproduction. Earlier studies were initiated to determine the effects of endotoxin on pituitary hormone secretion. These studies found that in sheep, growth hormone (GH) concentration was elevated, whereas insulin-like growth factor-I (IGF-I) was inhibited, as was luteinizing hormone (LH). Examination of the site of action of endotoxin in sheep determined that somatotropes expressed the endotoxin receptor (CD14) and that both endotoxin and interleukin-Iβ activated GH secretion directly from the pituitary. In the face of elevated GH, there is a reduction of IGF-I in all species examined. As GH cannot activate IGF-I release during disease, there appears to be a downregulation of GH signalling at the liver, perhaps related to altered nitration of Janus kinase (JAK). In contrast to GH downregulation, LH release is inhibited at the level of the hypothalamus. New insights have been gained in determining the mechanisms by which disease perturbs growth and reproduction, particularly with regard to nitration of critical control pathways, with this perhaps serving as a novel mechanism central to lipopolysaccharide suppression of all signalling pathways. This pathway-based analysis is critical to the developing novel strategies to reverse the detrimental effect of disease on animal production.     

Relationship between endometritis and oxidative stress in the follicular fluid and luteal function in the buffalo

In this study, alteration in the follicular fluid composition and luteal function was investigated in the buffalo with endometritis. Genitalia were classified into cytological and purulent endometritis on the basis of polymorphonuclear cell cut off while non‐endometritis served as control (n = 10/group). In the follicular phase, the number of surface follicles was counted, diameter of the largest follicle was measured and the follicular fluid was assayed for total protein, cholesterol, malondialdehyde (MDA), total antioxidant capacity (TAC), oestradiol (E₂) and progesterone (P₄). The P₄ content of corpus luteum during mid‐luteal phase was estimated by radioimmunoassay. Ovaries from the follicular phase of oestrous cycle showed no significant difference in the total number of surface follicles, size of the largest follicle and volume of follicular fluid in the buffaloes with and without endometritis (p > .05). However, the antral fluid of the largest follicle from the genitalia of buffalo with cytological and purulent endometritis showed a significant decrease in the concentration of total protein, cholesterol, TAC and E₂ and a significant increase in the concentration of MDA and P₄ (p < .05). The results indicated that there is an association between endometritis and decreased ovarian function.     

Efficacy of Ovsynch Protocol with Antiprolactin Treatment for Timed Artificial Insemination During Non‐breeding Seasons in Yaks (Poephagus grunniens L.)

An attempt was undertaken to investigate the efficacy of Ovsynch protocol for timed artificial insemination (TAI) with or without Norprolac (antiprolactin) treatment during non‐breeding season (winter months) in yaks (n = 25). During non‐breeding season, plasma prolactin profile has been reported high due to cold and nutritional stress. The Norprolac dose of i.m. administration was standardized for prolactin suppression. Three different doses viz. 2.5, 5.0 and 7.5 mg were attempted and the dose of 7.5 mg Norprolac i.m. per animal was found to be suitable for suppression of prolactin levels up to 30 h. Ovsynch treatment with Norprolac induced more number of oestrous symptoms per animal (4.8 vs 2.1), higher LH peak concentration (24.01 vs 16.16 ng/ml), longer duration of LH surge (6.8 vs 5.2 h) and higher conception rate (70 vs 30%) in Ovsynch plus Norprolac treated animals compared with animals treated with Ovsynch alone. Therefore, this study clearly indicates the opportunity for practical application of the Ovsynch plus Norprolac protocol for TAI in yaks during non‐breeding seasons.     

Plasma Concentrations of 13, 14‐Dihydro‐15‐keto‐Prostaglandin F2α, Progesterone and Cortisol During Periparturient Period in Yaks (Poephagus grunniens L.)

An attempt was made to determine plasma concentrations of, 13, 14‐dihydro‐15‐keto‐prostaglandin F_2α (PGFM), cortisol and progesterone during periparturient period in yak. Plasma PGFM level showed an increasing trend beginning day 5 prior to parturition (0.48 ± 0.14 ng/ml) and increased steeply thereafter to reach a peak level (17.16 ± 1.31 ng/ml) on the day of parturition. The levels, then, declined sharply on day 1 postpartum to reach 1.20 ± 0.40 ng/ml and thereafter declined gradually over the days to reach 0.28 ± 0.09 ng/ml on day 20 postpartum and this level was maintained with fluctuation within narrow limits thereafter till conclusion of the blood sampling on day 90 post‐calving. The plasma progesterone concentration on days 7 and 6 before parturition was high (2.10 ± 0.10 and 2.12 ± 0.10 ng/ml, respectively). The level then decreased gradually and abrupt fall was observed 1–2 days before parturition and became basal on day of parturition (0.24 ± 0.04 ng/ml). This basal level was maintained till the end of the blood sampling on day 90 postpartum. Plasma cortisol level showed an increasing trend beginning day 2 prior to parturition (2.36 ± 0.65 ng/ml) and increased steeply thereafter to reach a peak level (26.65 ± 5.28 ng/ml) on the day of parturition. The levels, then, declined gradually over the days and touched 2.36 ± 0.25 ng/ml on day 3 postpartum and this level was maintained with fluctuation within narrow limits thereafter till day 7 post‐calving.     

betaAR signaling required for diet-induced thermogenesis and obesity resistance

Excessive caloric intake is thought to be sensed by the brain, which then activates thermogenesis as a means of preventing obesity. The sympathetic nervous system, through beta-adrenergic receptor (betaAR) action on target tissues, is likely the efferent arm of this homeostatic mechanism. To test this hypothesis, we created mice that lack the three known betaARs (beta-less mice). beta-less mice on a Chow diet had a reduced metabolic rate and were slightly obese. On a high-fat diet, beta-less mice, in contrast to wild-type mice, developed massive obesity that was due entirely to a failure of diet-induced thermogenesis. These findings establish that betaARs are necessary for diet-induced thermogenesis and that this efferent pathway plays a critical role in the body's defense against diet-induced obesity.