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The pituitary gland is a key endocrine gland in all classes of vertebrates, including mammals. The pituitary gland is an important component of hypothalamus–pituitary–target organ hormonal regulatory axes and forms a functional link between the nervous system and the endocrine system. In response to hypothalamic stimuli, the pituitary gland secretes a number of hormones involved in the regulation of metabolism, stress reactions and environmental adaptation, growth and development, as well as reproductive processes and lactation. In turn, hormones secreted by target organs at the lowest levels of the hormonal regulatory axes regulate the functions of the pituitary gland in the process of hormonal feedback. The pituitary also responds to other peripheral signals, including adipose-tissue-derived factors. These substances are a broad group of peptides known as adipocytokines or adipokines that act as endocrine hormones mainly involved in energy homeostasis. Adipokines, including adiponectin, resistin, apelin, chemerin, visfatin, and irisin, are also expressed in the pituitary gland, and they influence the secretory functions of this gland. This review is an overview of the existing knowledge of the relationship between chosen adipose-derived factors and endocrine functions of the pituitary gland, with an emphasis on the pituitary control of reproductive processes.

Visfatin (VIS), also known as nicotinamide phosphoribosyltransferase (NAMPT), is the rate-limiting enzyme in the biosynthesis of nicotinamide adenine dinucleotide (NAD+). Recently, VIS has been also recognized as an adipokine. Our previous study revealed that VIS is produced in the anterior and posterior lobes of the porcine pituitary. Moreover, the expression and secretion of VIS are dependent on the phase of the estrous cycle and/or the stage of early pregnancy. Based on this, we hypothesized that VIS may regulate porcine pituitary function. This study was conducted on anterior pituitary (AP) glands harvested from pigs during specific phases of the estrous cycle. We have shown the modulatory effect of VIS in vitro on LH and FSH secretion by porcine AP cells (determined by ELISA). VIS was also found to stimulate cell proliferation (determined by Alamar Blue) without affecting apoptosis in these cells (determined using flow cytometry technique). Moreover, it was indicated that VIS may act in porcine AP cells through the INSR, AKT/PI3K, MAPK/ERK1/2, and AMPK signaling pathways (determined by ELISA or Western Blot). This observation was further supported by the finding that simultaneous treatment of cells with VIS and inhibitors of these pathways abolished the observed VIS impact on LH and FSH secretion (determined by ELISA). In addition, our research indicated that VIS affected the mentioned processes in a manner that was dependent on the dose of VIS and/or the phase of the estrous cycle. Thus, these findings suggest that VIS may regulate the functioning of the porcine pituitary gland during the estrous cycle.

The species which make up the avian community are governed by a multitude of environmental and internal influences, and the crucial role of community ecology is to discern and explain the patterns arising from these influences. Some such influences are habitat structure and seasonality. This study aimed to investigate the structure of the avian community and population densities of birds in relation to habitat changes made by man, and in relation to differential rainfall. The study was set up in an urbanized riparian forest on the Zambezi River, NE Namibia. The forest close to the river bank has been slightly altered by human activities, while the one laying further afield has been highly modified by human settlements. The avian community was quantified using the mapping method. Counts were conducted in two wet seasons in 2013/14 and 2015/16. The rainfall was higher in the 2013/14 (428 mm) than the 2014/15 (262 mm) rainy season. In both seasons, 113 bird species were recorded. However, in particular, 91 species were recorded in 2013/14 and 101 in 2015/16. The Sorensen Index of Similarity between those two seasons was I = 0.89. Also, the proportion of dominant species was similar in both seasons, and the group was composed of the Dark-capped Bulbul, Red-eyed Dove, Laughing Dove, Blue Waxbill, and Grey-headed Sparrow. The Community Dominance was identical in both seasons when compared. Also, the diversity indices were very similar in both seasons. Also, all three diversity indices were almost identical in both seasons. The overall density was only slightly higher in 2015/16 than in 2013/14. The proportions of particular nesting, feeding, habitat, and residency guilds were very similar in both seasons when compared. The overall density was slightly higher in 2015/16 than in 2013/14, but the difference was not statistically significant. Also, for any particular bird species, the differences in population density between the two seasons were not statistically significant. Several bird species showed, however, statistically significant differences in their population densities between the natural and transformed portions of the riparian forest. The avian assemblage is probably stable over the years in regard to the number of breeding species and their densities, irrespective of year-to-year differences in rainfall, as water is not a limiting factor in this habitat. Bird species classified as forest specialists appear to be negatively affected by habitat transformation, while generalists (ecotone species) probably benefit from this transformation.