Circadian and seasonal changes
in the expression of clock genes in the ovine pars tuberalis

Wojtulewicz, K.; Tomczyk, M.; Wójcik, M.; Bochenek, J.; Antushevich, H.; Krawczyńska, A.; Załęcki, M.; Herman, A. P.

doi:10.22358/jafs/169747/2023

Cited by 5 publications

(1 citation statement)

References 39 publications

(43 reference statements)

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“…Relative gene expression assays were performed by two-step RT-qPCR according to a previously published method [ 67 ]. NucleoSpin ® RNA kit (Macherey-Nagel GmbH and Co, Düren, Germany) was used to isolate the total RNA from the hypothalamic and AP samples.…”

Section: Methodsmentioning

confidence: 99%

Effect of Caffeine on the Inflammatory-Dependent Changes in the GnRH/LH Secretion in a Female Sheep Model

Herman,

Tomczyk,

Wójcik

et al. 2024

IJMS

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Caffeine is one of the most widely consumed psychoactive drugs in the world. It easily crosses the blood–brain barrier, and caffeine-interacting adenosine and ryanodine receptors are distributed in various areas of the brain, including the hypothalamus and pituitary. Caffeine intake may have an impact on reproductive and immune function. Therefore, in the present study performed on the ewe model, we decided to investigate the effect of peripheral administration of caffeine (30 mg/kg) on the secretory activity of the hypothalamic–pituitary unit which regulates the reproductive function in females during both a physiological state and an immune/inflammatory challenge induced by lipopolysaccharide (LPS; 400 ng/kg) injection. It was found that caffeine stimulated (p < 0.01) the biosynthesis of gonadotropin-releasing hormone (GnRH) in the hypothalamus of ewe under both physiological and inflammatory conditions. Caffeine also increased (p < 0.05) luteinizing hormone (LH) secretion in ewes in a physiological state; however, a single administration of caffeine failed to completely release the LH secretion from the inhibitory influence of inflammation. This could result from the decreased expression of GnRHR in the pituitary and it may also be associated with the changes in the concentration of neurotransmitters in the median eminence (ME) where GnRH neuron terminals are located. Caffeine and LPS increased (p < 0.05) dopamine in the ME which may explain the inhibition of GnRH release. Caffeine treatment also increased (p < 0.01) cortisol release, and this stimulatory effect was particularly evident in sheep under immunological stress. Our studies suggest that caffeine affects the secretory activity of the hypothalamic–pituitary unit, although its effect appears to be partially dependent on the animal’s immune status.

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Section: Methodsmentioning

confidence: 99%

Effect of Caffeine on the Inflammatory-Dependent Changes in the GnRH/LH Secretion in a Female Sheep Model

Herman,

Tomczyk,

Wójcik

et al. 2024

IJMS

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The role of QRFP43 in the secretory activity of the gonadotrophic axis in female sheep

Przybył,

Szlis,

Wysoczański

et al. 2024

Sci Rep

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In mammals reproduction is regulated by many factors, among others by the peptides belonging to the RFamide peptide family. However, the knowledge concerning on the impact of recently identified member of this family (QRFP43) on the modulation of the gonadotrophic axis activity is still not fully understood and current research results are ambiguous. In the present study we tested the in vivo effect of QRFP43 on the secretory activity of the gonadotrophic axis at the hypothalamic-pituitary level in Polish Merino sheep. The animals (n = 48) were randomly divided into three experimental groups: controls receiving an icv infusion of Ringer-Locke solution, group receiving icv infusion of QRFP43 at 10 μg per day and 50 μg per day. All sheep received four 50 min icv infusions at 30 min intervals, on each of three consecutive days. Hypothalamic and pituitaries were collected and secured for further immunohistochemical and molecular biological analysis. In addition, during the experiment a blood samples have been collected for subsequent RIA determinations. QRFP43 was found to downregulate Kiss mRNA expression in the MBH and reduce the level of IR material in ME. This resulted in a reduction of GnRH IR material in the ME. QRFP43 increased plasma FSH levels while decreasing LH levels. Our findings indicate that QRFP43 inhibits the activity of the gonadotropic axis in the ovine at the level of the hypothalamus and may represent another neuromodulator of reproductive processes in animals.

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The Effect of Endotoxin‐Induced Inflammation on the Activity of the Somatotropic Axis in Sheep

Wójcik,

Zieba,

Bochenek

et al. 2024

International Journal of Inflammation

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The hypothalamic‐pituitary‐somatotropic (HPS) axis controls many physiological and pathophysiological processes. The phenomenon of insensitivity to growth hormone resistance (GHres) was previously reported to be due to the development of inflammation. Therefore, the primary aim of the study was to determine the impact of inflammation caused by lipopolysaccharides (LPS) on the secretory activity of the HPS axis in sheep. The further goal was to determine the effect of inflammatory factors on individual components involved in intracellular signal transduction to GH via the GH receptor (GHR). The research was carried out on 24 seasonal sheep kept under a short‐day photoperiod, randomly divided into two groups. Before the experiment, the sheep estrous cycles were synchronized. The results of the current study in a sheep model showed that inflammation impairs the activity of the somatotropic axis. On the one hand, LPS injection stimulated (p < 0.01) GH secretion, and on the other hand, it reduced the liver’s sensitivity to this hormone by directly reducing (p < 0.01) GHR expression and activating the GHR inhibitory signal transduction mechanism. A symptom of such an inhibitory postreceptor signaling pathway may be due to an increase in SOCS3 expression (p < 0.01). The effect of various inhibition pathways is a significant reduction in the expression of the main transcription activator IGF1‐STAT5B (p < 0.05). The action of GHres in the liver resulted in the inhibition of IGF1 secretion, which in the long term may have negative consequences for growth and development. Our study suggests that disruption of the GH cell signaling pathway may be one of the important elements of the pathophysiology of inflammation. It can suppress growth and hepatic metabolism to spare energy expenditure.

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Circadian and seasonal changes in the expression of clock genes in the ovine pars tuberalis

Cited by 5 publications

References 39 publications

Effect of Caffeine on the Inflammatory-Dependent Changes in the GnRH/LH Secretion in a Female Sheep Model

Effect of Caffeine on the Inflammatory-Dependent Changes in the GnRH/LH Secretion in a Female Sheep Model

The role of QRFP43 in the secretory activity of the gonadotrophic axis in female sheep

The Effect of Endotoxin‐Induced Inflammation on the Activity of the Somatotropic Axis in Sheep

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