Structural and Functional Changes in Prolactin Endocrinocytes of the Anterior Pituitary Gland in the Process of Reparative Osteogenesis of Long Tubular Bones

The aim of the study is to investigate the numerical composition and dynamics of structural and functional changes in prolactin cells of the anterior pituitary gland during reparative regeneration of long tubular bones.

Material and methods. The study included 40 Wistar rats. A transverse fracture of the middle third of the tibial shaft was simulated in the animals of the experimental group. Cells of the fracture area and the distal part of the adenohypophysis were studied using methods of light microscopy, immunohistochemistry and morphometry on the 1st, 3rd, 7th, 14th, 21st, 28th, 44th and 61st days.

Results. The study results demonstrated that in male rats of the control group, the percentage of prolactin cells in the adenohypophysis was 7.26±0.51%. During the fracture healing of the long tubular bone in rats, there were 2 stages of stress activation of the compensatory-adaptive potencies of the prolactin endocrinocyte adenohypophysis cluster with related changes in their structures: on the 1st–3rd days (the bone fracture effect on the body with the development of post-traumatic acute inflammation) and on the 14th–21st days (peak of chondroclast lytic activity with massive chondrolysis of cartilaginous callus).

Conclusion. Thus, the importance of prolactin as a stress mediator and the need for its participation in the regulation of stress metabolic changes are evidenced. At the same time, it becomes clear that with a pronounced acute stress effect; in this study it is represented by an open fracture, even the onset of a stress response can be manifested by a maladjustment of the lactotropic activity of the adenohypophysis, which is accompanied by an early "depletion" of its structural and functional reserves and a breakdown of compensatory-adaptive potencies right on the 1st day.

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