Abstract
Background:
Cutaneous mechanoreceptors detect physical stimuli. Their pathways to the central nervous system are not fully mapped. Understanding these connections helps explain sensory regulation of endocrine function.

Aim:
This study mapped the anatomical connections from plantar skin mechanoreceptors to hypothalamic nuclei. It examined structural, cellular, and neurochemical features.

Methods:
Twenty-four male Wistar rats were used. Plantar skin was stimulated with calibrated vibration. Tissue samples from skin, spinal cord, and hypothalamus were collected. Tract tracing used Fast Blue and BDA tracers. Immunofluorescence labeled c-Fos, CRH, CGRP, and Substance P. Confocal microscopy visualized pathways. Hormonal assays measured ACTH and corticosterone levels. ChIP-qPCR assessed histone modifications. Gene expression of CRH, Fos, AVP, NR3C1, and BDNF was measured by RT-qPCR. HPLC identified neuropeptide concentrations.

Results:
Tracer analysis revealed direct afferent projections from plantar skin to the hypothalamic paraventricular nucleus. Immunofluorescence showed strong c-Fos and CRH expression in stimulated animals. Serum ACTH and corticosterone levels increased after stimulation. Histone acetylation (H3K27ac) was elevated in hypothalamic neurons. RT-qPCR showed increased CRH, Fos, AVP, NR3C1, and BDNF expression. HPLC confirmed elevated CRH, Substance P, NPY, and β-Endorphin levels after stimulation.

Conclusion:
The plantar skin mechanoreceptors connect directly to hypothalamic regions. Mechanical stimulation activates neuroendocrine responses. This pathway integrates cutaneous sensation with hormonal regulation.

Key words: ACTH; Anatomy; Corticosterone; Hypothalamus; Mechanoreceptors.