We tested the effects of thyroid hormone on Leydig cell (LC) regeneration in the adult rat testis after ethane dimethyl sulphonate (EDS) treatment. Ninety-day-old, thyroid-intact (n = 96) and thyroidectomized (n = 5) male Sprague-Dawley rats were injected intraperitoneally (single injection) with EDS (75 mg/kg) to destroy LC. Thyroid-intact, EDS-treated rats were equally divided into three groups (n = 32 per group) and treated as follows: control (saline-injected), hypothyroid (provided 0.1% propyl thiouracil in drinking water), and hyperthyroid (received daily subcutaneous injections of tri-iodothyronine, 100 microg/kg). Testing was done at Days 2, 7, 14, and 21 for thyroid-intact rats and at Day 21 for thyroidectomized rats after the EDS treatment. Leydig cells were absent in control and hyperthyroid rats at Days 2, 7, and 14; in hypothyroid rats at all ages; and in thyroidectomized rats at Day 21. The LC number per testis in hyperthyroid rats was twice as those of controls at Day 21. 3beta-Hydroxysteroid dehydrogenase (LC marker) immunocytochemistry results agreed with these findings. Mesenchymal cell number per testis was similar in the three treatment groups of thyroid-intact rats on Days 2 and 7, but it was different on Days 14 and 21. The highest number was in the hypothyroid rats, and the lowest was in the hyperthyroid rats. Serum testosterone levels could be measured in control rats only on Day 21, were undetectable in hypothyroid rats at all stages, and were detected in hyperthyroid rats on Days 14 and 21. These levels in hyperthyroid rats were twofold greater than those of controls on Day 21. Serum androstenedione levels could be measured only in the hyperthyroid rats on Day 21. Testosterone and androstenedione levels in the incubation media showed similar patterns to those in serum, but with larger values. These findings indicate that hypothyroidism inhibits LC regeneration and hyperthyroidism results in accelerated differentiation of more mesenchymal cells into LC following the EDS treatment. The observations of the EDS-treated, thyroidectomized rats confirmed that the findings in hypothyroid rats were, indeed, due to the deficiency of thyroid hormone.

Biocompatible magnetic nanoparticles hold great therapeutic potential, but conventional particles can be toxic. Here, we report the synthesis and alternating magnetic field dependent actuation of a remotely controllable, multifunctional nano-scale system and its marked biocompatibility with mammalian cells. Monodisperse, magnetic nanospheres based on thermo-sensitive polymer network poly(ethylene glycol) ethyl ether methacrylate-co-poly(ethylene glycol) methyl ether methacrylate were synthesized using free radical polymerization. Synthesized nanospheres have oscillating magnetic field induced thermo-reversible behavior; exhibiting desirable characteristics comparable to the widely used poly-N-isopropylacrylamide-based systems in shrinkage plus a broader volumetric transition range. Remote heating and model drug release were characterized for different field strengths. Nanospheres containing nanoparticles up to an iron concentration of 6 mM were readily taken up by neuron-like PC12 pheochromocytoma cells and had reduced toxicity compared to other surface modified magnetic nanocarriers. Furthermore, nanosphere exposure did not inhibit the extension of cellular processes (neurite outgrowth) even at high iron concentrations (6 mM), indicating minimal negative effects in cellular systems. Excellent intracellular uptake and enhanced biocompatibility coupled with the lack of deleterious effects on neurite outgrowth and prior Food and Drug Administration (FDA) approval of PEG-based carriers suggest increased therapeutic potential of this system for manipulating axon regeneration following nervous system injury.

The primary spermatogenic lesions following EDS administration were (i) spermiation failure and (ii) detachment of spermatids and spermatocytes associated with impairment in spermiogenesis and meiosis.

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