Influence of Melatonin on Maturation of Male Germ Cells.

We studied the influence of epiphysectomy and administration of melatonin to epiphysectomized outbred white rats on the level and daily dynamics of damage to the genetic material of developing male germ cells. Epiphysectomy leads to an increase in the level of damage in the DNA structure and the disappearance of the circadian rhythm of the activity of repair enzyme PARP-1 and the apoptosis-inducing enzyme caspase-3. The administration of melatonin to animals after epiphysectomy reduces the level of DNA damage, restores the circadian rhythm of activity of PARP-1 and caspase-3. These fundings suggest that melatonin can indirectly protect DNA of maturing male gametes.

Phase Analysis of Ultradian Rhythms of Body Temperature in Laboratory Mice Maintained under Constant Illumination at Different Longitudinal Locations.

The study examined the rhythmic oscillations of body temperature with the period ranging 100-400 min in three groups of laboratory mice maintained under persistent artificial illumination in Moscow and Ulyanovsk. The difference in the moments of sunrise or sunset in these towns is about 1 h. The greatest rhythmic oscillations of body temperature in examined mice had the periods of 100-400 min. The phase analysis of 100-200-min rhythms revealed their synchronicity with local but not universal time despite the mice had no photic signs indicating alternation of day and night. Of them, the most pronounced were the rhythms with the periods of 121, 143, 151, and 186 min. The present data suggest existence of an external environmental synchronizer of body temperature ultradian rhythms related to local solar time.

Characteristics of 4-Day Infradian Biorhythms in Mature Male Wistar Rats after Pinealectomy.

We studied the effect of pinealectomy on the parameters of 4-day infradian biorhythms in mature male Wistar rats. It was shown that pinealectomy did not change the period and phase of infradian biorhythm of total locomotor activity, serum concentrations corticosterone and testosterone, and mitotic index of esophageal epithelium. No significant changes in the number of nucleated cells in the spleen of pinealectomized animals in comparison with intact animals were found. The amplitude of biorhythms of locomotor activity and corticosterone and testosterone concentrations did not significantly change in pinealectomized animals. Despite the important role of the epiphysis in the regulation of circadian biorhythms in mammals, this organ is not the main synchronizer of infradian biorhythms of glucocorticoid and sex hormones in male Wistar rats.

Effect of the Peptide Calcium Channel Blocker ω-hexatoxin-Hv1a on Cell Death during Ischemia/Reperfusion in vitro.

Apoptosis and necrosis during reperfusion after ischemia are key mechanisms at the cellular level leading to damage. The development of pathological conditions is preceded by intracellular calcium ion overload both at the stage of ischemia and at the stage of reperfusion. In this regard, one of the strategies aimed at reducing damage during ischemia/reperfusion is associated with the use of calcium channel blockers. The aim of the study was to study the effect of a peptide toxin, a calcium channel blocker ω-hexatoxin-Hv1a, on different types of epithelial cell death during in vitro reconstruction of ischemia/reperfusion conditions characteristic of organ transplantation. Materials and Methods: In this study, we used CHO-K1 epithelial cell culture. Changes in apoptosis, necrosis, cell index, and calcium ion concentration were assessed when modeling ischemia/reperfusion processes in vitro with the addition of a calcium channel blocker toxin. Ischemic and reperfusion injury was achieved by oxygen and nutrient deprivation followed by reperfusion in a complete nutrient medium. The measurements were performed using a multimodal plate reader-fluorimeter. Results: An increase in apoptosis, necrosis, and the concentration of calcium ions was recorded when modeling ischemia/reperfusion processes. A decrease in the level of apoptosis and necrosis, as well as the concentration of calcium ions to a physiological level or a level close to physiological, was noted when the toxin was added at a concentration of 50 nM at the reperfusion stage. The cell index showed a faster restoration in the presence of the toxin. Conclusion: The experimental data confirm the hypothesis of a beneficial effect of peptide calcium channel blockers on the state of epithelial cells during reperfusion after ischemia and can be considered for further study as a strategy for organ adaptation before reperfusion.

A method for extirpation of the pineal gland in albino rats.

A method for extirpation of the pineal gland in albino rats and other rodents (e. g., ground squirrels) is proposed. Epiphysectomy is carried out by resection of a fragment of the bone with the underlying pineal gland. Using this method, many animals can be operated within a short period; the method is reliable and simple, which recommends it for chronobiological studies.

Effect of epiphysectomy on the circadian dynamics of antiradical activity of chalone-antichalone system of albino rat liver.

Antiradical activity of the chalone-antichalone system in the liver of albino rats is characterized by circadian rhythms. The production of tissue regulators of proliferation is synchronized with the 24-h light/darkness cycle. Active phase of the rhythm of antiradical activity falls on night hours. Epiphysectomy caused disappearance of the circadian rhythm of activity of the liver chalone-antichalone system in albino rat.

Effects of pineal peptides on circadian dynamics of spermatogonia proliferation in albino rats.

Mitotic index of type B spermatogonia in intact animals is characterized by a circadian rhythm. Mitotic index increased and its circadian rhythm disappeared after pinealectomy. Treatment with Epithalamin for 14 days restored the circadian rhythm. The circadian biorhythm of spermatogonia proliferation suggests the presence of circadian rhythm of spermatogenesis in general and its regulation by the pineal gland.