Masafumi Torii

The effects of intraventricular injection of β-endorphin on initial estrogen action to induce lordosis behavior

Ovariectomized female rats subcutaneously (SC) injected or intracerebrally implanted with estradiol benzoate (EB), and given progesterone SC were used as experimental animals to assess the effects of the beta-endorphin (beta-EP) neuronal system on lordosis behavior. In intraventricular (IV) injection of beta-EP at the onset of sc EB priming, the lordosis behavior was significantly (p < 0.001) facilitated. In contrast, the lordosis behavior was significantly (p < 0.001) inhibited by IV injection of naloxone, an opioid receptor antagonist. beta-EP facilitation of lordosis was observed exclusively within the initial stage of estrogen action. The behavior was significantly (p < 0.001) facilitated by IV injection of beta-EP given with an intracerebral implantation of crystalline EB into the septal-preoptic regions. However, the lordosis behavior was significantly (p < 0.001) inhibited by beta-EP when EB was implanted into the ventromedial hypothalamus. Animals receiving EB implants into the mesencephalic reticular formation were not affected by beta-EP. The present study suggests that the beta-EP neuronal system stimulates sexual receptivity through an action on the central nervous system in relation to the site of estrogen-initial activation to induce the lordosis reflex. The sites of beta-EP action may be the estrogen receptive septal-preoptic and hypothalamic regions; the former for facilitatory effect and the latter for inhibitory effect.

Influence of opioid peptides on the priming action of estrogen on lordosis in ovariectomized rats

Lordosis in response to male mounting in estrogen-progesterone primed ovariectomized rats was facilitated by beta-endorphin or metenkephalin but inhibited by leu-enkephalin if the peptides were injected into third ventricle at the time of estrogen-priming. It is suggested that opioidergic systems modulate the activation of the estrogen-dependent brain functions that control lordosis.

Differential Effects of β-Endorphin and Met- and Leu-Enkephalin on Steroid Hormone-Induced Lordosis in Ovariectomized Female Rats

Abstract The effect of intrathirdventricular (ITV) injections of β-endorphin, anti-β-endorphin antiserum, Met-enkephalin, Leu-enkephalin, and naloxone on the initial activation and final development of steroid hormone-mediated induction of female sexual receptivity was studied in ovariectomized female rats. The lordosis response to male mounts in ovariectomized rats after subcutaneous (SC) estradiol benzoate (EB) and progesterone (Prog) priming was facilitated by β-endorphin, and Met-enkephalin (10 μg·5 μl −1 ), but inhibited by Leu-enkephalin, when the peptides were injected into the third ventricle at the time of SC EB priming. A lower dose Met-enkephalin had no effects. Lordosis behavior in steroid hormone-primed rats was significantly facilitated when ITV injections of Met-enkephalin were given 1 h prior to behavioral testing (47 h after EB priming). At 1 h prior to behavioral testing (47 h after EB priming), ITV injection of β-endorphin significantly inhibited lordosis behavior, especially at the higher dose of β-endorphin (10 μg·5 μl −1 ). Under those conditions, Leu-enkephalin had no effect. Lordosis behavior of ovariectomized female rats receiving SC steroid hormones and ITV injection of anti-β-endorphin antiserum was significantly inhibited when anti-β-endorphin antiserum was injected at the time of EB priming. However, lordosis was significantly facilitated when anti-β-endorphin antiserum was injected 1 h prior to the behavior testing (47 h after EB priming). In contrast, ITV injection of the opioid antagonist naloxone given either at the time of EB priming or 1 h prior to behavioral testing (47 h after EB priming) decreased lordosis behavior. The present results suggest that 1) β-endorphin, Met-enkephalin, and Leu-enkephalin have differential effects in the control of lordosis behavior; 2) the opioidergic systems may modulate initial-stage and final-stage estrogen-induced lordosis behavior; and 3) the opioidergic systems could be divided into the endorphinergic modulation-type and enkephalinergic modulation-type, based on their effects on lordosis behavior.

Changes in the lipid profile of blood serum in women taking sauna baths of various duration.

OBJECTIVES There is little information on lipid metabolism after sauna treatment in the literature. The present research is aimed to determine the influence of sauna baths on fat metabolism in young women. MATERIALS AND METHODS Twenty healthy, eumenhorreic, female volunteers (19-21 yr old) were exposed to Finnish sauna bath seven times every second day. In group I (n = 10) each time the sauna treatment lasted 30 min, whereas in group II (n = 10) 40 min with 5-minute break to cool down. Body mass, heart rate and blood pressure were measured before and after sauna bath. Rectal temperature was monitored during stay in sauna room. Prior to the sauna bath and during its last two minutes the minute oxygen uptake and the level of CO2 exhalation were analyzed in the exhaled air, and the respiratory quotient RQ was calculated. In the blood samples collected before the sauna bath and immediately afterwards hematocrit, hemoglobin, and lipid profile--total lipids, free fatty acids, total free fatty acids, triacylglycerols, total cholesterol (TC), high density lipids (HDL), low density lipids (LDL) were analyzed. RESULTS Rectal temperature was lower in the last sauna bath than in the first one. Losses of plasma were greater during the seventh bath than during the first one. Acceleration of the metabolism of lipids occurs after every sauna bath. A reduced level of TC and LDLC and a raised level of HDL was observed after repeated sauna baths. CONCLUSION After 2 weeks of repeated sauna session some changes in total cholesterol and concentration of LDLC were observed, while concentration of HDLC increased after 7th sauna bath in group I. Those kinds of changes may be good prognoses of ischemic heart disease prevention, but further research on the influence of sauna on fat metabolism is needed.

The influence of various methods of fluid ingestion on changes in selected physiological reactions during thermal stress in a sauna

Abstract The purpose of this experiment was to compare the influence of three different methods of fluid ingestion on selected physiological reactions during passive heating in a sauna. The participants were divided into three groups: group I (n=10) consumed a 4% glycerol solution (an average of 1860 ml) before entering the sauna; group II (n=10) consumed a nonrestricted amount of mineral water (an average of 1470 ml) whilst staying in, the sauna; group III (n=10) consumed 750 ml of water before night rest plus 750 ml of water prior to entering the sauna. The control group consisted of all participants (n=30) engaged in a one-time sauna exposure without consuming any fluids before or during the sauna session. Each sauna exposure involved a total time of 49 min: 3×15 min, of thermal heating in the sauna (95°C; relative humidity 26%), with two 2-min breaks for cooling. The lowest increases in rectal temperature and heart rate, as well as the smallest decrease of plasma volume were noted in subjects consuming water during the thermal exposure. The thermal sensations were also less pronounced during the heat exposure in this group. This data indicates that this system of hydration is likely to contribute to a more effective body heat elimination and better cardiac system functioning during the thermal exposition.

Effect of bilateral carotid cooling with an ice pack on thermal responses during bicycle exercise

We measured rectal, tympanic and skin temperatures, skin blood flow, local sweat rate and heart rate in seven healthy young men (mean age 25±3.7 yrs) during bicycle exercise for 40 min, with and without an ice pack provided after 20min of exercise. The primary objective was to observe whether partial body cooling is positively effective when thermoregulatory responses increase in hot ambient conditions (30°C, rh, 40%) at a given workload (60–70% of individuals aerobic work capacity). After ice cooling, tympanic temperature and local sweat rate were significantly decreased, and thermal sensation was significantly increased in comparison with the control. However, heart rate and skin blood flow were not significantly lower after ice cooling than in the control. There was no significant difference in the final rectal temperature with ice cooling. With ice cooling, the sweating sensitivity of the regression equation between local sweat rate and tympanic temperature showed a significant decrease in comparison with the control (F[1, 16]=62.67,p<0.001), and threshold temperature did not show a parallel shift. There were no significant differences in the sensitivity and threshold temperature in the skin blood flow vs. tympanic temperature relation in either experiment. The present results suggest that the effect of bilateral carotid cooling on the action of the thermal regulatory center may cause not only a decrease in wet-heat loss due to skin sweating but also reduction in the increase in tympanic temperature.