Sleep quality mediates the relationship between risk of obstructive sleep apnea and acute stress in young adults.

Intermittent hypoxia and transient arousals in obstructive sleep apnea (OSA) can lead to poor sleep quality and acute stress. Rising levels of obesity and increased incidence of OSA in young adults predisposes them to acute stress. We propose a mediation model to assess if risk of OSA is associated with acute stress and if the relationship between risk for OSA and acute stress is mediated by sleep quality. 493 healthy individuals (F = 237, M = 256) from 18 - 25 years of age (mean age 20.3 ± 1.53 years) were screened for OSA, sleep quality and acute stress using STOP-BANG questionnaire, Pittsburg Sleep Quality Index and American Psychiatry Association's National Stressful Events Survey Acute Stress Disorder Short Scale (NSESS-S), respectively. 73 participants (17.3%) were found at an intermediate and high risk of OSA by STOP BANG questionnaire. 79 (16%) participants reported level of stress as 'None'. Mild, moderate and severe stress was present in 248 (50.3%), 109 (22.1%), 51 (10.3%) and 16 (3.2%) participants, respectively. The odds of having severe and extreme stress among those at risk of sleep apnea is 2.18 times higher than that among those not at risk of sleep apnea (OR: 2.18, 95%, confidence interval: 1.37-3.51). Sobel test established that the relationship between OSA and acute stress is mediated by sleep quality. Sleep quality mediates the relationship between risk for sleep apnea and acute stress. This highlights the importance of screening for OSA in young adults, particularly young men with high BMI, presenting with high stress levels.

Homosexuality: a dilemma in discourse!

Homosexuality has been in practice even prior to its recorded history. In the Indian cultural context, discourse on sexuality had never gained an agreeable consensus from any platform. However, in the recent past, efforts were made by governmental and nongovernmental organizations to bring sex-related issues to the masses after speculation on presumably the fast spread of AIDS (acquired immuno-deficiency syndrome) particularly through illegal homosexual activities. Nevertheless, strong cultural and religious ideologies discouraged any valid discussions on homosexuality. In light of the given scenario, the present essay aimed to highlight several aspects of homosexuality that include a brief history, biological basis, effect of nature versus nurture, evolutionary perspective and related issues concerning general well-being and health.

The septal area, site for the central regulation of penile erection during waking and rapid eye movement sleep in rats: a stimulation study.

The effects of electrical stimulation to the septum on penile erections in rats were examined to clarify the mechanisms for regulation of erectile responses during different states of vigilance. Penile responses were assessed by changes in pressure in the corpus spongiosum of penis (CSP) and electromyography (EMG) of the bulbospongiosus (BS) muscle. In anesthetized and un-anesthetized rats, stimulation in and around the septum induced three erectile patterns; 1) a Normal type response, which was indistinguishable from a spontaneous erection, characterized by a slow increase in CSP pressure with sharp CSP pressure peaks associated with BS muscle bursts, 2) Mixed type response, in which high frequency CSP pressure peaks were followed by a Normal type response, and 3) a Prolonged type response, evoked only in the anesthetized rat, consisting of a single sharp CSP peak followed by a slow increase in CSP pressure and a return to baseline with multiple subsequent events repeated for up to 960 s. In addition, a Micturition type response was also observed involving high frequency CSP pressure oscillations similar to the pressure pattern seen during spontaneous micturition. We found that erections were induced after stimulation to the lateral septum (LS), but not from the medial septum (MS). In anesthetized rats, a few responses were also obtained following stimulation of the horizontal limb of diagonal band (HDB). In un-anesthetized rats, responses were also induced from the HDB and the ventral limb of diagonal band (VDB) and the adjoining areas. The effective sites for eliciting erection during rapid eye movement (REM) sleep were located in the dorsal and intermediate parts of the LS, whereas the ventral part of the LS was the most effective site for eliciting erections during wakefulness. These results suggest a functional role for penile erection in the septum, and further suggest that subdivisions of the LS may have different roles in the regulation of penile erection during wakefulness and REM sleep.

Brain areas activated after ejaculation in healthy young human subjects.

Brain mechanisms for the refractory period that characteristically follows ejaculation in animals and human are poorly understood. The possibility of active inhibition of brain areas being responsible for the post-ejaculatory inhibitory state has not been ruled out. Using Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) we have mapped brain areas in healthy young volunteers immediately after ejaculation. Functional imaging of the brain for 30 minutes beginning after three minutes of ejaculation induced by masturbation showed spatio-temporal activation in amygdala, temporal lobes and septal areas. The septal areas were observed to be active for a shorter duration than the amygdala and the temporal lobe. Thus the temporal sequence of involvement of the above neural structures may contribute to temporary inhibition of sexual arousal/penile erection during the post-ejaculatory refractory period in humans.

Understanding safety of glutamate in food and brain.

Glutamate is ubiquitous in nature and is present in all living organisms. It is the principal excitatory neurotransmitter in central nervous system. Glutamate is being used as food additive for enhancing flavour for over last 1200 years imparting a unique taste known as "umami" in Japanese. It is being marketed for about last 100 years. The taste of umami is now recognized as the fifth basic taste. Many of the foods used in cooking for enhancing flavour contain high amount of glutamate. Breast milk has the highest concentration of glutamate amongst all amino acids. Glutamate in high doses as gavage or parenteral injection have been reported to produce neurodegeneration in infant rodents. The neurodegeneration was not produced when gluamate was given with food. The Joint FAO/WHO Expert Committee on Food Additives, based on enumerable scientific evidence, has declared that, "glutamate as an additive in food" is not an health hazard to human being. Glutamate is used as signaling molecule not only in neuronal but also in non-neuronal tissues. Excessive accumulation of glutamate in the synaptic cleft has been associated with excitotoxicty and glutamate is implicated in number of neurological disorders. Excessive accumulation could be attributed to increase release, failure of transport system for uptake mechanism, neuronal injury due to hypoxia-ischemia, trauma and associated metabolic failures. The role blood brain barrier, vesicular glutamate and sodium dependent excitatory amino acid transporters in glutamate homeostasis are emphasized in the review.

Tonic activity of alpha1 adrenergic receptors of the medial preoptic area contributes towards increased sleep in rats.

Several studies have suggested that noradrenergic afferents to the medial preoptic area might be involved in hypnogenesis and in lowering the body temperature, and that the alpha1 adrenergic receptors might be mediating these responses. This study was undertaken to find out the changes in sleep-wakefulness and body temperature in rats, when these adrenergic receptors of the medial preoptic area are blocked by alpha1 selective antagonist, prazosin. Adult male Wistar rats were chronically implanted with electrooculogram, electroencephalogram and electromyogram electrodes for sleep-wakefulness assessment, and a bilateral guide cannula for microinjection of prazosin at the medial preoptic area. A radio-transmitter was implanted in the abdomen for telemetric measurement of body temperature in four groups of rats. Sleep-wakefulness was also assessed telemetrically in four other groups of rats. Sleep-wakefulness recordings from these rats were done in a specialized chamber, where they could move about freely and select the ambient temperature which they prefer. Prazosin induced a dose dependent increase in wake period and in body temperature, when microinjected into the medial preoptic area. Results suggest that preoptic alpha1 adrenergic receptors mediate hypnogenic and hypothermic responses. It is proposed that the noradrenergic afferents to the medial preoptic area, by tonic activation of alpha1 adrenergic receptors, contribute towards increase in sleep especially during the daytime.

Differences in the effects of medial and lateral preoptic lesions on thermoregulation and sleep in rats.

The effects of the destruction of the medial preoptic area and the lateral preoptic area with N-methyl-d-aspartic acid on sleep-wakefulness, brain temperature and thermoregulation were studied in two groups of male Wistar rats. Electroencephalogram, electrooculogram and electromyogram, along with brain temperature, were recorded for 3 days, prior to the destruction of the medial preoptic area and the lateral preoptic area, and on the 7th and 21st days after the destruction of these areas. The thermoregulatory capacity of the rats was assessed by recording their brain temperature when they were exposed to severe cold (5+/-1 degrees C) and heat (37+/-1 degrees C) before and after the lesion. Though sleep was decreased after the destruction of both the medial preoptic area and the lateral preoptic area, paradoxical sleep was reduced only by the destruction of the medial preoptic area. Decrease in sleep after the medial preoptic area lesion was brought about by a decrease in the duration of the slow wave sleep episodes and the frequency of paradoxical sleep episodes. Decrease in sleep after the lateral preoptic area lesion was brought about by a decrease in the frequency of slow wave sleep episodes. There was a significant increase in brain temperature after the medial preoptic area lesion but not after the lateral preoptic area lesion. The rats with lesion in the medial preoptic area showed deficits in thermoregulation on exposure to cold, while those with the lateral preoptic area lesion showed deficits in heat defense ability. The present findings suggest that the medial preoptic area and the lateral preoptic area regulate sleep by different modalities and that there is an anatomical segregation of heat and cold defense functions within the basal forebrain.

Atenolol or butoxamine injection at the lateral septum doesn't inhibit male sexual behavior in rats.

To investigate the role of specific adrenoreceptors subtypes on sexual behavior, atenolol, butoxamine, a mixture of atenolol and butoxamine, and saline (vehicle) were injected into the lateral septum in four different groups of sexually active male rats. Application of a mixture of atenolol and butoxamine produced inhibition of copulatory activity. On the other hand, application of either atenolol or butoxamine alone did not inhibit copulatory activity. But it produced stimulation of some of the components of male sexual behavior. Inability of either atenolol or butoxamine to inhibit the male sexual behavior, and inhibition of the same by the mixture of atenolol and butoxamine, indicate that both beta-adrenoreceptors at the lateral septum are involved in the elaboration of male sexual behavior. Stimulation of some components of sexual behavior on application of atenolol or butoxamine could be attributed to an unbalanced activity of beta-adrenoreceptors.

Functional MRI shows activation of the medial preoptic area during sleep.

Changes in the activity of the basal forebrain sleep regulating areas were studied noninvasively in conscious rats by employing functional magnetic resonance imaging (fMRI). Sleep-wakefulness (S-W) stages were identified with the help of electrophysiological recordings carried out simultaneously. An increase in the signal intensity was observed in the medial preoptic area (mPOA) during sleep indicating a heightened activity of neurons in this area. In some rats, there was a decrease in the activity of the fronto-parietal cortex. The sleep-induced increase in activity in the mPOA and decrease in the fronto-parietal cortex are in relation to their levels in the awake state. The findings helped to localize the critical area for the maintenance of slow wave sleep at the mPOA. These results further corroborate some of the previous suggestions based on neurotoxic lesion, chemical stimulation and electrophysiological recordings.

Gating of the dorsal penile nerve inputs by norepinephrine at the medial preoptic area in rats.

The medial preoptic area neurons related to male sexual behaviour in rats were identified by their responses to dorsal penile nerve stimulation. These neurons were further tested with norepinephrine applied iontophoretically. From the 21 medial preoptic area neurons recorded in urethane anaesthetized rats, 17 neurons responded to dorsal penile nerve stimulation. Excitatory and inhibitory responses were found in almost equal number of neurons. 14 neurons responded to norepinephrine application, out of which six neurons were excited and eight were inhibited. The direction of changes produced by dorsal penile nerve stimulation and norepinephrine application were similar in 10 neurons. The results suggest that the sensory inputs from the genitalia are possibly gated by norepinephrine at the level of the medial preoptic area. Afferent information from the genitalia carried by dorsal penile nerve and the availability of norepinephrine at the level of the medial preoptic area probably help in maintaining adequate level of sexual arousal.

Free glutamic acid content of milk in Indian mothers.

Free amino acids levels in the milk of 11 healthy Indian mothers were determined using automatic precolumn derivatization procedure. The aim of the study was to find out the relative concentration of glutamic acid and glutamine in the milk. Glutamic acid is the dominant free amino acid found in the milk of Indian mothers. Glutamic acid and glutamine together formed the major nonessential amino acids present in the human milk. Although glutamic acid has been shown to be the major amino acid in human milk in many studies, to the best our knowledge, this is the first report to confirm that glutamic acid is the most abundant amino acid in milk in Indian mothers.

Stereotaxic assembly and procedures for simultaneous electrophysiological and MRI study of conscious rat.

A stereotaxic restraining assembly was designed and developed for simultaneous electrophysiological recordings and functional MRI (fMRI) data acquisition from a conscious rat. The design of the nonmagnetic stereotaxic apparatus facilitated the restraining of head and body of the unanesthetized conscious animal during MRI experiments. The apparatus was made of Teflon and Perspex materials with an appropriate size and shape for a 4.7 T / 40 cm animal MRI scanner. Electrodes made from nonmagnetic silver wire were implanted on the skull for recording the electroencephalogram (EEG), the electro-oculogram (EOG), and the electromyogram (EMG), while polycarbonate screws were used for anchoring the electrode assembly. There were no major distortions or artifacts observed in the electrophysiological tracings and MR images. Electrophysiological recordings during fMRI acquisitions are useful to study different neurophysiological mechanisms of sleep and pathophysiology of seizure activity. Integration of electrophysiological recordings (with their good temporal resolution) and MRI (with its superior spatial resolution) is helpful in characterizing the functional state of different brain regions.

Orexin A (hypocretin-1) application at the medial preoptic area potentiates male sexual behavior in rats.

The medial preoptic area plays an important role in the regulation of male sexual behavior in rats, and this area receives orexinergic inputs. The role of orexinergic inputs in the medial preoptic area in sexual behavior has not been studied, though they have been shown to play a role in some other physiological functions. In this study, the changes in male sexual behavior in rats were studied after local injection of orexin A (Hypocretin-1) at the medial preoptic area. The results of the study showed that orexin A application at the medial preoptic area increased sexual arousal as well as the copulatory performance. Sexual arousal is one of the physiological stimuli, which influences wakefulness. It is possible that the earlier reports showing increased wakefulness, on application of orexin A at the medial preoptic area/basal forebrain, has a contribution from sexual arousal.

Role of the medial preoptic area in thermal preference of rats.

This study was conducted to find out whether the medial preoptic area (mPOA) plays a role in the selection of ambient temperature by rats. Adult male Wistar rats were kept in an environmental chamber having three interconnected compartments, maintained at three different temperatures (18 degrees, 24 degrees and 30 degrees C) in which the animals could move freely from one compartment to the other. Normal rats preferred to stay at the chamber maintained at 24 degrees C for most of the time, during day and night. The temperature preference shifted to 30 degrees C after the mPOA of these rats had been lesioned by local administration of 5 micrograms of N-methyl D-aspartic acid (NMDA) in 0.2 microliter distilled water. The results of the study suggest that the mPOA acts as a fine tuning center for homeostatic regulation of thermal balance, including selection of appropriate thermal environment. It is proposed that after the mPOA lesion, the animal cannot assess properly the energy status of the body and thereby prefers a higher ambient temperature.

Review of Prof. B.K. Anand's scientific study: fifty years following his discovery of feeding centre.

Prof. BK Anand the living legend, is the founder of modern neurophysiology in India. His career spanned an era that marks the beginning of Brain Research in India. His contributions to understanding of brain functions began with the epoch making discovery of lateral hypothalamic area as the 'feeding center'. Subsequently it encompasses a wider range of studies from elucidation of the intricate mechanisms underlying ingestive behaviour to hypothalamic regulation of cardiovascular, respiratory, gastrointestinal activity and regulation of various physiological functions by limbic system. The following review gives an account of the contributions made by Prof Anand and his colleagues during twenty five years of his illustrious career. The publications resulted from his studies has not only stood as a testimony to understanding of the neural control of ingestive behaviour and limbic functions but also have been a sources of a great interest to those who pursue knowledge in this field.

beta-adrenergic modulation of male sexual behavior elicited from the medial preoptic area in rats.

This study was aimed at investigating the role of the adrenergic mechanism in the medial preoptic area (mPOA) in sexual arousal and copulatory performance. Saline, norepinephrine (NE), phenoxybenzamine (PBZ) and propranolol (PROP) were injected into the mPOA in different groups of rats. NE application (3 micrograms) facilitated the male sexual behavior by increasing sexual arousal and copulatory performance. On the other hand, application of PROP and PBZ produced inhibition of male sexual behavior. Effects produced by low doses of PROP were more significant than PBZ. The results, viewed in the light of other available reports, suggest that the mPOA beta-adrenergic mechanism is important in the elaboration of male sexual behavior.

Medial preoptic alpha-2 adrenoceptors in the regulation of sleep-wakefulness.

Adrenergic alpha 2 agonist (clonidine) and its antagonist (yohimbine) were locally applied to the medial preoptic area (mPOA), to find out the role of alpha 2 receptors at this brain region in the regulation of sleep-wakefulness. Clonidine produced arousal, whereas yohimbine induced sleep in freely moving animals. Behavioural arousal produced by clonidine administration was accompanied by EEG synchronization. The alpha 2 receptor as the probable site of action of externally applied norepinephrine (NE), is discussed.

Sensory modulation of the medial preoptic area neuronal activity by dorsal penile nerve stimulation in rats.

The study was aimed at finding out the influence exerted by the genital afferents on the medial preoptic area (mPOA), which plays a pivotal role in the regulation of male sex behavior. To fulfil this objective, the effects of stimulation of the dorsal penile nerve (DPN) on the activity of 82 mPOA neurons were studied. The base line firing rates of the mPOA neurons, studied by extracellular recording, ranged between 0.5 and 38.5 Hz (mean 7.18 +/- 7.91). The stimulation of the DPN (20 Hz, 0.4 msec. 70 microA) influenced 79.69% of the neurons studied. Though increased firing was the predominant influence produced (50%), decreased firing was also seen in a few (29.69%). The excited and inhibited neurons were randomly distributed within the mPOA. Neurons located in the lateral and posterior hypothalamus were not affected by the DPN stimulation. The stimulation parameters used in this study did not produce any change in the systemic arterial pressure and heart rate. The results provide electrophysiological evidence of afferent inputs from the male sex organ to the mPOA, which is an important area controlling male sex behavior.

Changes in sleep-wakefulness after kainic acid lesion of the preoptic area in rats.

The role of the preoptic area (POA) neurons in the regulation of sleep-wakefulness (S-W) has been investigated in this study. The cell-specific neurotoxin, kainic acid (KA), was injected (0.8 microgram in 0.2 microliter) intracerebrally for lesioning of the POA. S-W was assessed (on the basis of EEG, EMG, and EOG recordings) for a day before bilateral lesion of the POA, and for 3 weeks after the lesion. There was an increase in wakefulness, and a decrease in all the stages of sleep after KA lesion of the POA. The reduction in deep slow wave sleep (S2) and REM sleep (PS) were more marked than light slow wave sleep (S1), and these had not shown any recovery even after 3 weeks of lesion. Two days after the lesion, the reduction in sleep was much more marked during the daytime than at night. There was an increase in locomotor activity, especially during the daytime, though it was only statistically significant on the 6th and the 10th day after the lesion. This study shows that the POA neurons are involved in the induction and maintenance of sleep. The lesion did not have a long lasting effect on the circadian distribution of sleep but the changes in locomotor activity seem to persist for a longer period.