Insidious weight gain in prepubertal seized rats treated with an atypical neuroleptic: the role of food consumption, fluid consumption, and spontaneous ambulatory activity.

Extreme obesity slowly develops in female rats over the months following seizures induced by a single systemic injection of lithium and pilocarpine if the resulting limbic seizures are treated with the atypical neuroleptic acepromazine (but not with ketamine). To discern the contributions from food consumption, water consumption, and (daytime and nighttime) activity to this weight gain, these behaviors were monitored for 4 months, about 2 months after seizure induction. The results indicated that the rats that underwent the obesity procedure exhibited 50% heavier body weights and consumed 42% more food than the reference group, which included rats that had been induced to seize but treated with ketamine. There were no statistically significant differences between groups with respect to either water consumption or (daytime or nighttime) activity. Factor analyses of data for individual rats verified the dissociation between activity and weight gain for the obese rats. The results suggest that the progressive weight gains are centrally mediated and are not secondary to diminished activity or altered fluid consumption.

Enhanced mortality of rat pups following inductions of epileptic seizures after perinatal exposures to 5 nT, 7 Hz magnetic fields.

While investigating the effects of weak complex magnetic fields upon neuroplasticity following induction of early epilepsy, an unprecedented increase in post-seizure mortality (76%) was observed for young rats that had been exposed perinatally to 7 Hz magnetic fields with maximum intensities around 5 nT. Pups exposed to less intense or more intense fields of this frequency did not display this magnitude of significant mortality. Perinatal exposure through the maternal water supply to either a putative nitric oxide donor or inhibitor did not affect this mortality. The non-linear relationship between perinatal 7 Hz magnetic field intensity and post-seizure mortality may be considered analogous to the non-linear relationship between the molarity of ligands and their sequestering to receptor subtypes. These unexpected results suggest that exposure to apparently innocuous stimuli during early development may affect vulnerability to stimuli presented later in ontogeny.

Role of melatonin in upper gastrointestinal tract.

Melatonin, an indole formed enzymatically from L-tryptophan, is the most versatile and ubiquitous hormone molecule produced not only in all animals but also in some plants. This review focuses on the role of melatonin in upper portion of gastrointestinal tract (GIT), including oral cavity, esophagus, stomach and duodenum, where this indole is generated and released into the GIT lumen and into the portal circulation to be uptaken, metabolized by liver and released with bile into the duodenum. The biosynthetic steps of melatonin with two major rate limiting enzymes, arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT), transforming tryptophan to melatonin, originally identified in pinealocytes have been also detected in entero-endocrine (EE) cells of GIT wall, where this indole may act via endocrine, paracrine and/or luminal pathway through G-protein coupled receptors. Melatonin in GIT was shown to be generated in about 500 times larger amounts than it is produced in pineal gland. The production of melatonin by pineal gland shows circadian rhythm with high night-time peak, especially at younger age, followed by the fall during the day-light time. As a highly lipophilic substance, melatonin reaches all body cells within minutes, to serve as a convenient circadian timing signal for alteration of numerous body functions.. Following pinealectomy, the light/dark cycle of plasma melatonin levels disappears, while its day-time blood concentrations are attenuated but sustained mainly due to its release from the GIT. After oral application of tryptophan, the plasma melatonin increases in dose-dependent manner both in intact and pinealectomized animals, indicating that extrapineal sources such as GIT rather than pineal gland are the major producers of this indole. In the upper portion of GIT, melatonin exhibits a wide spectrum of activities such as circadian entrainment, free radicals scavenging activity, protection of mucosa against various irritants and healing of various GIT lesions such as stomatitis, esophagitis, gastritis and peptic ulcer. This review concentrates on the generation and pathophysiological implication of melatonin in upper GIT.

Localization and biological activities of melatonin in intact and diseased gastrointestinal tract (GIT).

Melatonin (MT), an indole formed enzymatically from L-trytophan (Trp), was first discovered in the bovine pineal gland in 1958 by Lerner et al. Melatonin is the most versatile and ubiquitous hormonal molecule produced not only in the pineal gland but also in various other tissues of invertebrates and vertebrates, particularly in the gastrointestinal tract (GIT). This review focuses on the localization, production, metabolism and the functions of MT in GIT and the duodenal unit (liver, biliary routes and pancreas), where multi-step biosynthetic pathways of this indole, similar to those in pinealocytes, have been identified. These biosynthetic steps of MT, including two major rate limiting enzymes; arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT), transforming L-tryptophan (Trp), originally identified in pinealocytes, have been also detected in entero-endocrine (EE) cells of GIT, where this indole appears to act in endocrine, paracrine and/or luminal pathway directly or through G-protein coupled MT receptors. Studies of the distribution of MT in GIT mucosa showed that this indole is generated in GIT in much larger amounts than it is produced in the pineal gland. Melatonin acts in GIT, partly locally in paracrine fashion and is partly released into portal circulation, to be taken up by the liver. It is then metabolized and excreted with the bile to small bowel and finally returns to liver through entero-hepatic circulation. The production of MT by the pineal gland shows circadian rhythm with high night-time surge, especially at younger age, followed by the fall during the day-light time. As a highly lipophylic substance, MT reaches all body cells within minutes, thus, serving as a convenient circadian timing signal. Following pinealectomy, the light/dark cycle of plasma MT levels disappears, while its day-time blood concentration is maintained mainly due to its release from the GIT. According to our experience, after oral application of Trp, the plasma MT increases in dose-dependent manner both in intact and pinealectomized animals and humans, indicating that GIT but not the pineal gland is a source of this indole. In GIT MT exhibits a wide spectrum of activities such as circadian entrainment, antioxidant and free radicals scavenging activity, Melatonin (MT), an indole formed enzymatically from L-trytophan (Trp), was first discovered in the bovine pineal gland in 1958 by Lerner et al. Melatonin is the most versatile and ubiquitous hormonal molecule produced not only in the pineal gland but also in various other tissues of invertebrates and vertebrates, particularly in the gastrointestinal tract (GIT). This review focuses on the localization, production, metabolism and the functions of MT in GIT and the duodenal unit (liver, biliary routes and pancreas), where multi-step biosynthetic pathways of this indole, similar to those in pinealocytes, have been identified. These biosynthetic steps of MT, including two major rate limiting enzymes; arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT), transforming L-tryptophan (Trp), originally identified in pinealocytes, have been also detected in entero-endocrine (EE) cells of GIT, where this indole appears to act in endocrine, paracrine and/or luminal pathway directly or through G-protein coupled MT receptors. Studies of the distribution of MT in GIT mucosa showed that this indole is generated in GIT in much larger amounts than it is produced in the pineal gland. Melatonin acts in GIT, partly locally in paracrine fashion and is partly released into portal circulation, to be taken up by the liver. It is then metabolized and excreted with the bile to small bowel and finally returns to liver through entero-hepatic circulation. The production of MT by the pineal gland shows circadian rhythm with high night-time surge, especially at younger age, followed by the fall during the day-light time. As a highly lipophylic substance, MT reaches all body cells within minutes, thus, serving as a convenient circadian timing signal. Following pinealectomy, the light/dark cycle of plasma MT levels disappears, while its day-time blood concentration is maintained mainly due to its release from the GIT. According to our experience, after oral application of Trp, the plasma MT increases in dose-dependent manner both in intact and pinealectomized animals and humans, indicating that GIT but not the pineal gland is a source of this indole. In GIT MT exhibits a wide spectrum of activities such as circadian entrainment, antioxidant and free radicals scavenging activity, cytoprotective, anti-inflammatory and healing efficacy of various GIT lesions such as esophagitis, gastritis, peptic ulcer, pancreatitis and colitis. This review concentrates on the generation and pathophysiological implication of MT in GIT and related organs.

Chronomics reveal and quantify circadian rhythmic melatonin in duodenum of rats.

A circadian rhythm is documented in duodenal melatonin in rats, peaking 16.8 hours after light onset. This component is more readily detected after log10-transformation of the data. It differs between male and female rats, females having a larger circadian amplitude and an earlier acrophase. The circadian rhythm in duodenal melatonin is also found to lead that of pineal melatonin. The results are qualified by the presence at the start of mapping of the second extremum of a double magnetic storm.

Chronomics: circadian lead of extrapineal vs. pineal melatonin rhythms with an infradian hypothalamic exploration.

A circadian rhythm is documented for plasma, pineal, and hypothalamic melatonin of male and female rats kept on staggered lighting regimens. Log[_10]-transformation of the data usually normalizes, when need be, the distribution of residuals from the 24-hour cosine curve fits. A tentative circadian acrophase chart is presented that shows a lead in circadian acrophase of duodenal over pineal melatonin. The use of antiphasic lighting regimens facilitates circadian studies that can be carried out for several days, thereby allowing the assessment of infradian components such as a circasemiseptan variation in hypothalamic melatonin documented herein. The results are qualified by the presence of a second extremum of a double magnetic storm at the start of mapping.

Chronomics affirm extending scope of lead in phase of duodenal vs. pineal circadian melatonin rhythms.

In Göttingen, Germany, circadian variations in melatonin had been determined time-macroscopically in pineal glands, blood plasma and duodenum of chicken and rats. When these data were meta-analyzed, they agreed with the results from an independent survey on tissues from rats collected in a laboratory in Pécs, Hungary. In the latter study, tissues were analyzed chemically in Bratislava, Slovakia, and numerically in Minneapolis, MN, USA, all by single- and multiple-component cosinor and parameter tests. In rats and chickens, these inferential statistical procedures clearly demonstrated a lead in phase of the 24-h cosine curves best fitting all of the duodenal vs. those best fitting all of the pineal melatonin values in each species in 2 geographic (geomagnetic) locations. The 24-h cosine curve of circulating melatonin was found to be in an intermediate phase position. Mechanisms of the phase differences and the contribution of gastrointestinal melatonin to circulating hormone concentrations are discussed.

Chronomics, neuroendocrine feedsidewards and the recording and consulting of nowcasts--forecasts of geomagnetics.

A multi-center four-hourly sampling of many tissues for 7 days (00:00 on April 5-20:00 to April 11, 2004), on rats standardized for 1 month in two rooms on antiphasic lighting regimens happened to start on the day after the second extremum of a moderate double magnetic storm gauged by the planetary geomagnetic Kp index (which at each extremum reached 6.3 international [arbitrary] units) and by an equatorial index Dst falling to -112 and -81 nT, respectively, the latter on the first day of the sampling. Neuroendocrine chronomes (specifically circadian time structures) differed during magnetically affected and quiet days. The circadian melatonin rhythm had a lower MESOR and lower circadian amplitude and tended to advance in acrophase, while the MESOR and amplitude of the hypothalamic circadian melatonin rhythm were higher during the days with the storm. The circadian parameters of circulating corticosterone were more labile during the days including the storm than during the last three quiet days. Feedsidewards within the pineal-hypothalamic-adrenocortical network constitute a mechanism underlying physiological and probably also pathological associations of the brain and heart with magnetic storms. Investigators in many fields can gain from at least recording calendar dates in any publication so that freely available information on geomagnetic, solar and other physical environmental activity can be looked up. In planning studies and before starting, one may gain from consulting forecasts and the highly reliable nowcasts, respectively.

Localization of immunoreactive androgen in testicular tissue.

Immunohistochemical localization of androgen in the testes of both rat and squirrel monkey has been performed using an antiserum specific to testosterone and certain related androgens. The bound antibodies were visualized by coupling with antigammaglobulin labeled either with fluorescein isothiocyanate or with a horseradish peroxidase-diaminobenzidine technique. The highest concentration of androgen was found in the interstitial tissue but a significant amount was also present in the seminiferous tubules in the layer adjacent to the tubular wall. Very small amounts of androgen were localized in the tubular wall. This restricted localization in the tubules might indicate either de novo synthesis or active uptake of steroids intermediate in the biosynthesis of testosterone in the seminiferous tubules.

Epileptogenic action of intraventricularly injected antimelatonin antibody.

In rats, intraventricularly injected antimelatonin antibody caused the appearance of transitory epileptiform abnormalities. Epileptic activity arose from and was limited to the cortical mantle of the hemisphere ipsilateral to the injection side. The occasional occurrence of lateralized seizures has also been observed. Control injection of saline, of the vehicle (rabbit serum), or of antibody saturated with melatonin induced flattening and desynchronization of the electroencephalogram but not epileptiform activity. Repeated antimelatonin injections caused reappearance of the same type of epileptic abnormalities that lasted slightly longer than the first time. Melatonin may play an inhibitory role in neuronal excitability.

Immunohistochemical localization of melatonin in the rat Harderian gland.

Using fluorescence and double antibody techniques, melatonin was localized immunohistologically in the secretory cells of the Harderian gland of mature male rats. The presence and quantity of melatonin in the acinar cells seem to correlate with the amount of porphyrins inside the lumen. The specificity was proven by disappearance of yellow fluorescence after saturation of antibody with melatonin or after use of nonspecific antibody only.

Cyproterone acetate reduced antler growth in surgically castrated fallow deer.

We studied the role of androgens in antler growth. In particular, we investigated whether the onset of antler regrowth is triggered by a short-term pulse of testosterone and if low levels of androgens are required for antler growth. The study was conducted on 12 surgically castrated fallow deer bucks (Dama dama) aged approximately 27 months. Six animals (CA group) were given the antiandrogen, cyproterone acetate (CA, 1000 mg/treatment); the others were given vehicle solution only (control). Before each CA treatment, blood was sampled and analysed for testosterone, androstenedione, IGF-1, cortisol, FSH, and LH. CA treatment and blood sampling were performed 2 days before castration, on the day of castration and afterwards at 2-day intervals until day 22. Subsequently, CA treatment and blood sampling continued at weekly intervals until day 270. All animals cast their antlers, followed by antler regrowth in all control bucks, but in only four of the six CA-treated castrates. Plasma testosterone concentrations were low in all animals (between 0.01 and 0.20 ng/ml), but were significantly (P<0001) greater in the controls. In both groups, a temporary increase in testosterone values was recorded around the time of antler regrowth, the peak being significantly (P<0.01) higher in the controls. Androstenedione showed a similar pattern as testosterone. Plasma IGF-1 concentrations increased sharply during the antler growth spurt and did not differ significantly between the two groups throughout the study period. Cortisol concentrations were greater in controls than in the CA group. However, no link with the antler cycle was apparent. FSH and LH concentrations were higher in the controls for most of the study. Antlers produced by the control bucks were significantly larger than those in the CA group (P<0.03). For antler length, testosterone, androstenedione and IGF-1, areas under the curve (AUC) were calculated over the period of antler growth. For the pooled deer (n=12) significant correlations existed between AUCs of antler length and testosterone, but not for antler length and IGF-1. Also, a trend for a positive correlation between AUCs of antler length and androstenedione was noted. It is concluded that a plasma androgen concentration at least above a minimal threshold level is a necessary prerequisite for normal antler regrowth in fallow deer, and that this androgen effect is not mediated via circulating IGF-1. The biological role of low levels of androgens may be to sensitize antler cells to the stimulating effect of IGF.

Differential localization of N-acetylated indolealkylamines in CNS and the Harderian gland using immunohistology.

Using two different antisera, one binding only melatonin (M) and the other binding both M and N-acetylserotonin (NAS), brain tissue and the Harderian gland were investigated using fluorescence and peroxidase labeled double antibody immunohistology. M has been identified in the outer nuclear layer of the retina, in the optic nerves, chiasma and the tracts, suprachiasmatic nucleus and the Harderian gland. NAS, but not M, was found in the granule layer of the cerebellum, spinal tract of the trigeminal roots and the pontal and spinal reticular formation. The possible relationship of cerebellar and brain stem NAS to brain excitability as well as localization of M in the visual pathway, suprachiasmatic nucleus and the Harderian gland in the relation to the regulation of light dependent circadian periodicity is discussed.

Melatonin-induced changes in the sensory activation of acute epileptic foci.

Intraperitoneal, intravenous and intracisternal injection of various amounts (50-1000 microg/kg) of melatonin in cats did not significantly change the focal epileptiform activity produced in various cortical areas and limbic structures by topical application of various convulsant agents. However, when the focus was located in primary sensory areas the sensory evoked activation of the epileptiform activity was reduced or suppressed. The present report and other literature data support the hypothesis that melatonin may change the response of epileptic neurons to sensory stimuli.

Seasonal levels of reproductive hormones and their relationship to the antler cycle of male and female reindeer (Rangifer tarandus).

Seasonal levels of LH, FSH, testosterone (T), estradiol, progesterone (P), and prolactin (PRL) were determined in the plasma of five adult bulls, and five barren and four pregnant cows of Alaskan reindeer (Rangifer tarandus), which were sampled every 3 weeks for 54 weeks. The male reproductive axis was sequentially activated; LH peaked in May-June (2 ng/ml), FSH in June (51 ng/ml), and T in September (11.8 ng/ml). LH levels in females reached a maximum in both groups at the end of August (the beginning of the rut). Seasonal variation in FSH was minimal in pregnant cows, but exhibited one elevation (41 ng/ml) in barren ones in November. T levels in cows remained at barely detectable levels. The decrease of T values observed in both groups in December and March was not significant. PRL peaked in May in cows (135 ng/ml pregnant, 140 ng/ml non-pregnant) and in June in bulls (92 ng/ml). Estradiol was highest in bulls in the rut (August), in non-pregnant cows in January and in pregnant cows in April, shortly before parturition. P levels in the pregnant cows rose from September and peaked (9 ng/ml) shortly before parturition in April. In the non-pregnant females P values increased and decreased several times before peaking (5 ng/ml) in March. In the males, the variation of T and estradiol levels correlated relatively well with the antler cycle but in the females the variation of neither estradiol, progesterone nor T appeared to be related to mineralization or casting of antlers.

The effect of ACTH on the GnRH-induced release of LH and testosterone in male white-tailed deer.

In order to investigate the possible link between stress and the impairment of the reproductive system, 12 yearling white-tailed bucks, born to mothers captured wild in southern Texas, were immobilized every 6 weeks over the period of 1 year. In half of experiments deer were injected i.m. with 20 i.u. of ACTH; in the second half, we used saline only. Simultaneously, in each experiment we also injected all deer i.m. with 100 micrograms of GnRH. Three blood samples were taken before and seven after treatment and plasma levels of cortisol, LH and testosterone (T) were later measured by RIA. Half of our yearlings were born to mothers which were fed high-protein-high-energy (HP-HE) diet during their pregnancy; the other half ws fed high-protein-low-energy diet (HP-LE). ACTH increased cortisol levels in both nutritional regimes. Cortisol levels in controls decreased with time but a more pronounced reduction was observed in HP-HE bucks as compared to HP-LE deer. GnRH significantly increased LH and T levels. However, only in summer, LH levels were higher in HP-LE fed deer than those fed HP-HE; in other seasons they were equal. Conversely, only in winter T levels were elevated in HP-HE fed deer as compared with HP-LE deer. We concluded that the pronounced suppression of reproductive hormones by ACTH or cortisol reported previously in domestic ungulates does not occur in white-tailed deer yearlings. Conversely, the low level of energy provided in food to mothers during their pregnancies significantly reduced peak levels of testosterone in their male offspring. This study further proved that white-tailed deer is a highly adaptable cervid species resistant to environmental stress.

Seasonal levels of metabolic hormones and substrates in male and female reindeer (Rangifer tarandus).

Seasonal levels of cortisol, growth hormone (GH), insulin like growth factor 1 (IGF-1), glucose, triiodothyronine (T3), free T3, thyroxine and free fatty acids (FFA) were measured every 3 weeks for 54 weeks in the plasma of five adult bulls, and four barren and five pregnant Alaskan reindeer (Rangifer tarandus) cows. Three consecutive samples were taken from each animal. Cortisol levels exhibited wide seasonal variation (9-45 ng/ml) [corrected] without any peak or difference in levels among groups. Rising levels were detected between the 3 consequent samples. Peak GH levels, detected during January and February, were higher in the non-pregnant group (54 ng/ml) than the pregnant (26 ng ml-1) and the male (27 ng ml-1) groups. Low GH levels (2-10 ng ml-1) were recorded between May and September. IGF-1 reached peak levels (715 ng ml-1) in males in August, in non-pregnant females in September (677 ng ml-1), and in the pregnant females in October (505 ng ml-1). Seasonal minima (404 in males, 172 and 93 in pregnant and non-pregnant groups) were detected in February. Glucose was fairly stable throughout the year (100-200 mg/100 ml). A rising levels were found between the three consecutive samples. Triiodothyronine (T3) (2.16-2.30 ng ml-1) peaked in all three groups during the spring and early summer, and minimal levels (0.61-0.97 ng ml-1) were detected from October to January. Conversely, thyroxine or free T3 did not exhibit seasonal variation. FFA fluctuated widely (97-1076 nmol l-1) throughout the year. Only in pregnant females were concentrations more stable (150-460 nmol l-1). Perhaps, because of ad libitum supply of food in captive reindeer, only T3 and GH exhibited pronounced seasonal fluctuations which could be related to the metabolic changes expected during the annual cycle.

Can androgen deficiency promote an outbreak of psoroptic mange mites in male deer?

Repeated outbreaks of infection by psoroptic mange mites (Psoroptes equi var. ovis) affecting most regions of the body and legs were observed in several male white-tailed deer (Odocoileus virginianus) suffering from hypoandrogenism (e.g., castrates, animals treated with antiandrogens or postprime). The massive infection was characterized by a severe alopecia and skin inflammation and began usually in early winter. One or two spray treatments of a 1% solution of Lindane was usually sufficient to eliminate the clinical signs of the disease and to restore a healthy hair coat. Neither healthy male or female deer have ever exhibited any external signs of this disease nor has the parasite been detected in the scrapings of their skin. We propose a possible relationship between the hormonal status of these animals and their resistance to this parasitic mite infection.

Congenital osteopetrosis in white-tailed deer (Odocoileus virginianus).

Inferior brachygnathia in neonatal fawns occurred sporadically over a 10 yr period in a captive herd of white-tailed deer (Odocoileus virginianus) in southern Ontario. Two fawns submitted for necropsy had marked inferior brachygnathia, protruding tongues, and fractured long bones. Radiographs of the limbs revealed longitudinal striations of relatively translucent immature woven bone that caused loss of distinction between medullary cavities and cortices. Microscopically, there was failure of remodelling of the primary spongiosa and filling of the medulla by cone-shaped chondro-osseous cores. The findings supported a diagnosis of osteopetrosis, usually a hereditary disease characterized by absence of marrow cavities as a result of defective bone remodelling. Osteopetrosis has not been reported previously in deer.

Melatonin and aging: prospects for human treatment.

Human life span, with or without modern medicine is around 85-95 years. All living creatures have their inner clock that measures their daily (circadian) and their seasonal (circannual) time. These time changes are mediated by the alteration of levels of melatonin, an evolutionary ancient hormone, which is produced in many body tissues, including the pineal gland, retina and the gastrointestinal tract (GIT). Light is blocking the production of melatonin in the pineal gland, darkness is stimulating it. So, the diurnal changes of light intensity of melatonin, provide a "daily clock" and the seasonal changes provide a "seasonal clock". Finally, the reduction of melatonin observed with aging, may indicate the presence of an "age clock". Melatonin is a strong antioxidant (often it is called scavenger of free radicals), which protects the body from the effects of noxious compounds. Therefore it was hypothesized that the reduction of melatonin levels with age contributes to the aging process. So far, the only remedy to extend the life span was a 40% reduction in caloric intake, which prolonged the life in mice, rats, dogs and monkeys by 30-50%. A large group of people imitate these experiments performed on animals, but the results of these experiments will not be known for several decades. How is being hungry prolonging the life span? There is a connection between caloric reduction and melatonin levels in GIT. Several experiments indicate that fasting in animals substantially increased their production of GIT melatonin. Therefore, instead of being permanently hungry, a prolongation of human life could be achieved by a replacement melatonin therapy. A daily intake of melatonin before bed time might achieve the same effect as fasting e.g. an increase of body melatonin levels, which will protect the individual from the ravages of old age. That includes Parkinson's disease and Alzheimer's disease. There is a large group of people taking melatonin daily who believe that melatonin is the "fountain of youth". Those are the subjects which will one day provide an experimental evidence of the efficacy of melatonin.