Stereometric observations on the hypothalamic neurosecretory system of the spotted owlet, Athene brama Temminck, in total preparations.

The configuration of the HNS of the spotted owlet, Athene brama Temminck, was studied by employing the bulk-staining technique. This enabled a three-dimensional view of the HNS. The neurons of the SON are distributed into three divisions, namely, the preoptic, median and lateral. The PVN is U-shaped; the distal portion of the arms of the U extends laterally to form the lateral division of the PVN, which remains in continuity with the lateral division of the SON. The periventricular division of the PVN joins ventrally the median division of the SON. Unlike in the passerine birds, in the spotted owlet the PVN is more prominently developed than the SON. Since the axonal pathways are not stained, the proximal portion of the hypothalamo-hypophysial tract could not be demonstrated in bulk-stained preparations. Hence it was not possible to trace with certainty the origin of the axonal terminations in the ME and in the NL. Anterior of the ME, the tract branches into two; one branch enters the zona externa to the ME and the other is continued into the NL. The ME is divisible into an AF-positive anterior region and an AF-negative posterior region. The NL is saccular and heavily loaded with the NSM. Studies on the HNS of the spotted owlet by the bulk-staining technique reveal that the general configuration of the system is comparable to that of the HNS of birds studied previously.     

Antagonistic response of chlorpromazine and formalin in effecting quantitative changes in the neurosecretory material in the teleost Clarias batrachus (L.).

The hypothalamoneurohypophysial complex of Clarias batrachus maintains an appreciable quantity of neurosecretory material (NSM) under normal conditions. Stress caused by the injection of formalin depletes 70-90% of the stainable NSM from all the component parts of the neurosecretory system, namely the nucleus preopticus (NPO) the neurosecretory tract, and the neurohypophysis. Formalin apparently releases the NSM and stimulates the neurons of the NPO. Chlorpromazine (CPZ) treatment seems to cause quantitative increase of NSM throughout the neurosecretory complex. Simultaneous injection of CPZ and formalin showed that the formalin-induced depletion of NSM could be inhibited by CPZ.     

巴基斯坦旁遮普中部横斑腹小鸮的食性

横斑腹小鸮(Athene brama)是巴基斯坦旁遮普中部农业生态系统中最常见但研究匮乏的猛禽。我们通过分析吐弃块(n=498)以了解其季节性和地域性食性变化。结果显示:小型哺乳类占所有食物生物量的98.4%,而昆虫类在数量上占据绝对优势(56.4%)。在小型哺乳类食物中,鼠类(38.8%)是稳定的食物成分。而在昆虫食物中,甲虫最多(42.8%)。横斑腹小亦捕食鼩鼱类(2.3%)和鸟类(1.7%)。昆虫类食物还有蟑螂(6.4%)、臭虫(3.3%)、蝗虫(6.7%)和蚂蚁(3.2%)。小家鼠(Mus musculus)和柔毛鼠(Rattus meltada)在鼠类食物中出现频次最多。不同地区中,Hafizabad的食物多样性最高(2.07),而秋季的食物多样性最高(1.99)。     

Time and reproductive phase-dependent effects of exogenous melatonin on the pineal gland and ovary of a nocturnal bird, the Indian spotted owlet, Athene brama

In a tropical nocturnal bird, the Indian spotted owlet, Athene brama, the intraperitonial injection of an identical amount (20 mg/100 g b. wt/day) of exogenous melatonin (MEL) for 15 consecutive days increased the pineal weight and plasma MEL level in sexually active birds while it decreased them in inactive birds more potently when injected in the evening (18.30-19.30 h) rather than the morning (0500-0600 h). On the other hand, more efficiently than the morning hour treatment, the evening hour MEL injection decreased the ovary weight and plasma estradiol and progesterone levels both in sexually active and inactive birds, but more potently in active than inactive birds. Thus, the exogenous MEL showed the time and reproductive phase dependent effects on the pineal gland and the ovary of this nocturnal bird.     

甘珀酸对内脏痛大鼠延髓星形胶质细胞和神经元反应的影响

目的:研究侧脑室注射甘珀酸后对福尔马林灌胃致内脏疼痛大鼠的延髓迷走孤束复合体内星形胶质细胞和神经元反应的影响.方法:经侧脑室注射缝隙连接阻断剂甘珀酸(carbenoxolone,CBX)后向大鼠胃内灌入2.5%福尔马林2ml诱发内脏疼痛,用免疫组织化学方法观察延髓迷走孤束复合体(VSC)内抗Fos蛋白(标记神经元)和抗胶质原纤维酸性蛋白(标记星形胶质细胞)的单一或双重标记的免疫荧光染色.结果:福尔马林灌胃后大鼠出现烦躁易激惹,呼吸变快,持续1h;而预先侧脑室注射CBX则动物疼痛行为学反应明显减轻.免疫组织化学染色发现福尔马林灌胃后大鼠VSC中的Fos免疫反应数目增强;大鼠预先侧脑室注射CBX后VSC中的Fos免疫反应数目明显减弱.结论:延髓VSC中的星形胶质细胞和神经元参与福尔马林灌胃致内脏痛的调节,星形胶质细胞可能通过缝隙连接影响神经元对内脏痛的调节功能.     

Effect of electrical stimulation of the olfactory tract and the caudal spinal cord on the Dahlgren cells in Clarias batrachus L.

Electrical stimuli applied to the olfactory tract for one minute caused partial depletion, but for two to five minutes resulted in complete depletion of the neurosecretory material (NSM) from the Dahlgren cells as well as from the urophysis. However, if similar stimuli were directly applied to the caudal spinal cord for one minute, the NSM was completely depleted. The neurosecretory granules were reaccumulated in the neurons within fifteen minutes after the stimuli were cut of A rapid depletion of the NSM from the caudal neurons was correlated with their electrical properties and rapid transduction of nervous information into the hormonal message. The immediate response of the caudal neurons to the olfactory tract stimulation suggested that the former are synaptically controlled by a center in the brain.     

Alcohol inhibition of formalin induced depletion of neurosecretory material in the teleost Clarias batrachus (L).

In the normal C. batrachus a fair amount of stainable neurosecretory material (NSM) is always present in all the component parts of the hypothalamo-neurohypophysial (HN) complex. When formalin was injected intraperitoneally 70 to 90% of the NSM was depleted from the HN complex. When ethyl alcohol was administered immediately after formalin treatment, the depletion of NSM was inhibited, and their staining intensity could be compared with those of untreated controls.     

杏仁内侧核注射AVP和AVPMcAb对家兔ET性发热效应的影响

目的和方法：在大脑杏仁内侧核微量注射精氨酸加压素（ＡＶＰ）和精氨酸加压素单克隆抗体（ＡＶＰＭｃＡｂ）,观察其对家兔内毒素（ＥＴ）性发热效应以及视前区一下丘脑前部（ＰＯＡＨ）温敏神经元放电活动的影响。结果：①杏仁内侧核微量注射ＡＶＰ能明显抑制家兔ＥＴ性发热效应,注射ＡＶＰＭｃＡｂ能明显易化家兔ＥＴ性发热效应;②杏仁外侧核分别注射ＡＶＰ和ＡＶＰＭｃＡｂ则对家兔ＥＴ性发热效应无明显影响;③杏仁内侧核分别注射ＡＶＰ和ＡＶＰＭｃＡｂ后ＰＯＡＨ热敏神经元和冷敏神经元放电活动均无明显变化。结论：家兔杏仁内侧核也是ＡＶＰ抗热效应的一个重要的作用部位,杏仁内侧核注射ＡＶＰ的抗热作用途径与隔区注射ＡＶＰ的抗热途径可能不同     

Opioid modulation of thyrotropin releasing hormone induced prolactin secretion

It is known that opioids stimulate prolactin (PRL) secretion by an action on hypothalamic neurons, but in vitro studies have suggested a direct action on the lactotrophs. The present study was performed on male rats known to have little or no PRL response to TRH. A beta-endorphin (beta EP) injection in the third ventricle stimulated PRL secretion and induced furthermore a PRL secretory reaction to TRH injected intravenously 20 min later. Pretreatment with naloxone 10 min before beta EP injection abolished not only the PRL response to beta EP but also the conjugated effect of beta EP and TRH. Pretreatment with naloxone methyl bromide (Br-naloxone), a quaternary naloxone derivative, which does not cross the blood-brain barrier, had no effect on the PRL response to beta EP but prevented the conjugated effect of beta EP and TRH on PRL secretion. Pretreatment of the animals with -methyl-parathyrosine resulting in a dopamine depletion or with haloperidol, a dopamine antagonist, could not induce lactotroph responsiveness to TRH. These results suggest that beta EP in male rat sensitizes the PRL cell to TRH by a direct effect and not through an inhibition of the dopaminergic tone.     

The response of the anterior pituitary and testes to synthetic luteinizing hormone-releasing hormone (LHRH) and the effect of castration on pituitary responsiveness in the maturing chicken fed aflatoxin

The responsiveness of the anterior pituitary to exogenous luteinizing hormone-releasing hormone (LHRH; 20 micrograms/kg body weight) and the subsequent stimulation of testosterone secretion by the testes was studied after administration of dietary aflatoxin (10 ppm) to 9-wk-old male chickens. In both control and aflatoxin-treated males, there were significant (p less than 0.05) increases in plasma luteinizing hormone (LH) concentrations following LHRH administration, which peaked at 5 min post injection and declined thereafter. Plasma testosterone levels increased soon after the LHRH injection in control males, secondary to elevated LH levels in the peripheral circulation, and continued to increase throughout the experimental period. In contrast, this LH-induced elevation in plasma testosterone was delayed in aflatoxin-treated males, with no substantial increase until 20 min post-LHRH injection. In a subsequent experiment, castration of aflatoxin-fed males resulted in an altered response to exogenous LHRH, as compared to their intact counterparts. Based on these data, it appeared that while the LH-secretory capacity of the anterior pituitary was not diminished in birds receiving aflatoxin, the testicular response to exogenous LHRH was altered during aflatoxicosis. Additionally, the effect of castration on plasma LH profiles after LHRH administration provides preliminary evidence for extra-testicular effects of dietary aflatoxin on reproduction in the avian male.     

Attenuation of negatively regulated ANP secretion by calcium in hypertrophied atria

Abnormal intracellular Ca(2+)-handling has been described in various heart diseases associated with cardiac hypertrophy. The crucial role of Ca(2+) in the excitation-secretion coupling in atrial cardiomyocytes is not well established. To investigate modulation of atrial natriuretic peptide (ANP) secretion regulated by Ca(2+) in hypertrophied atria, responsiveness of stretch-induced ANP to Ca(2+) was studied using isolated perfused quiescent hypertrophied rat atria. Male Sprague-Dawley rats were given a single subcutaneous injection of 50 mg/kg monocrotaline (MCT) and were sacrificed at 5-6 weeks. In isolated perfused hypertrophied right atria from MCT rats, changes in atrial volume induced by increased atrial pressure caused proportional increases in mechanically stimulated extracellular fluid (ECF) translocation and stretch-induced ANP secretion. Stretch-induced ANP secretion was markedly increased by the depletion of extracellular Ca(2+). However, an accentuation of stretch-induced ANP secretion by Ca(2+) depletion was markedly attenuated in hypertrophied right atria, as compared to control right atria. Therefore, stretch-induced ANP secretion in terms of ECF translocation by Ca(2+) depletion in hypertrophied atria was significantly lower than in control right atria. However, no significant differences were observed between nonhypertrophied and control left atria. Depletion of extracellular Ca(2+) caused a decrease in intracellular calcium in single beating atrial myocytes, which was significantly attenuated in hypertrophied atrial myocytes. The results suggest that attenuation of Ca(2+)-induced negative regulation of ANP secretion in hypertrophied atria may be due to the disturbance of intracellular Ca(2+) regulation.     

Central somatostatinergic regulation of growth hormone secretion in dwarf chickens.

1. Basal circulating growth hormone (GH) concentrations in sex-linked-dwarf (SLD) chickens were unaffected by the intracerebroventricular (icv) injection of 10, 50 or 100 micrograms somatostatin (SRIF). 2. The GH response to systemic thyrotropin-releasing hormone (TRH; 10 micrograms/kg, iv) was, however, 'paradoxically' enhanced 20 min after icv SRIF administration. 3. A lower dose (1.0 micrograms) of SRIF had no effect on basal or TRH-induced GH release. 4. High-titre SRIF antisera (4 microliters) also had no acute effect on basal plasma GH concentrations, but augmented the GH response to TRH challenge. 5. SRIF would appear to act at central sites to modulate stimulated GH secretion in SLD chickens.     

Menopause and the human hypothalamus: evidence for the role of kisspeptin/neurokinin B neurons in the regulation of estrogen negative feedback

Menopause is characterized by depletion of ovarian follicles, a reduction of ovarian hormones to castrate levels and elevated levels of serum gonadotropins. Rather than degenerating, the reproductive neuroendocrine axis in postmenopausal women is intact and responds robustly to the removal of ovarian hormones. Studies in both human and non-human primates provide evidence that the gonadotropin hypersecretion in postmenopausal women is secondary to increased gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus. In addition, menopause is accompanied by hypertrophy of neurons in the infundibular (arcuate) nucleus expressing KiSS-1, neurokinin B (NKB), substance P, dynorphin and estrogen receptor alpha (ERalpha) mRNA. Ovariectomy in experimental animals induces nearly identical findings, providing evidence that these changes are a compensatory response to ovarian failure. The anatomical site of the hypertrophied neurons, as well as the extensive data implicating kisspeptin, NKB and dynorphin in the regulation of GnRH secretion, provide compelling evidence that these neurons are part of the neural network responsible for the increased levels of serum gonadotropins in postmenopausal women. We propose that neurons expressing KiSS-1, NKB, substance P, dynorphin and ERalpha mRNA in the infundibular nucleus play an important role in sex-steroid feedback on gonadotropin secretion in the human.     

A reproductive phase-dependent effect of dietary L-tryptophan on pineal gland and gonad of a nocturnal bird, Indian spotted owlet Athene brama

Unlike other temperate owls, Indian spotted owlet Athene brama possesses a well-developed pineal gland that secrets moderate amount of hydroxy- (serotonin) and methoxy- (melatonin) indoles in circulation. However, in this study, we have reported the response of this endocrine gland to exogenous L-Tryptophan (precursor of the above indoles), and also its effect on gonads of this nocturnal bird. During breeding phase or pineal inactive phase (March), oral treatment of L-Trp (0.5 mg/100 g Bwt/day) significantly increased the pineal gland wt and plasma melatonin (MEL) level, while decreased the gonadal wt and plasma sex steroids levels (estradiol and progesterone in female and testosterone in male). Interestingly, during reproductively quiescent phase or pineal active phase (August), similar amount of L-Trp significantly decreased the plasma MEL level, while increased the above sex steroid levels in plasma. Finally, the results show a clear reproductive phase-dependent inverse effect of L-Trp on pineal gland and gonads for both sexes of the spotted owlets, and suggest that the therapeutic use of this amino acid would be a great advantage for controlling the reproduction of these economically important birds.     

Circadian Rhythms of Melatonin and Sex Steroids in a Nocturnal Bird, Indian Spotted Owlet Athene brama During Reproductively Active and Inactive Phases

The epiphyseal neurohormone melatonin (MEL) exhibits circadian cyclicity, as noted extensively in diurnal vertebrates although very little information is available regarding nocturnal species. We have studied the MEL rhythmicity with 24-hour periodicity in a tropical nocturnal bird, Indian spotted owlet Athene brama, which possesses a well-developed pineal organ. We performed our study during two crucial reproductive phases (active and inactive), when the pineal gland activity in owlet exists in inverse states, i.e., inactive and active respectively. Independent of sex, the circadian rhythm of plasma MEL in owlets showed a two-peak cyclicity with a smaller peak at around 1400 h and the higher one at about 0200 h, while the lowest value was found at 1000 h. The night (0200 h) peak activity of plasma MEL in owlet has a resemblance with the earlier findings in diurnal birds and strongly suggests that independent of species habit the peak activity of MEL is invariably dark dependent. However, the daytime peak of MEL may be due to the daytime hiding nature of this nocturnal bird. Interestingly, it was also noted that the hours of peak activity of MEL (1400 and 0200 h) were the same during both of the reproductive phases, though the environmental day length was longer and ambient temperature was higher during the reproductively inactive phase. During daytime these birds hide in a dark burrow where, in general, the intensities of light and temperature are less, and the amplitude of variations of these factors is not prominent. Hence, the seasonal variations in these oscillatory components may not have affected the entrainment of the owlet pineal oscillator, which regulates the daily MEL rhythm in a similar pattern during both the studied phases. On the other hand, a single circadian peak (around 1000 h) circadian cyclicity of gonadal steroids (i.e., testosterone in the male and estradiol and progesterone in the female) showed an inverse relationship with plasma MEL. Possibly, MEL regulates the daily steroidogenic status in owlets by an inhibitory influence.     

Hypotensive hypovolemia and hypoglycemia activate different hindbrain catecholamine neurons with projections to the hypothalamus

To better understand the involvement of hindbrain catecholamine neurons in hypovolemia-induced secretion of AVP, we injected antidopamine beta-hydroxylase saporin (DSAP) or unconjugated saporin (SAP) control solution into the hypothalamic paraventricular nucleus (PVH) of anesthetized rats to retrogradely lesion catecholamine neurons innervating magnocellular areas of the hypothalamus. Subsequently, hypotensive hypovolemia was induced by remote blood withdrawal (4.5 ml, 1 ml/min) using an intra-atrial catheter. Blood was sampled at 2, 5, 20, and 50 min after onset of blood withdrawal. The AVP response was severely impaired by DSAP. Peak responses at 50 min were 51 pg/ml in SAP control and 17 pg/ml in DSAP-lesioned rats, indicating the importance of catecholamine neurons for this response. We also measured AVP responses to osmotic challenge induced by administration of hypertonic saline (1 M, 15 ml/kg, sc) and to insulin-induced hypoglycemia. Osmotic challenge increased AVP levels, but the response was not impaired by DSAP, indicating that AVP neurons were not damaged by the DSAP injection. Insulin-induced hypoglycemia did not increase AVP levels in either DSAP- or SAP-treated rats. However, the same dose of insulin increased food intake and corticosterone secretion in SAP controls, and these responses were profoundly impaired by DSAP. Thus catecholamine neurons are required for both the AVP response to hypotensive hypovolemia and for feeding and corticosterone responses to hypoglycemia. Lack of an AVP response to insulin-induced hypoglycemia in intact rats therefore indicates that responses to hypovolemia and hypoglycemia are mediated by different catecholamine neurons under distinct sensory controls.     

Circadian Rhythms of Melatonin and Sex Steroids in a Nocturnal Bird,Indian Spotted Owlet Athene brama During Reproductively Active and Inactive Phases

The epiphyseal neurohormone melatonin (MEL) exhibits circadian cyclicity, as noted extensively in diurnal vertebrates although very little information is available regarding nocturnal species. We have studied the MEL rhythmicity with 24-hour periodicity in a tropical nocturnal bird, Indian spotted owlet Athene brama, which possesses a well-developed pineal organ. We performed our study during two crucial reproductive phases (active and inactive), when the pineal gland activity in owlet exists in inverse states, i.e., inactive and active respectively. Independent of sex, the circadian rhythm of plasma MEL in owlets showed a two-peak cyclicity with a smaller peak at around 1400 h and the higher one at about 0200 h, while the lowest value was found at 1000 h. The night (0200 h) peak activity of plasma MEL in owlet has a resemblance with the earlier findings in diurnal birds and strongly suggests that independent of species habit the peak activity of MEL is invariably dark dependent. However, the daytime peak of MEL may be due to the daytime hiding nature of this nocturnal bird. Interestingly, it was also noted that the hours of peak activity of MEL (1400 and 0200 h) were the same during both of the reproductive phases, though the environmental day length was longer and ambient temperature was higher during the reproductively inactive phase. During daytime these birds hide in a dark burrow where, in general, the intensities of light and temperature are less, and the amplitude of variations of these factors is not prominent. Hence, the seasonal variations in these oscillatory components may not have affected the entrainment of the owlet pineal oscillator, which regulates the daily MEL rhythm in a similar pattern during both the studied phases. On the other hand, a single circadian peak (around 1000 h) circadian cyclicity of gonadal steroids (i.e., testosterone in the male and estradiol and progesterone in the female) showed an inverse relationship with plasma MEL. Possibly, MEL regulates the daily steroidogenic status in owlets by an inhibitory influence.     

鞘内注射MK-801对炎性痛大鼠海马NOS表达及NO含量的影响

目的：观察鞘内给予N-甲基-D-天门冬氨酸（NMDA）受体拮抗剂MK-801对足底注射甲醛诱导的自发痛反应和海马一氧化氮合酶（NOS）表达及一氧化氮（N0）含量的影响,探讨炎性痛诱导海马NO产生增多的机制。方法：通过观察舔足反射时间反映大鼠自发痛程度;采用NADPH—d组织化学法测定大鼠海马NOS表达;硝酸还原酶法测定海马组织NO含量。结果：足底注射甲醛后动物即出现舔、咬、摇动注射侧脚掌等自发痛相关表现,预先鞘内注射MK-801可使大鼠第二时相自发病程度显著降低,但对第一时相痛反应程度无明显影响。注射甲醛后12h时,海马CA1、CA2～3区及DG区NOS阳性细胞数目、阳性细胞染色深度均显著增加,海马组织NO含量显著增加;预先鞘内注射MK-801,可使甲醛炎性痛大鼠海马各区NOS阳性细胞数目明显减少,阳性细胞染色深度明显变浅,海马NO含量明显降低。结论：鞘内注射MK-801可逆转甲醛炎性痛诱导的海马NOS表达及NO产生的增加,表明甲醛炎性痛诱导的海马NO产生增加主要是由于伤害性信息传入所引起。     

The hypothalamic neuropeptide oxytocin is required for formation of the neurovascular interface of the pituitary

The hypothalamo-neurohypophyseal system (HNS) is?the neurovascular structure through which the hypothalamic neuropeptides oxytocin and arginine-vasopressin exit the brain into the bloodstream, where they go on to affect peripheral physiology. Here, we investigate the molecular cues that regulate the neurovascular contact between hypothalamic axons and neurohypophyseal capillaries of the zebrafish. We developed a transgenic system in which both hypothalamic axons and neurohypophyseal vasculature can be analyzed in?vivo. We identified the cellular organization of the zebrafish HNS as well as the dynamic processes that contribute to formation of the HNS neurovascular interface. We show that formation of this interface is regulated during development by local release of oxytocin, which affects endothelial morphogenesis. This cell communication process is essential for the establishment of a tight axovasal interface between the neurons and blood vessels of the HNS. We present a unique example of axons affecting endothelial morphogenesis through secretion of a neuropeptide.     

外周P物质受体介导伤害性刺激所致脊髓背角c-fos基因的表达

用免疫组化染色方法,观察了Ｐ物质受体在外周对伤害性刺激信息的介导作用。于福尔马林注入双侧后肢足底前１０ｍｉｎ,将不同浓度的ＳＰ受体特异性拮抗剂Ｌ６６８,１６９注入一侧足底,另一侧注入生理盐水。结果：１０＾－４ｍｏｌ／Ｌ的Ｌ６６８,１６９明显抑制了该侧脊髓背角浅层ｃ－ｆｏｓ基因的表达而对深层影响不大;