The emetic activity of staphylococcal enterotoxins,SEK, SEL,SEM, SEN and SEO in a small emetic animal model,the house musk shrew

Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus are the most recognizable causative agents of emetic food poisoning in humans. New types of SEs and SE‐like (SEl) toxins have been reported. Several epidemiological investigations have shown that the SEs and SEl genes, particularly, SEK, SEL, SEM, SEN and SEO genes, are frequently detected in strains isolated from patients with food poisoning. The purpose of the present study was to evaluate the emetic activity of recently identified SEs using a small emetic animal model, the house musk shrew. The emetic activity of these SEs in house musk shrews was evaluated by intraperitoneal administration and emetic responses, including the number of shrews that vomited, emetic frequency and latency of vomiting were documented. It was found that SEs induce emetic responses in these animals. This is the first time to demonstrate that SEK, SEL, SEM, SEN and SEO possess emetic activity in the house musk shrew.     

Immunohistochemical demonstration of c-fos protein in neurons of the medulla oblongata of the musk shrew (Suncus murinus) after veratrine administration.

We subcutaneously injected 0.5 mg/kg veratrine into the musk shrew (Suncus murinus), observed the presence or absence, latency, and the incidence of vomiting in each animal for 90 min, and selected animals that frequently vomited (FV group) and those that did not vomit (NV group). Subsequently, animal brains were removed, and the induction of c-fos protein (Fos) was immunohistochemically examined to evaluate neuronal activity in the medulla oblongata. The distribution of Fos-positive neurons in the medulla oblongata was similar between FV and NV groups, with numerous neurons along the entire length of the nucleus of the solitary tract and in the ventrolateral reticular formation. Both veratrine-injected groups showed higher numbers of positive neurons than the saline administered group. However, while the FV group showed a high concentration of positive neurons in the dorsal-dorsomedial reticular formation of the nucleus ambiguus in the rostral medulla, the NV group showed few positive neurons in this area. Fos activity in neurons in this area appeared to be higher in animals with a higher incidence of vomiting.     

Why Can’t Rodents Vomit? A Comparative Behavioral,Anatomical, and Physiological Study

The vomiting (emetic) reflex is documented in numerous mammalian species, including primates and carnivores, yet laboratory rats and mice appear to lack this response. It is unclear whether these rodents do not vomit because of anatomical constraints (e.g., a relatively long abdominal esophagus) or lack of key neural circuits. Moreover, it is unknown whether laboratory rodents are representative of Rodentia with regards to this reflex. Here we conducted behavioral testing of members of all three major groups of Rodentia; mouse-related (rat, mouse, vole, beaver), Ctenohystrica (guinea pig, nutria), and squirrel-related (mountain beaver) species. Prototypical emetic agents, apomorphine (sc), veratrine (sc), and copper sulfate (ig), failed to produce either retching or vomiting in these species (although other behavioral effects, e.g., locomotion, were noted). These rodents also had anatomical constraints, which could limit the efficiency of vomiting should it be attempted, including reduced muscularity of the diaphragm and stomach geometry that is not well structured for moving contents towards the esophagus compared to species that can vomit (cat, ferret, and musk shrew). Lastly, an in situ brainstem preparation was used to make sensitive measures of mouth, esophagus, and shoulder muscular movements, and phrenic nerve activity–key features of emetic episodes. Laboratory mice and rats failed to display any of the common coordinated actions of these indices after typical emetic stimulation (resiniferatoxin and vagal afferent stimulation) compared to musk shrews. Overall the results suggest that the inability to vomit is a general property of Rodentia and that an absent brainstem neurological component is the most likely cause. The implications of these findings for the utility of rodents as models in the area of emesis research are discussed.     

Comparative studies of the dorsal surface of the tongue in three mammalian species by scanning electron microscopy

Comparative features of the dorsal tongue epithelia in musk shrews, mongooses and rats were described. The shapes of the filiform papillae were different in each of the species. The distribution pattern of filiform papillae was similar both in the musk shrews and mongoose, in that the form of filiform papillae changed gradually from the lingual apex to the posterior part of the lingual body. By contrast, the different types of filiform papillae were distributed on definite areas of the dorsal lingual surface in the rat. Microridges on the interpapillar surface in the musk shrew and mongoose presented a clear outline, but those of the rat were not so distinct. In all species, the upper surface of filiform papillae did not show any distinct microridges.     

The inhibitory effect of halothane on the emetic response in the ferret

Emesis and nausea are often associated with anaesthesia and continue to be a common clinical problem. Past clinical studies have demonstrated that halothane produces a higher incidence of vomiting compared with other anaesthetics, but some investigators have described an antiemetic effect. The purpose of this study was to investigate the effects of various doses of halothane on the emetic response in the decerebrate ferret. Following a control emetic response, a maximum of six increasing cumulative concentrations of halothane were delivered. At the end of each delivery period, the supradiaphragmatic vagal communicating branch, which has been shown to reproducibly elicit vomiting, was electrically stimulated and the emetic response was monitored. An increase in halothane concentration produced a marked depression of tongue, abdominal muscle, and diaphragm EMG activity as well as a decrease in central venous pressure. Licking, a prodromal response comparable to nausea in the human, appeared to be most sensitive. An increase in latency of the emetic response occurred as the concentration of halothane was increased. All phases of the response were observed at concentrations below 0.6 vol% halothane. At 0.6 vol% halothane, 75% of the animals vomited. At higher concentrations, the emetic response was completely abolished. One hour post-halothane, all latencies had returned to near control values. The methods utilized in this study provided a model that was not complicated by a large number of variables usually present in clinical studies. These data demonstrate that halothane exerts an inhibitory, concentration-dependent, and reversible effect on the emetic response in the ferret and provide further support that halothane alone does not possess emetic properties at clinical properties at clinical concentrations.     

Characterization of radiation-induced emesis in the ferret

Forty-eight ferrets (Mustela putorius furo) were individually head-shielded and radiated with bilateral 60Co gamma radiation at 100 cGy min-1 at doses ranging between 49 and 601 cGy. The emetic threshold was observed at 69 cGy, the ED50 was calculated at 77 cGy, and 100% incidence of emesis occurred at 201 cGy. With increasing doses of radiation, the latency to first emesis after radiation decreased dramatically, whereas the duration of the prodromal period increased. Two other sets of experiments suggest that dopaminergic mechanisms play a minor role in radiation-induced emesis in the ferret. Twenty-two animals were injected either intravenously or subcutaneously with 30 to 300 micrograms/kg of apomorphine. Fewer than 50% of the animals vomited to 300 micrograms/kg apomorphine; central dopaminergic receptor activation was apparent at all doses. Another eight animals received 1 mg/kg domperidone prior to either 201 (n = 4) or 401 (n = 4) cGy radiation and their emetic responses were compared with NaCl-injected-irradiated controls (n = 8). At 201 cGy, domperidone significantly reduced only the total time in emetic behavior. At 401 cGy, domperidone had no salutary effect on radiation-induced emesis. The emetic responses of the ferret to radiation and apomorphine are compared with these responses in other vomiting species.     

An attempt at reciprocal crosses between laboratory strains of large and small musk shrews (Suncus murinus)--influence of body-weight difference between sexes on mating success

We conducted mating experiments between two laboratory strains of musk shrews (Suncus murinus), the large-sized shrews (BAN strain) originating from Bangladesh and the small-sized animals (NAG strain) from Nagasaki, Japan. In the 16 mating trials between 12 BAN females (mean body weight of 87.9 g) and 11 NAG males (52.3 g), highly aggressive fighting behaviors of the BAN females toward the NAG males were observed. The BAN females stayed in nest boxes in cages, whereas the NAG males kept out during the mating trials. No pregnant females were found in the trials. Their pregnancies were diagnosed by palpation on the day about 16 days after the separation of the pairs. Contrastively, in 6 of the 11 trials between 8 NAG females (34.2 g) and 6 BAN males (145.9 g), the viable and fertile F1 hybrids of 8 females and 8 males were produced. The F1, subsequent F2 and backcross progenies appeared neither external nor behavioral abnormalities. Various types of crosses using the F1, F2, and the two parental shrews showed that mating success was in a condition that females were nearly as heavy as males, or lighter. Although body weights of musk shrews from different geographical areas were reported to vary from 43.5 to 147.3 g in males and from 26.0 to 82.0 g in females, males in respective localities were constantly about 1.7 times heavier than the corresponding females. These results therefore suggest that body-weight differences between sexes paired greatly affect mating success in the cross between the strains of induced ovulatory shrews.     

The emetic reflex in African walking catfish develops with age

This opportunistic observational study showed that following feeding, subadult catfish, Clorias gariepinus (>3 months old; n=37) were sensitive to the disturbance caused by removing two fish for weighing. This initiated intense and prolonged vomiting (oral expulsion of upper gut contents). The main emetic response occurred within a few minutes after fish removal, although commercial grade food pellets were still being vomited 50 to 100 min later. The magnitude of the vomiting response was relatively greater after consumption of larger meals, however, nothan 44% of a meal was ever vomited. Juvenile catfish (<3 months; n=8) were also sensitive to disturbance as indicated by vomiting. The emetic response in these younger fish wasas pronounced as that of the subadults even when given meals of similar relative size (approx. 2.4% wet body weight). No emesis was observed in post-hatching catfish (<3 weeksd; n=7) after feeding and following a similar disturbance. This suggests the emetic reflex may not operate in post-hatching catfish in reaction to a stimulus that in subadults and juveniles produced a graded, weight-dependent vomiting response. This raises the question of whether this difference represents neuronal pathway development or learning of the reflex.     

Inhibition of emetic and superantigenic activities of staphylococcal enterotoxin A by synthetic peptides

Staphylococcus aureus is a major human pathogen producing different types of toxins. Enterotoxin A (SEA) is the most common type among clinical and food-related strains. The aim of the present study was to estimate functional regions of SEA that are responsible for emetic and superantigenic activities using synthetic peptides. A series of 13 synthetic peptides corresponding to specific regions of SEA were synthesized, and the effect of these peptides on superantigenic activity of SEA including interferon γ (IFN-γ) production in mouse spleen cells, SEA-induced lethal shock in mice, spleen cell proliferation in house musk shrew, and emetic activity in shrews were assessed. Pre-treatment of spleen cells with synthetic peptides corresponding to the regions 21–40, 35–50, 81–100, or 161–180 of SEA significantly inhibited SEA-induced IFN-γ production and cell proliferation. These peptides also inhibited SEA-induced lethal shock. Interestingly, peptides corresponding to regions 21–40, 35–50 and 81–100 significantly inhibited SEA-induced emesis in house musk shrews, but region 161–180 did not. These findings indicated that regions 21–50 and 81–100 of SEA are important for both superantigenic and emetic activities of SEA molecule while region 161–180 is involved in superantigenic activity but not emetic activity of SEA. These regions could be important targets for therapeutic intervention against SEA exposure.     

NADPH-Diaphorase-containing neurons in the medullary structures involved in generation of the respiratory activity in neonatal rats

Using a histochemical technique, we examined distribution of the neurons containing a marker of nitric oxide synthase (NOS), NADPH-diaphorase (NADPH-d), on frontal slices of the medulla and upper cervical spinal segments of 4-day-old rats. It was demonstrated that NADPH-d-positive cells are present within the dorsal and ventral medullary respiratory groups. The highest density of the labeled middle-size multipolar neurons (27.9±2.6 cells per 0.1 mm² of the slice) was observed in the rostral part of the ventral respiratory group, within the reticular lateral paragigantocellular nucleus. Similar NADPH-d-positive neurons were also observed in other reticular formation structures: rostroventrolateral reticular, gigantocellular, and ventral medullary nuclei, and in the ventral part of the paramedial nucleus. There were no labeled neurons in the lateral reticular nucleus. Single small and medium-size labeled neurons were found at all rostro-caudal levels of thenucl. ambiguous (nuclei retrofacialis, ambiguous, andretroam-biguous). Groups of NADPH-d-positive neurons were also revealed within the dorsal respiratory group, along the whole length of thenucl. tractus solitarii (mostly in its ventrolateral parts). Single labeled neurons were also observed in thenucl. n. hypoglossi, and their groups were observed in the dorsal motor part of thenucl. n. vagus. Involvement of the structures containing NADPH-d-positive neurons in the processes related to generation of the respiratory activity is discussed. Our neuroanatomical experiments prove that in early postnatal mammals NO is actively involved in generation and regulation of the medullary respiratory rhythm. Neirofiziologiya/Neurophysiology, Vol. 32, No. 2, pp. 128–136, March–April, 2000.     

Emesis, radiation exposure, and local cerebral blood flow in the ferret

We examined the sensitivity of the ferret to emetic stimuli and the effect of radiation exposure near the time of emesis on local cerebral blood flow. Ferrets vomited following the administration of either apomorphine (approx 45% of the ferrets tested) or peptide YY (approx 36% of those tested). Exposure to radiation was a very potent emetic stimulus, but vomiting could be prevented by restraint of the hindquarters of the ferret. Local cerebral blood flow was measured using a quantitative autoradiographic technique and with the exception of several regions in the telencephalon and cerebellum, local cerebral blood flow in the ferret was similar to that in the rat. In animals with whole-body exposure to moderate levels of radiation (4 Gy of 137Cs), mean arterial blood pressure was similar to that in the control group. However, 15-25 min following irradiation there was a general reduction of local cerebral blood flow ranging from 7 to 33% of that in control animals. These cerebral blood flow changes likely correspond to a reduced activation of the central nervous system.     

Nociceptive afferents to the premotor neurons that send axons simultaneously to the facial and hypoglossal motoneurons by means of axon collaterals

It is well known that the brainstem premotor neurons of the facial nucleus and hypoglossal nucleus coordinate orofacial nociceptive reflex (ONR) responses. However, whether the brainstem PNs receive the nociceptive projection directly from the caudal spinal trigeminal nucleus is still kept unclear. Our present study focuses on the distribution of premotor neurons in the ONR pathways of rats and the collateral projection of the premotor neurons which are involved in the brainstem local pathways of the orofacial nociceptive reflexes of rat. Retrograde tracer Fluoro-gold (FG) or FG/tetramethylrhodamine-dextran amine (TMR-DA) were injected into the VII or/and XII, and anterograde tracer biotinylated dextran amine (BDA) was injected into the caudal spinal trigeminal nucleus (Vc). The tracing studies indicated that FG-labeled neurons receiving BDA-labeled fibers from the Vc were mainly distributed bilaterally in the parvicellular reticular formation (PCRt), dorsal and ventral medullary reticular formation (MdD, MdV), supratrigeminal nucleus (Vsup) and parabrachial nucleus (PBN) with an ipsilateral dominance. Some FG/TMR-DA double-labeled premotor neurons, which were observed bilaterally in the PCRt, MdD, dorsal part of the MdV, peri-motor nucleus regions, contacted with BDA-labeled axonal terminals and expressed c-fos protein-like immunoreactivity which induced by subcutaneous injection of formalin into the lip. After retrograde tracer wheat germ agglutinated horseradish peroxidase (WGA-HRP) was injected into VII or XII and BDA into Vc, electron microscopic study revealed that some BDA-labeled axonal terminals made mainly asymmetric synapses on the dendritic and somatic profiles of WGA-HRP-labeled premotor neurons. These data indicate that some premotor neurons could integrate the orofacial nociceptive input from the Vc and transfer these signals simultaneously to different brainstem motonuclei by axonal collaterals.     

Postnatal growth pattern of F1 hybrids of a cross between two strains of large and small musk shrews, Suncus murinus

In our previous comparison of the postnatal growth of two laboratory strains of the musk shrew (Suncus murinus), the large shrews originating in Bangladesh (BAN strain) and the small shrews from Nagasaki, Japan (NAG strain), we found that differences in the 120-day adult body weight of the two strains (BAN: males 135.3g and females 82.0g; NAG: 52.9 and 34.2g, respectively) reflect both an approximately 2.5 times longer linear growth phase and an approximately 1.5 times higher growth rate during this phase in the BAN strain. We examined the postnatal growth (from 5 to 120 days after birth) of the F1 hybrids of a cross between the two strains and compared our findings with the above-mentioned growth data for the parent strains. A growth equation composed of linear and monomolecular functions was fitted to the growth data for the shrews. The growth trajectories of both sexes of the F1 hybrids were situated roughly midway between those of the two parent strains throughout the entire growth process. The adult body weight of the F1 shrews at 120 days of age averaged 86.0g in the males and 51.7g in the females. The growth phase lasted approximately 60 days in the males and approximately 40 days in the females of both the F1 shrews and the parent strains. The duration of the linear growth phase of the F1 hybrids (29.8 days in the males and 19.0 days in the females), however, was approximately intermediate between the parent strains (BAN: males 33.4 days and females 26.1 days; NAG: 18.8 and 13.9 days, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Somatostatin-immunoreactive senile plaque-like structures in the frontal cortex and nucleus accumbens of aged tree shrews and Japanese macaques

BACKGROUND: Previously, we demonstrated decreased expression of somatostatin mRNA in aged macaque brain, particularly in the prefrontal cortex. To investigate whether or not this age-dependent decrease in mRNA is related to morphological changes, we analyzed somatostatin cells in the cerebra of aged Japanese macaques and compared them with those in rats and tree shrews, the latter of which are closely related to primates. Methods: Brains of aged macaques, tree shrews, and rats were investigated by immunohistochemistry with special emphasis on somatostatin. Results: We observed degenerating somatostatin-immunoreactive cells in the cortices of aged macaques and tree shrews. Somatostatin-immunoreactive senile plaque-like structures were found in areas 6 and 8 and in the nucleus accumbens of macaques, as well as in the nucleus accumbens and the cortex of aged tree shrews, where amyloid accumulations were observed. CONCLUSIONS: Somatostatin degenerations may be related to amyloid accumulations and may play roles in impairments of cognitive functions during aging.     

Cardiac effects of hypocretin-1 in nucleus ambiguus

Although recent studies have reported hypocretin 1 (hcrt-1)-like-immunoreactivity (ir) within the region of the nucleus ambiguus (Amb) in the caudal brain stem, the function of hcrt-1 in the Amb on cardiovascular function is not known. Three series of experiments were done in male Wistar rats to investigate the effects of microinjections of hcrt-1 into Amb on heart rate (HR), mean arterial pressure (MAP), and the arterial baroreceptor reflex. In the first series, a detailed mapping of the distribution of hcrt-1- and hcrt-1 receptor (hcrtR-1)-like-ir was obtained of the Amb region. Although hcrt-1-like- and hcrtR-1-like-ir were found throughout the rostrocaudal extent of the Amb and adjacent ventrolateral medullary reticular formation, most of the hcrtR-1-like-ir was observed in the area just ventral to the compact formation of Amb, in the region of the external formation of the nucleus (Ambe). In the second series, the Amb region that contained hcrt-1 and hcrtR-1-ir was explored for sites that elicited changes in HR and MAP in urethane and alpha-chloralose-anesthetized rats. Microinjections of hcrt-1 (0.5-2.5 pmol) into the Ambe elicited a dose-related decrease in HR, with little or no direct change in MAP. The small decreases in MAP were found to be secondary to the HR changes. The largest bradycardia responses were elicited from sites in the Ambe. Administration (iv) of the muscarinic receptor antagonist atropine methyl bromide or ipsilateral vagotomy abolished the HR response, indicating that the HR response was due to activation of vagal cardiomotor neurons. In the final series, microinjections of hcrt-1 into the Ambe significantly potentiated the reflex bradycardia elicited by activation of the baroreflex as a result of the increased MAP after the intravenous injection of phenylephrine. These data suggest that hcrt-1 in the Ambe activates neuronal systems that alter the excitability of central circuits that reflexly control the circulation through the activation of vagal preganglionic cardioinhibitory neurons.     

Diabetic cataract of the musk shrew (Suncus murinus, Insectivora) exhibiting spontaneous non-insulin dependent diabetes mellitus (NIDDM).

The EDS colony, developed as a new laboratory colony of the musk shrew, is characterized by a high incidence of early-onset spontaneous non-insulin dependent diabetes mellitus (NIDDM). In this colony, a few diabetic shrews exhibited a cataract at 1 month after the onset of diabetes, and all diabetic shrews had bilateral cataracts at 5 months after the onset of diabetes. In contrast, cataractous animals were never observed among non-diabetic shrews. These results suggest that the cataract in the EDS colony is a diabetic complication.     

New data on the immunocytochemical localization of thyrotropin-releasing hormone in the rat central nervous system

An antiserum raised against the synthetic tripeptide pyroglutamyl-histidyl-proline (free acid) was used to localize thyrotropin-releasing hormone (TRH) in the rat central nervous system (CNS) by immunocytochemistry. The distribution of TRH-immunoreactive structures was similar to that reported earlier; i.e., most of the TRH-containing perikarya were located in the parvicellular part of the hypothalamic paraventricular nucleus, the suprachiasmatic portion of the preoptic nucleus, the dorsomedial nucleus, the lateral basal hypothalamus, and the raphe nuclei. Several new locations for TRH-immunoreactive neurons were also observed, including the glomerular layer of the olfactory bulb, the anterior olfactory nuclei, the diagonal band of Broca, the septal nuclei, the sexually dimorphic nucleus of the preoptic area, the reticular thalamic nucleus, the lateral reticular nucleus of the medulla oblongata, and the central gray matter of the mesencephalon. Immunoreactive fibers were seen in the median eminence, the organum vasculosum of the lamina terminalis, the lateral septal nucleus, the medial habenula, the dorsal and ventral parabrachial nuclei, the nucleus of the solitary tract, around the motor nuclei of the cranial nerves, the dorsal vagal complex, and in the reticular formation of the brainstem. In the spinal cord, no immunoreactive perikarya were observed. Immunoreactive processes were present in the lateral funiculus of the white matter and in laminae V-X in the gray matter. Dense terminal-like structures were seen around spinal motor neurons. The distribution of TRH-immunoreactive structures in the CNS suggests that TRH functions both as a neuroendocrine regulator in the hypothalamus and as a neurotransmitter or neuromodulator throughout the CNS.     

The organization of the reptilian brainstem reticular formation: A comparative study using Nissl and Golgi techniques

The brainstem reticular formation has been studied in 16 genera representing 11 families of reptiles. Measurements of Nissl-stained reticular neurons revealed that they are distributed along a continuum, ranging in length from 10 μm to 95 μm. Reticular neurons in crocodilians and snakes tend to be larger than those found in lizards and turtles. Golgi studies revealed that reticular neurons posess long, rectilinear, sparsely branching dendrites. Small reticular neurons ( > 31 μm length) possess fusiform or triangular somata which bear two or three primary dendrites. These dendrites have a somewhat simpler ramification pattern when compared with those of large reticular neurons (< 30 μm length). Large reticular neurons generally possess perikarya which are triangular or polygonal in shape. The somata of large reticular neurons bear an average of four primary dendrites. The dendrites of reptilian reticular neurons ramify predominantly in the transverse plane and are devoid of spines or excrescences. The dendritic ramification patterns observed in the various repitilian reticular nuclei were correlated with known input and output connections of these nuclei. Nissl and Golgi techniques were used to divide the reticular formation into seven nuclei. A nucleus reticularis inferior (RI) is found in the myelencephalon, a reticularis medius (RM) in the caudal two-thirds of the metencephalon, and a reticularis superior (RS) in the rostral metencephalon and caudal mesencephalon. Reticularis inferior can be subdivided into a dorsal portion (RID) and a ventral portion (RIV). All reptilian groups possess RID and RM but RIV is lacking in turtles. Reticularis superior can be subdivided into a large-celled lateral portion (RSL) and a small-celled medial portion (RSM). All reptilian groups possess RSM and RSL, but RSL is quite variable in appearance, being best developed in snakes and crocodilians. The myelencephalic raphe nucleus is also quite variable in its morphology among the different reptilian families. A seventh reticular nucleus, reticularis ventrolateralis (RVL), is found only in snakes and in teiid lizards. It was noted that the reticular formation is simpler (fewer numbers of nuclei) in the representatives of older reptilian lineages and more complex (greater numbers of nuclei) in the more modern lineages. Certain reticular nuclei are present or more extensive in those families which have prominent axial musculature.     

Common system of sparsely branched projection (reticular) NADPH-diaphorase neurons in the human forebrain formations built from densely branched cells

Cell morphometry with statistical analysis (using 9 parameters) of densely branched projection and sparsely branched reticular neurons was performed in the human forebrain formations built from densely branched projection neurons (the entorhinal cortex, striatum, nucleus accumbens basolateral amygdala, and dorsal thalamus). The reticular neurons included scattered reticular neurons and marginal reticular neurons of the dorsal thalamus. Golgi method and staining for NADPH-diaphorase were used. The scattered reticular neurons of different formations under study did not differ in any of the 9 parameters, whereas they significantly differed from the main projection neurons in 5 to 7 parameters (except one comparison with the difference in 2 parameters). Within the same formation, the scattered reticular and main projection densely branched neurons differed in 7 to 9 parameters. The endbrain scattered reticular neurons expressed NADPH-diaphorase, while in the dorsal thalamus only the medium marginal reticular neurons were NADPH-diaphorase-positive. Thus, a common system of ancient integrative reticular neurons expressing NADPH-diaphorase exists in the examined human forebrain formations. The evidence obtained by us and the literature data point to the projection nature of the scattered reticular neurons (to the V and VI neocortical layers), which suggests their modulatory influence on descending neocortical pathways.     

Diurnal rhythm of drinking activity in the house musk shrew]

A diurnal rhythm of drinking activity in 7 male and 6 female house musk shrews (Jic: SUN) aged about one year was observed over a period of 10 days under a schedule of 12 hr light and 12 hr darkness (light on at 07:00). In general, the pattern of drinking activity was similar among both sexes, with around 24-hr diurnal rhythm. A few typical drinking patterns of these animals were represented as follows: 1) Drinking interval was very close in the dark phase, while it was a little too sparse in the light phase (n = 4). 2) Its interval remains stationary through a whole day (n = 5). 3) Drinking was performed between the latter half of light and the first half of dark phases (n = 4).