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PubMed1990

Ultrastructural study of tracer permeability through the cat and ferret enamel organ.

The access of exogenous materials to the developing enamel surface has been intensively studied in rodents, but not in other mammalian species. This ultrastructural study investigates the permeability of injected horseradish peroxidase (HRP) and lanthanum tracers in cat and ferret tooth buds. In cat enamel organs fixed by immersion, lanthanum did not escape the capillaries overlying secretory stage tooth buds, but it did permeate up to the distal junctions of ruffle-ended (RA) and the proximal junctions of smooth-ended (SA) ameloblasts. Perfusion fixation with lanthanum compromised junctional integrity of cat ameloblasts at all stages of development. Similarly, HRP rarely escaped the capillaries associated with cat secretory stage enamel organs. However, unlike lanthanum, HRP was mostly confined to the vasculature of maturation stage enamel organs in immersion fixed cats at all time intervals examined. In ferrets, HRP penetrated up to, but not beyond, the distal junctional complexes of secretory ameloblasts. In maturation stage enamel organs, HRP coated the papillary and RA cells, but did not penetrate the RA distal cell junctions. HRP did permeate the extracellular spaces of SA to reach the underlying enamel surface. Ameloblasts in transitional phases of SA and RA endocytosed HRP at the distal cell surface. This data leads to several conclusions. First, HRP localization in the ferret paralleled that observed in rodents. Second, the results of cat enamel organs substantiate previous studies showing perfusion fixation can increase vascular and intercellular permeability to lanthanum. However, in cats fixed by immersion, both lanthanum and HRP were restricted to capillaries associated with the secretory stage enamel organ, and only lanthanum escaped maturation stage capillaries. It is suggested that variations in the fenestrations and distribution of capillaries associated with the cat enamel organ may differentially retain some materials and permit other materials to escape with relative ease.

Ameloblasts↗

PubMed1990

The innervation of tracheal smooth muscle in the ferret.

The innervation of tracheal smooth muscle in the ferret has been studied by monitoring pressure changes in a fluid-filled segment of trachea in pentobarbitone anaesthetized animals. Stimulation of the peripheral cut end of the vago-sympathetic trunk elicited increases in trachea segment pressure only when activity was evoked in non-myelinated efferent axons, myelinated axons were without effect. Such excitatory responses were blocked by atropine. After atropine and elevation of trachealis muscle tone with 5-hydroxytryptamine, stimulation of the vago-sympathetic trunk produced a fall in tracheal segment pressure. These inhibitory responses were completely blocked by bretylium tosylate in six animals and markedly reduced in a seventh. It is concluded that contraction of tracheal smooth muscle in the ferret is cholinergically mediated and solely dependent on activity in non-myelinated vagal efferent axons and that inhibition is mediated by noradrenaline released from sympathetic nerve endings. A non-adrenergic inhibitory system would not appear to be present in the ferret.

Animals↗

PubMed1985

A demonstration of two distinct geniculocortical projection patterns in albino ferrets.

The geniculocortical pathways of albino ferrets have been studied by injecting lectin bound horseradish peroxidase into the visual cortex and then studying the geniculate distribution of retrogradely labelled cells in the dorsal lateral geniculate nucleus. It has been shown that in ferrets, as in Siamese cats, there are two quite distinct patterns of geniculocortical projection. One of the patterns seen in ferrets is comparable to the 'Midwestern' pattern previously described in Siamese cats, while the other is comparable to the 'Boston' pattern.

Albinism↗

PubMed1993

Estrogen receptor immunoreactive neurons in the fetal ferret forebrain.

The development of estrogen receptors was studied in the preoptic area/anterior hypothalamus (POA/AH) of fetal male and female ferrets. In males this region includes a nucleus (MN-POA/AH), delineated by Nissl stains, which is not discernible in females. The results reveal the distribution of estrogen receptor containing cells during the period when estrogen is known to induce the differentiation of the male ferret's MN-POA/AH. Brains were taken from ferret kits on days 30, 34, 37 and 40 of a 41-42 day gestation, and were processed utilizing the H222 monoclonal antibody to reveal estrogen receptors. At E30 there were numerous H222 immunoreactive (ir) cells in central regions of the POA/AH. From E30 to E40 there was a striking increase in the number of H222ir cells in the POA/AH. A broad sweep of H222ir cells extended from the ventral POA dorsally and laterally into the caudal POA and AH of both males and females. H222ir cells were not restricted to the region of the MN-POA/AH at any fetal age. H222 immunoreaction product at E30 was restricted to nuclear compartments. By E40, H222ir processes extended from some cells with H222ir nuclei in the medial and lateral POA/AH in both males and females. At the older fetal ages immunopositive cell numbers increased in lateral positions. At E34 and E37 (but not E30) selective ventricular zones, and regions between the hypothalamus and amygdala contained H222ir cells, suggesting the presence of estrogen receptors in cells during migration. Although the amygdala contained a few H222ir cells as early as E34, the cortex lacked H222ir cells even as late as E40. The appearance of H222ir cells in positions suggestive of migration is consistent with the hypothesis that estrogen receptors play some role in determining cell positions in certain regions of the developing nervous system.

Animals↗

PubMed1981

Antiviral effects of single-stranded polynucleotide inhibitors of the influenza virion-associated transcriptase against influenza virus infection of hamsters and ferrets.

Administration of a single-stranded polynucleotide copolymer containing 9% cytidine residues and 91% 4-thiouridine residues [poly(C,S4U10)], a known potent inhibitor of the virion transcriptase of influenza viruses, suppressed the amount of virus recoverable from the nasal washes of influenza virus-infected hamsters and ferrets. The incidence of sneezing and nasal discharge in infected ferrets was also reduced. In hamsters, poly(C,S4U10) was more effective than amantadine-HCl or Virazole. Polyinosinic acid in combination with poly-5-hydroxy cytidylic acid also had anti-influenza effects. Poly(C,S4U10) annealed to polyadenylic acid was not effective, nor was the double-stranded polymer (polyinosinic acid) . (polycytidylic acid) even when complexed with carboxymethylcellulose and polylysine. No toxic effects of poly(C,S4U10) were apparent in the treated hamsters and ferrets, and high doses (greater than or equal to 2.86 g/kg) administered intraperitoneally to mice produced no adverse effects.

Animals↗

PubMed1994

Evidence for cholinergic vagal afferents and vagal presynaptic M1 receptors in the ferret.

The distribution of muscarinic receptor binding was examined in the ferret brainstem vagal nuclei using the non-selective ligand [3H]quinuclidinyl benzilate and the relatively M1 receptor-selective ligand [3H]pirenzepine. The highest density of receptor sites are found in the subnucleus gelatinosus and lower levels in the other subnuclei of the nucleus of the tractus solitarius and in the area postrema and dorsal motor nucleus of the vagus nerve. Dense binding was also seen in the adjacent hypoglossal nucleus. Following unilateral cervical nodose ganglion excision binding in the subnucleus gelatinosus was attenuated ipsilateral to the lesion compared with the contralateral side. In contrast, [3H]pirenzepine binding was only seen in the subnucleus gelatinosus and in no other region at this level of the brainstem. This binding was reduced in the subnucleus as a whole by 52% ipsilateral to a cervical vagotomy. In the more rostral parts of the subnucleus gelatinosus, binding was undetectable ipsilateral to the lesion but more caudally, appreciable levels of binding persisted. This distribution parallels the known rostro-caudal variation in cross-over of vagal afferent fibres in the ferret dorsal vagal complex and indicates a presynaptic localization of [3H]pirenzepine binding sites on vagal afferent terminals. The distribution of binding of the high affinity choline uptake site blocker, [3H]hemicholinium-3, was also examined in the ferret brainstem using autoradiography. High densities of [3H]hemicholinium-3 binding were seen in the hypoglossal nucleus, the subnucleus gelatinosus and in the area postrema, with lower levels in the dorsal motor nucleus of the vagus, the trigeminal nucleus and other subnuclei of the nucleus of the tractus solitarius.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

The effects of cyanide and its interactions with norepinephrine on isolated aorta strips from the rabbit, dog, and ferret.

Effects of sodium cyanide on isolated strips of rabbit, dog, and ferret aorta were determined. In the rabbit aorta strip, cumulatively added cyanide caused small contractions beginning at approximately 10(-11) M cyanide and reaching a maximum response at 10(-5) M. A concentration of cyanide between 10(-5) M and 10(-3) M produced relaxation. When cyanide was cumulatively added to norepinephrine (NE)-contracted rabbit aorta strips, no contractions were observed. Cyanide concentrations above 10(-5) M produced relaxation in the NE-contracted vessels. Sensitivity of the aorta strips to NE differed among the species examined. The ED50 for contractions in the dog and ferret aorta was 4 X 10(-4) M and in the rabbit was 5 X 10(-6) M. Pretreatment with cyanide in concentrations up to 10(-2) M did not reduce contractions of dog aorta to NE, although 10(-2) M cyanide abolished contractions of rabbit aorta to NE and reversed NE-contractions of ferret aorta to relaxation. The antagonism of cyanide for NE-induced contractions was completely reversible with cyanide concentrations up to 10(-3) M. Cyanide pretreatment of strips of aorta increased the rate of contraction to NE. A concentration of 10(-2) M cyanide caused small contractions of aorta strips from each species. Thus, cyanide exerts dose and species dependent responses on vascular smooth muscle.

Animals↗

PubMed1986

Neonatal exposure of female ferrets to testosterone alters sociosexual preferences in adulthood.

Sociosexual preferences in adult female ferrets, as measured in a choice arena, were altered by neonatal exposure to exogenous testosterone. Adult female ferrets showed a preference for males which did not depend on the presence of gonadal steroids, because gonadectomized and gonadectomized estrogen-treated females showed identical preferences for males. Adult castrated males showed no preference for females unless these males were treated with testosterone. A similar no-preference pattern was found in adult females that had received testosterone neonatally. Females exposed neonatally to dihydrotestosterone or estradiol exhibited the normal females' male-oriented preference. These results indicate that testosterone secreted by the testes in the developing male may interrupt the phenotypic female development pattern and hence prevent the emergence of a homosexual preference in adulthood in the male ferret.

Animals↗

PubMed1988

Connections of a vagal communicating branch in the ferret. II. Central projections.

There is increasing interest in the central mechanisms involved in the regulation of gastrointestinal function. The ferret is becoming widely used for research in this area. However, knowledge of the brain stem organization of this species is inadequate. As part of an on-going study designed to provide information regarding the site of termination of abdominal afferents, the central connections of a supradiaphragmatic vagal communicating branch were determined in the ferret through the use of the horseradish peroxidase (HRP) tracing technique. The branch was exposed using a thoracotomy and HRP crystals were applied to the cut ventral end of the branch. Following a 72 hour survival period, the animals were reanesthetized and perfused. The brain stem was removed and processed using the tetramethylbenzidine method. Afferent terminals were found bilaterally in the nucleus of the solitary tract (nTS), area postrema (AP), the dorsal motor nucleus of the vagus (DMV), the external cuneate nucleus (ECN) and the principal subnucleus of the inferior olive (IOP). This is the first study of a brain stem projection of a specific vagal branch in this species, and demonstrates the similarities and differences which exist between the ferret and other species.

Animals↗

PubMed1990

Epithelium-derived PGE2 inhibits the contractile response to cholinergic stimulation in isolated ferret trachea.

We have previously reported that epithelium-dependent inhibitory factors, both prostanoids and non-prostanoids, can be activated by electrical field stimulation (EFS) and direct nerve stimulation (DNS) in an in vitro nerve-muscle preparation of ferret trachea. In this study we set out to compare the release of the inhibitory prostanoids, PGE2 and PGI2, in preparations with intact and with removed epithelium. Ferret tracheae were mounted in organ baths and phasic contractions were induced by EFS and DNS. The bath concentrations of PGE2 and the PGI2-metabolite 6-keto-PGF1 alpha were measured using radioimmuno assays. The gradual decrease in contractile response to DNS, 2 Hz for 120 min, was 95 +/- 2% of baseline (mean +/- SEM) in preparations with intact epithelium compared with 29 +/- 8% in epithelium-denuded preparations (p less than 0.001). The bath-levels of PGE2 showed a slight but significant (p less than 0.01) increase in denuded preparations with a final bath-concentration at 120 min of 13 +/- 3 pg/ml. The release of PGE2 was more pronounced in preparations with intact epithelium which resulted in a final bath-concentrations of PGE2 of 84 +/- 38 pg/ml which was significantly higher compared with epithelium-denuded preparations and also compared with time-matched controls with the same pattern of contraction induced by DNS alone. The concentrations of 6-keto-PGF1 alpha showed a slight increase which was of comparable magnitude (ns) in intact and denuded preparations. In conclusion this study demonstrates that the cyclooxygenase-dependent component of the epithelium-dependent inhibition of the contractile response to cholinergic nerve stimulation in ferret trachea is mediated by PGE2 but not by PGI2.

6-Ketoprostaglandin F1 alpha↗

PubMed2004

Craniofacial growth in the ferret (Mustela putorius furo)--a cephalometric study.

OBJECTIVE: When suggesting the ferret as a valid laboratory model in craniofacial research, it is essential to know about its normal craniofacial growth. DESIGN: Sixteen ferret kits (eight male and eight female) were selected for the present investigation. Serial lateral and dorsoventral cephalograms were taken on each animal at a mean age of 25, 35, 55, 80 and 300 days. The cephalograms were then digitised and the coordinates of 33 landmarks were derived on each set of cephalograms. Thirty-four variables were then calculated on each set of cephalograms by computer image programs with the coordinate data. Results were analysed statistically, and the craniofacial growth pattern and related sexual dimorphism were described in three perspectives: lateral and dorsoventral viscero- and neurocranium, and lateral mandible. FINDINGS: In both sexes, the viscero- and neurocranium follow an orderly pattern of expansive growth in three dimensions. The growth of the mandible is mainly characterised by an anteroposterior elongation of the mandibular body, an enlargement of the coronoid process, and an increase in height of the alveolar process. The growth rate varies with site. Craniofacial growth in ferrets starts to slow down and finally ceases earlier in female than in male animals.

Animals↗

PubMed2004

Functional influence of masticatory muscles on the fibre characteristics and capillary distribution in growing ferrets (Mustela putonusfuro)--a histochemical analysis.

OBJECTIVE: Changes in the masticatory function of ferrets have been shown to cause alterations in their craniofacial morphology. The aim of the present study was to investigate how the functional changes influence the histochemical characteristics of fibres of the masticatory muscles of the animal. DESIGN: Forty five-week old male ferrets were divided into two groups: one group was fed a diet of hard pellets (HD group), and one group was fed the same diet but softened with water (SD group). After 6 months, specimens of temporalis, masseter and digastricus were taken from each ferret and prepared for enzyme histochemical analysis RESULTS: Type I muscle fibres constituted the majority of the temporalis and the masseter, while the digastricus mainly comprised type II muscle fibres. The fibre-type composition did not differ significantly between the two groups. The mean cross-sectional area of type I and type II fibres in the temporalis and the masseter, and type II fibres in the digastricus was significantly greater in the HD group than the SD group. Furthermore, the HD group had a significantly greater number of capillaries per fibre, but not per surface unit (mm2). CONCLUSIONS: The results suggest that the muscle fibre size and the number of capillaries per fibre of the masticatory muscles are readily adaptesd to the altered masticatory muscle functions.

Animals↗

PubMed2006

Energetics of swimming by the ferret: consequences of forelimb paddling.

The domestic ferret (Mustela putorius furo) swims by alternate strokes of the forelimbs. This pectoral paddling is rare among semi-aquatic mammals. The energetic implications of swimming by pectoral paddling were examined by kinematic analysis and measurement of oxygen consumption. Ferrets maintained a constant stroke frequency, but increased swimming speed by increasing stroke amplitude. The ratio of swimming velocity to foot stroke velocity was low, indicating a low propulsive efficiency. Metabolic rate increased linearly with increasing speed. The cost of transport decreased with increasing swimming speed to a minimum of 3.59+/-0.28 J N(-1) m(-1) at U=0.44 m s(-1). The minimum cost of transport for the ferret was greater than values for semi-aquatic mammals using hind limb paddling, but lower than the minimum cost of transport for the closely related quadrupedally paddling mink. Differences in energetic performance may be due to the amount of muscle recruited for propulsion and the interrelationship hydrodynamic drag and interference between flow over the body surface and flow induced by propulsive appendages.

Animals↗

PubMed2006

Sperm viability in the black-footed ferret (Mustela nigripes) is influenced by seminal and medium osmolality.

Fundamental knowledge of spermatozoa cryobiology can assist with optimizing cryopreservation protocols needed for genetic management of the endangered black-footed ferret. Objectives were to characterize semen osmolality and assess the influence of two media at various osmolalities on sperm viability. We examined the influence of Ham's F10 +Hepes medium (H) at 270, 400, 500 or 700 mOsm (adjusted with sucrose, a nonpermeating cryoprotectant) and TEST Yolk Buffer (TYB) with 0% (300 mOsm) versus 4% (900 mOsm) glycerol (a permeating cryoprotectant). Electroejaculates (n=16) were assessed for osmolality using a vapor pressure osmometer. For media comparison, semen (n=5) was collected in TYB 0%, split into six aliquots, and diluted in H270, H400, H500, H700, and TYB 0% or TYB 4%. Each sample was centrifuged (300 g, 8 min), resuspended in respective medium, and maintained at 37 degrees C for 3h. Sperm motility and forward progression were monitored every 30 min for 3h post-washing. Acrosomal integrity was monitored at 0 and 60 min post-washing. Results demonstrated that black-footed ferret semen has a comparatively high osmolality (mean+/-SEM, 513.1+/-32.6 mOsm; range, 366-791 mOsm). Ferret spermatozoa were sensitive to hyperosmotic stress. Specifically, sperm motility was more susceptible (P<0.01) to hyperosmotic conditions than acrosomal integrity, and neither were influenced (P>0.05) by hypotonic solutions. Exposure to TYB 4% glycerol retained more (P<0.01) sperm motility than a hyperosmotic Ham's (700 mOsm). These findings will guide the eventual development of assisted breeding with cryopreserved sperm contributing to genetic management of this rare species.

Acrosome↗

PubMed2004

Ferrets: wound healing and therapy.

In all species of mammals, the stages of wound healing are the same, and both host factors and wound characteristics affect how wounds heal. The basic principles of wound care in ferrets, such as lavage, bandaging, and surgical closure, are similar to those in other species; however, knowledge of ferrets' anatomy and pathophysiology, as well as skin conditions commonly seen in ferrets, will help ensure proper wound healing.

Animals↗

PubMed2005

Viral diseases of ferrets.

Distemper and rabies vaccination are highly recommended because of the almost invariable fatal outcome of these conditions. Vaccination should constitute an important part of a ferret's preventative medicine program. With the current and anticipated development and licensing of new vaccines, practitioners are invited to gain awareness of the latest vaccine information. Establishment of a practice vaccination protocol with regards to the site of administration of rabies and distemper vaccines is paramount to document any future abnormal tissue reactions. Influenza is the most common zoonotic disease that is seen in ferrets. Although it generally is benign in most ferrets, veterinarians must take this condition seriously. The characteristic continuous antigenic variation of this virus may lead to more virulent strains; the recent emergence of avian influenza virus outbreaks; and the increased susceptibility of elderly, young, and immunosuppressed individuals.

Animals↗

PubMed2006

Eosinophilic gastroenteritis in three ferrets.

Eosinophilic gastroenteritis (EGE) is a rarely reported condition of ferrets. This article reviews three cases of suspected EGE in ferrets, summarizes the presenting signs, differential diagnoses, and treatment options, and discusses some question raised by this disease in ferrets. Immune suppression by means of prednisolone therapy is currently the treatment of choice.

Animals↗

PubMed2005

Dopamine D2, but not D4, receptor agonists are emetogenic in ferrets.

Agents that activate the dopamine D2-like family of receptors elicit emesis in humans and other species with a vomiting/emetic reflex; however, the lack of dopamine receptor subtype selective agonists has hampered an understanding of which dopamine D2-like receptor subtype(s) contributes to the emetic response. In this study, stable cell lines expressing the ferret dopamine D2-long (D2L) and D4 receptors were used to characterize known dopamine agonists via radioligand binding and calcium ion flux assays, while emetic activity of these dopamine receptor agonists was determined in male ferrets. Latencies to first emetic event, average number of emetic episodes, and stereotypical behaviors which may be indicative of nausea were also determined. Agonists at dopamine D1-like and D4 receptors had no emetic effect in ferrets. Conversely, stimulation of dopamine D2 and/or D3 receptors resulted in a robust emetic response characterized by a relatively short latency (<15 min) and multiple emetic events. Competitive antagonists of dopamine D2-like receptors (domperidone, haloperidol) dose-dependently blocked the emetic response to PNU95666E, a dopamine D2 receptor selective agonist. Thus, dopamine D2 and/or D3 receptor agonists elicit emesis, while dopamine D1/D5 or D4 receptor-selective agonists are devoid of emetic properties.

Animals↗