Characterization of serum protein fractions of dogs naturally infected with Ehrlichia canis or Anaplasma platys associated with uveitis.

Uveitis associated with Ehrlichia canis or Anaplasma platys infections were reported in dogs. However, only two E. canis-infected dogs with hypergammaglobulinemia showed acute blindness were reported. There were limited data of the species of Ehrlichia or Anaplasma and the alteration of serum protein fractions in infected dogs. Thus, the species of causative pathogen were investigated and compared the serum protein fractions between infected dogs associated with anterior uveitis and panuveitis in clinical situations. All 103 studied dogs were brought into the ophthalmology clinic which each dog showed signs of unilateral or bilateral uveitis related to ehrlichial infection. Dogs were divided into anterior uveitis and panuveitis groups. The species of Ehrlichia or Anaplasma were identified using nested-PCR based on the 16S rRNA gene and DNA sequencing from blood samples. The serum protein fractions were analyzed using electrophoresis. Fifty-eight dogs (56.31%) were positive of which E. canis and A. platys were detected in 51 and 7 dogs, respectively. The total serum protein and globulin levels were higher in the infected dogs associated with panuveitis than anterior uveitis while the albumin levels were significantly lower in the panuveitis group. The A/G ratios significantly decreased in both groups. Gamma globulin was detected at high levels in both groups while beta globulin significantly increased in the panuveitis group. Hypergammaglobulinemia was detected in 76.92 and 90.90% of infected dogs associated with anterior uveitis and panuveitis, respectively. Most of the infected dogs associated with panuveitis showed significantly levels of hyperproteinemia, hyperbetaglobulinemia and hypergammaglobulinemia compared with anterior uveitis group. E. canis was found as the major pathogen in infected dogs associated with uveitis in this study.

Characterization of serum protein fractions of dogs naturally infected with Ehrlichia canis or Anaplasma platys associated with uveitis

@#Uveitis associated with Ehrlichia canis or Anaplasma platys infections were reported in dogs. However, only two E. canis-infected dogs with hypergammaglobulinemia showed acute blindness were reported. There were limited data of the species of Ehrlichia or Anaplasma and the alteration of serum protein fractions in infected dogs. Thus, the species of causative pathogen were investigated and compared the serum protein fractions between infected dogs associated with anterior uveitis and panuveitis in clinical situations. All 103 studied dogs were brought into the ophthalmology clinic which each dog showed signs of unilateral or bilateral uveitis related to ehrlichial infection. Dogs were divided into anterior uveitis and panuveitis groups. The species of Ehrlichia or Anaplasma were identified using nested-PCR based on the 16S rRNA gene and DNA sequencing from blood samples. The serum protein fractions were analyzed using electrophoresis. Fifty-eight dogs (56.31%) were positive of which E. canis and A. platys were detected in 51 and 7 dogs, respectively. The total serum protein and globulin levels were higher in the infected dogs associated with panuveitis than anterior uveitis while the albumin levels were significantly lower in the panuveitis group. The A/G ratios significantly decreased in both groups. Gamma globulin was detected at high levels in both groups while beta globulin significantly increased in the panuveitis group. Hypergammaglobulinemia was detected in 76.92 and 90.90% of infected dogs associated with anterior uveitis and panuveitis, respectively. Most of the infected dogs associated with panuveitis showed significantly levels of hyperproteinemia, hyperbetaglobulinemia and hypergammaglobulinemia compared with anterior uveitis group. E. canis was found as the major pathogen in infected dogs associated with uveitis in this study.

Thrombocytopenia and anemia related to retinal detachment in dogs infected with Ehrlichia canis and Anaplasma platys.

In Thailand, five species of Ehrlichia (E. canis, E. chaffeensis, E. equi, E. risticii and Anaplasma platys) have been reported to infect dogs. Although ehrlichial infections can cause ocular disorders, the severity and type of ocular disorder varies between individual infected dogs. The aims of this study were to determine the factors associated with retinal detachment and to investigate the species of Ehrlichia that cause ocular disorders in natural infected dogs. In the present study, ocular examination, complete blood count and total protein measurement were performed in 134 dogs brought into an ophthalmology clinic. A 310 bp fragment of the Ehrlichia 16s rRNA gene was amplified by nested-PCR and direct DNA sequenced. Thirty-eight of these dogs were found to be positive for Ehrlichia 16s rRNA, of which the sequence analysis suggested 34 and 4 dogs were infected with E. canis and A. platys, respectively, with no multiple infections or other Ehrlichia species detected. The most common ocular disorders in dogs infected with E. canis were blindness, keratoconjunctivitis sicca and retinal detachment, while blindness and retinal detachment were found in A. platys-infected dogs. Hematological disorders were found anemia, thrombocytopenia and hyperproteinemia. Odd ratio analysis showed that thrombocytopenia and anemia were likely important factors for increasing retinal detachment risk. In this study, only E. canis and A. platys closely relate to be causative agents of ocular disorders in infected dogs. To the best of our knowledge, this is the first report of A. platys as a causative pathogen of both anterior and posterior uveitis in clinical situations.

Dopamine and mesotocin neurotransmission during the transition from incubation to brooding in the turkey.

We investigated the neuroendocrine changes involved in the transition from incubating eggs to brooding of the young in turkeys. Numbers of mesotocin (MT; the avian analog of mammalian oxytocin) immunoreactive (ir) neurons were higher in the nucleus paraventricularis magnocellularis (PVN) and nucleus supraopticus, pars ventralis (SOv) of late stage incubating hens compared to the layers. When incubating and laying hens were presented with poults, all incubating hens displayed brooding behavior. c-fos mRNA expression was found in several brain areas in brooding hens. The majority of c-fos mRNA expression by MT-ir neurons was observed in the PVN and SOv while the majority of c-fos mRNA expression in dopaminergic (DAergic) neurons was observed in the ventral part of the nucleus preopticus medialis (POM). Following intracerebroventricular injection of DA or oxytocin (OT) receptor antagonists, hens incubating eggs were introduced to poults. Over 80% of those injected with vehicle or the D1 DA receptor antagonist brooded poults, while over 80% of those receiving the D2 DA receptor antagonist or the OT receptor antagonist failed to brood the poults. The D2 DA/OT antagonist groups also displayed less c-fos mRNA in the dorsal part of POM and the medial part of the bed nucleus of the stria terminalis (BSTM) areas than did the D1 DA/vehicle groups. These data indicate that numerous brain areas are activated when incubating hens initially transition to poult brooding behavior. They also indicate that DAergic, through its D2 receptor, and MTergic systems may play a role in regulating brooding behaviors in birds.

Dopamine-melatonin neurons in the avian hypothalamus controlling seasonal reproduction.

Day length cues are used by temperate zone birds to time seasonal changes in reproductive physiology and behavior. However, the neuronal and neurochemical circuits used to measure day length (photoperiodic time measurement; PTM), transduce light information and activate the reproductive neuroendocrine system have not been definitely established. Recent findings from our laboratory provide data showing dopamine (DA) neurons within the premammillary nucleus (PMM) of the caudal turkey hypothalamus are putative photoreceptive neurons. These neurons reach threshold activation when a brief pulse of light is provided during the photo-inducible phase for photosexual stimulation. To further clarify the role of PMM neurons in coding daylight information, we showed that by using double-label immunocytochemistry (ICC) these neurons are immunoreactive (ir) to both tyrosine hydroxylase (TH; the rate limiting enzyme in DA biosynthesis) and melatonin (MEL). Moreover, we found these neurons to express tryptophan hydroxylase 1 (TPH1; the first enzyme in MEL biosynthesis) and 5-HT N-acetyltransferase (AANAT; a key regulatory enzyme in MEL synthesis) mRNAs but not neuronal tryptophan hydroxylase 2 mRNA (TPH 2; the rate limiting enzyme in 5-HT pathway). Both TH and TPH1 mRNAs were shown to cycle rhythmically, and with opposite phases, in PMM neurons of birds kept under a diurnal illumination cycle (12-h light/dark; LD). These neurons could also generate 24 h TH and TPH1 mRNA expression rhythms with the same phase relationship in constant light (LL) and constant dark (DD). In addition, the expression patterns and amplitudes of TH and TPH1 mRNAs were different between long and short photoperiods. These findings may form the basis for an endogenous dual-oscillator circadian system within PMM DA-MEL co-localized neurons controlling reproductive seasonality in birds.

Rhythmic dependent light induction of gonadotrophin-releasing hormone-I expression and activation of dopaminergic neurones within the premammillary nucleus of the turkey hypothalamus.

Our previous studies using turkey hens have demonstrated that c-fos mRNA (a marker of neuronal activation) is expressed in gonadotrophin-releasing hormone-I (GnRH-I), vasoactive intestinal peptide (VIP) and dopamine (DA) neurones following electrical stimulation in the preoptic area. DA has been shown to have both stimulatory and inhibitory effects on the GnRH-I/luteinising hormone (LH), follicle-stimulating hormone (FSH) and VIP/prolactin (PRL) systems. To identify the DA neurones that mediate the stimulatory influences of photoperiod on the reproductive system, we examined c-fos mRNA induction in DA, GnRH-I, and VIP neurones in the turkey hypothalamus using a dark-interruption experimental design. A 30-min light period was provided to short day (6L : 18D) photosensitive turkeys at times when birds were responsive to light (14 h after first light) and at times when birds were unresponsive to light (8 h and 20 h after first light). The only area where DA neurones were activated when the birds were provided with light was in the nucleus premammillaris (PMM). The number of activated DA neurones was significantly greater when light was provided at 14 h (during the photoinducible phase) than at 8 h or 20 h. At 14 h, there was also an increase in the number of GnRH-I neurones activated in the area of the nucleus commissura pallii (nCPa), as well as an up-regulation of GnRH-I mRNA expression. No expression of c-fos mRNA was observed in VIP neurones in the nucleus infundibularis or up-regulation of VIP mRNA expression in any of the experimental light treatments. These results are the first evidence to demonstrate a relationship between the dopaminergic system in the PMM and the GnRH-I system in the nCPa during the photoinduction of avian reproductive activity.

Rhythm-dependent light induction of the c-fos gene in the turkey hypothalamus.

Day length (photoperiod) is a powerful synchroniser of seasonal changes in the reproductive neuroendocrine activity in temperate-zone birds. When exposed to light during the photoinducible phase, reproductive neuroendocrine responses occur. However, the neuroendocrine systems involved in avian reproduction are poorly understood. We investigated the effect of light exposure at different circadian times upon the hypothalamus and components of the circadian system, using c-fos mRNA expression, measured by in situ hybridisation, as an indicator of light-induced neuronal activity. Levels of c-fos mRNA in these areas were compared after turkey hens (on a daily 6-h light period) had been exposed to a 30-min period of light occurring at 8, 14, or 20 h after the onset of first light of the day (subjective dawn). Non-photostimulated control birds were harvested at the same times. In birds, photostimulated within the photoinducibile phase (14 h), in contrast to before or after, c-fos mRNA was significantly increased in the nucleus commissurae pallii (nCPa), nucleus premamillaris (PMM), eminentia mediana (ME), and organum vasculosum lamina terminalis (OVLT). Photostimulation increased c-fos mRNA expression in the pineal gland, nucleus suprachiasmaticus, pars visualis (vSCN) and nucleus inferioris hypothalami compared to that of their corresponding nonphotostimulated controls. However, the magnitudes of the responses in these areas were similar irrespective of where in the dark period the pulses occurred. No c-fos mRNA was induced in the nucleus infundibulari, in response to the 30-min light period at any of the circadian times tested. The lack of c-fos up-regulation in the pineal gland and vSCN following photostimulation during the photoinducible phase lends credence to the hypothesis that these areas are not involved in the photic initiation of avian reproduction. On the other hand, c-fos mRNA increases in the nCPa, ME, and OVLT support other studies showing that these areas are involved in the onset of reproductive behaviour initiated by long day lengths. The present study provides novel data showing that the PMM in the caudal hypothalamus is involved in the neuronally mediated, light-induced initiation of reproductive activity in the turkey hen.

Identification of dopamine, gonadotrophin-releasing hormone-I, and vasoactive intestinal peptide neurones activated by electrical stimulation to the medial preoptic area of the turkey hypothalamus: a potential reproductive neuroendocrine circuit.

The neural and neurochemical substrates regulating reproduction in birds remain vaguely defined. The findings that electrical stimulation in the medial preoptic area (ES/MPOA) or intracerebroventricular infusion of dopamine (DA) stimulated luteinising hormone (LH) and prolactin (PRL) release in female turkeys, led to the suggestion that ES/MPOA might help to clarify the DA circuitry regulating LH and PRL. We used c-fos mRNA and tyrosine hydroxylase immunoreactivity as measured by double in situ hybridisation/immunocytochemistry (ISH/ICC) to determine which group/subgroup of DA neurones was activated following unilateral ES/MPOA. To establish that the reproductive neuroendocrine system was activated, double ISH/ICC was also conducted on c-fos/gonadotrophin-releasing hormone-I (GnRH-I) and c-fos/vasoactive intestinal peptide (VIP). Changes in circulating LH and PRL were determined by radioimmunoassay. Unilateral ES/MPOA (100 microA, right side) of anaesthetised laying turkeys for 30 min increased circulating LH and PRL levels. It also induced c-fos mRNA expression on the ipsilateral side by all GnRH-I neurones within the septopreoptic region, implying that GnRH-I neurones in this region share similar circuitry. VIP neurones within the nucleus infundibularis were the only VIP group to show c-fos mRNA expression, suggesting their involvement in ES/MPOA induced PRL release. c-fos mRNA expression was also observed in a subgroup of DA neurones in the nucleus mamillaris lateralis (ML). To our knowledge, the present study is the first to show that activation of DAergic cells in the ML is associated with the activation of GnRH-I and VIP neurones and the release of LH and PRL. It is likely that ES/MPOA activated VIP/GnRH-I neurones via activation of DA neurones in the ML, as this was the only DA subgroup that showed c-fos mRNA expression.