Specific involvement of gonadal hormones in the functional maturation of growth hormone releasing hormone (GHRH) neurons

Growth hormone (GH) is the key hormone involved in the regulation of growth and metabolism, two functions that are highly modulated during infancy. GH secretion, controlled mainly by GH releasing hormone (GHRH), has a characteristic pattern during postnatal development that results in peaks of blood concentration at birth and puberty. A detailed knowledge of the electrophysiology of the GHRH neurons is necessary to understand the mechanisms regulating postnatal GH secretion. Here, we describe the unique postnatal development of the electrophysiological properties of GHRH neurons and their regulation by gonadal hormones. Using GHRH-eGFP mice, we demonstrate that already at birth, GHRH neurons receive numerous synaptic inputs and fire large and fast action potentials (APs), consistent with effective GH secretion. Concomitant with the GH secretion peak occurring at puberty, these neurons display modifications of synaptic input properties, decrease in AP duration, and increase in a transient voltage-dependant potassium current. Furthermore, the modulation of both the AP duration and voltage-dependent potassium current are specifically controlled by gonadal hormones because gonadectomy prevented the maturation of these active properties and hormonal treatment restored it. Thus, GHRH neurons undergo specific developmental modulations of their electrical properties over the first six postnatal weeks, in accordance with hormonal demand. Our results highlight the importance of the interaction between the somatotrope and gonadotrope axes during the establishment of adapted neuroendocrine functions

Determinação sérica de haptoglobina, ceruloplasmina e alfa-glicoproteína ácida em cães com gastrenterite hemorrágica Determination of serum haptoglobin, ceruloplasmin and acid alpha-glycoprotein in dogs with haemorrhagic gastroenteritis

As proteínas de fase aguda (PFA) são proteínas plasmáticas, cujo estímulo à síntese ocorre de forma rápida e marcante em resposta à injúria tecidual. Estas proteínas permitem o diagnóstico de processos inflamatórios em animais com supressão ou depressão medular. Além disso, são úteis na monitorização da resolução tecidual de traumas ou inflamação e também na avaliação da resposta orgânica ao tratamento. Uma vez que a leucopenia é observada nos estádios iniciais da parvovirose canina, a dosagem das PFA pode permitir a avaliação do processo inflamatório sob estas condições. Considerando-se estas hipóteses, foram determinados os níveis séricos das PFA (haptoglobina, ceruloplasmina e alfa-glicoproteína ácida) em 11 cães saudáveis e 11 cães leucopênicos com gastrenterite hemorrágica, com suspeita clínica de parvovirose canina. A avaliação estatística mostrou diferença significativa, com intervalo de confiabilidade de 99% (P<0,01) para a haptoglobina (p< 0,0064) e para a glicoproteína ácida (p< 0,0042) e 95% de confiança (P< 0,05) para a ceruloplasmina (p< 0,0478) quando comparada com o grupo controle. Em conclusão, cães com gastrenterite hemorrágica durante a fase leucopênica apresentaram níveis elevados de haptoglobina, ceruloplasmina e alfa-glicoproteína ácida.<br>Acute phase proteins (APP) are serum proteins whose stimulus for the synthesis happens in a quick and intense manner in response to tissue injury. Those proteins allow the diagnosis of inflammatory process in animals with bone marrow depression and, also, they are useful in the follow up of tissue resolution of traumas or inflammation, as well as in the evaluation of the organic response of the treatment. As leukopenia is observed in the initial stage of the canine parvovirus infection, the dosage of APP can allow the evaluation of the inflammatory process under these conditions. According to these hypothesis, serum APP levels (haptoglobin, ceruloplasm and a-acid-glycoprotein) in 11 healthy dogs and 11 leukopenic dogs with haemorrhagic gastroenteritis, clinically suspected of canine parvovirus infection, were measured. There was a significant difference, with confidence interval of 99% (P <0.01) for the haptoglobin (p <0.0064) and the acid alpha-glycoprotein (p <0.0042) and 95% (P <0.05) of confidence for the ceruloplasmin (p <0.0478) when compared to the control group. In conclusion, dogs with haemorrhagic gastroenteritis during the leukopenic phase showed high serum levels of haptoglobin, ceruloplasmin and alpha-acid-glycoprotein

Function of Dynein and Dynactin in Herpes Simplex Virus Capsid Transport

After fusion of the viral envelope with the plasma membrane, herpes simplex virus type 1 (HSV1) capsids are transported along microtubules (MTs) from the cell periphery to the nucleus. The motor ATPase cytoplasmic dynein and its multisubunit cofactor dynactin mediate most transport processes directed toward the minus-ends of MTs. Immunofluorescence microscopy experiments demonstrated that HSV1 capsids colocalized with cytoplasmic dynein and dynactin. We blocked the function of dynein by overexpressing the dynactin subunit dynamitin, which leads to the disruption of the dynactin complex. We then infected such cells with HSV1 and measured the efficiency of particle binding, virus entry, capsid transport to the nucleus, and the expression of immediate-early viral genes. High concentrations of dynamitin and dynamitin-GFP reduced the number of viral capsids transported to the nucleus. Moreover, viral protein synthesis was inhibited, whereas virus binding to the plasma membrane, its internalization, and the organization of the MT network were not affected. We concluded that incoming HSV1 capsids are propelled along MTs by dynein and that dynein and dynactin are required for efficient viral capsid transport to the nucleus