Germocyte lesions caused by porcine circovirus type 2b in Kunming mice.

Porcine circovirus type 2 (PCV2) has been known as a causative agent of reproductive failure in the sow. In the present study mouse model was used to investigate PCV2 infection. In order to investigate whether PCV2 can induce lesions of spermatocytes and oocytes, 6 male and 6 female mice were each inoculated intraperitoneally with PCV2b, and 3 male and 3 female mice mock-infected with cell culture supernatant served as controls. Samples of testes and ovaries from PCV2b-inoculated and mock-infected mice were investigated using PCR, histopathological, ultrastructural and immunofluorescent histochemical methods at 14 and 21 day post infection (dpi). The study revealed that in the virus-inoculated mice leydig cells in testes and granulosa cells in ovaries were degenerated, and a small number of spermatocytes and oocytes showed apoptosis. Positive PCV2b antigen signals were also observed in these apoptotic cells. It can be suggested that PCV2 can cause lesions of spermatocyte and oocyte prior to zygotes formation in its host.

[A retrospective analysis on occult neck lymphatic metastasis in early tongue cancer].

Objective: To investigate the number and level of occult neck lymphatic metastasis for squamous cell carcinoma of tongue in clinical stage Ⅰ/Ⅱ, and the relationship between cell differentiation and occult neck lymphatic metastasis. Methods: A total of 101 cases diagnosed preoperatively as having squamous cell carcinoma of tongue in clinical stage Ⅰ/Ⅱ (cT1/T2N0M0) between January 2005 and April 2015 were analysed retrospectively. Whether presence of occult neck lymphatic metastasis in these cases was studied. Results: Occult neck lymphatic metastases were found in 22 (21.78%) of 101 cases, 10 men and 12 women, with an age range of 22 to 83 years. There was not statistically significant association between tumor size or cell differentiation and occult neck lymphatic metastasis (P>0.05). The metastasis occurred most commonly in level Ⅱ, followed by levelsⅠ, Ⅲ and Ⅳ. There was no lymph node metastasis in Level Ⅴ. There were total 20 cases with occult neck lymphatic metastasis in at least one of levelⅠ, Ⅱ, Ⅲ(90.9%), One of these case was skipping metastasis in level Ⅲ(4.6%). Conclusion: The early tongue cancer has a high rate of occult lymph metastasis, which occurs commonly in levels Ⅱ, Ⅰ and Ⅲ, but there is not significant association between the metastasis and tumor size or cell differentiation.

GABA(A) receptors in the rostral ventrolateral medulla mediate the depressor response induced by stimulation of the greater splanchnic nerve afferent fibres in rats.

Experiments have been carried out to investigate the chemical substrate in the rostral ventrolateral medulla (RVLM) underlying the depressor responses induced by activation of the greater splanchnic nerve (GSPL) afferent fibres of the rat. In anaesthetised rats with urethane and alpha-chloralose, microinjection of bicuculline, a GABA(A) receptor antagonist, into the RVLM, attenuated largely the depressor responses elicited by electrical stimulation of the GSPL afferent fibres, while strychnine or saline had no effect. In 18 RVLM neurons (including seven identified cardiovascular neurons), iontophoresis of bicuculline also significantly blocked the inhibition evoked by stimulation of the GSPL afferent inputs. We suggest that the depressor responses induced by stimulation of the GSPL afferent fibres involve a GABA(A)-receptor-mediated mechanism in the RVLM in rats.

Convergence of midbrain, visceral and somatic inputs onto neurons in the nucleus paragigantocellularis lateralis in rats.

Extracellular recordings were made in nucleus paragigantocellularis lateralis (PGL) of the rat in response to stimulation of the dorsal periaqueductoral gray matter (dPAG), ventrolateral periaqueductuctoral gray matter (vPAG), deep peroneal nerve (DPN), median nerve (MN) and great splanchnic nerve (GSPL). Stimulation of dPAG or MN evoked mainly excitatory responses while the responses to stimulation of vPAG were inhibitory. However, stimulation of GSPL or DPN produced both inhibitory and excitatory responses. These neurons were not only responsive to one stimulation site, but were likely responsive to any other stimulation sites. Eighty-nine percent of cells tested (73/82) received convergent inputs from two or more sites. Sixty percent (21/35) of the neurons were identified as cardiovascular units based on their barosensitivity and slow conduction velocities of the descending axons projecting into the spinal cord. This result provided new evidence for the integrative function of neurons in PGL under some circumstances.

[The effects of stimulation of nucleus raphe obscurus on Fos-expression evoked by activiting dorsal periaqueductal gray and unit discharge in ventral periaqueductal gray in rat].

Experiments were carried out on rats anaesthetized with sodium pentobarbital or urethane and alpha-chloralose. Nucleus raphe obscurus (NRO) and dorsal periaqueductal grey (dPAG) were stimulated singly or simultaneously by square-wave pulses to induce the Fos-expression in midbrain and medulla oblongata. During the period of NRO stimulation, the basal blood pressure was increased (P < 0.05), the defensive pressor response to stimulation of dPAG was attenuated (P < 0.01). When both NRO and dPAG were stimulated, Fos- like immunoreactive (FLI) cells in the ventral periaqueductal grey (vPAG) and paragigantocellularis lateralis (PGL) were increased as compared with cases in which the stimulation was only delivered to dPAG, i.e., reaching a FLI cell count value of 66.5 +/- 8.3 and 10.8 +/- 1.5 respectively. Stimulation of the NRO with single or paired stimulus evoked both excitatory (84%) and inhibitory (16%) responses of the units in vPAG. Bilateral microinjection of lidocaine (2 micrograms in 0.1 microliter/side) into vPAG attenuated the depressor responses induced by stimulation of NRO, but little change in basal blood pressure (P > 0.01). It is suggested that there exist different types of neurons possessing different functions in the ventral lateral medulla (VLM) and NRO and that an excitatory projection from the NRO to vPAG may mediate the sympathoinhibitory effect of the nucleus.

[Morphine-3-glucuronide (M3G) potentiates noxious stimulus-evoked Fos protein-like immunoreactivity in the rat spinal cord].

The effect of morphine-3-glucuronide (M3G) on noxious stimulus-evoked Fos protein-like immunoreactivity in the rat spinal cord were assessed by ABC method. It was found that a dose-dependent increase of Fos-like immunoreactive neurons could be induced by M3G intrathecal injection followed by formaline injection into hindpaw. With high dosage M3G (1.1 x 10(-7) mole), dense Fos-like labelling was found in the superficial and the deep dorsal horn bilaterally, While with low dosage M3G (5.4 x 10(-8) and 1.1 x 10(-8) mole), most of the positively labelled neurons were only found in laminae I and II of the ipsilateral dorsal horn to the injured paw. The above results revealed that M3G exerts a potentiating effect on the noxious stimulus-evoked Fos protein-like immunoreactivity in the rat spinal cord.

Cardiovascular and renal effects of gamma-MSH in spontaneously hypertensive and normotensive Wistar Kyoto rats.

The objective of this study was to compare the cardiovascular and renal effects of the two gamma-melanocyte-stimulating hormone (MSH) peptide sequences in the pro-opiomelanocortin prohormone structure in conscious, anesthetized, and pithed spontaneous hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) controls. In the conscious but not in the pithed rats, intravenous injection of gamma 2- and gamma 1-MSH induced a rapid and dose-dependent increase in mean arterial pressure (MAP), and gamma 2-MSH was more potent than gamma 1-MSH. The pressor response was more pronounced and more sustained in the SHR compared with the WKY. There were dose-dependent and significant increases in heart rate (HR) after gamma 2- and gamma 1-MSH in the SHR. At intravenous infusions of low doses of gamma 2-MSH, which did not significantly influence MAP or HR, urinary sodium excretion was significantly increased in both SHR and WKY. In conscious, but not in anesthetized rats, intracerebroventricular administration of the gamma 2-MSH peptide induced sustained increases in MAP in both SHR and WKY. After intrathecal administration, there were transient pressor effects of gamma 2-MSH. We conclude that the pro-opiomelanocortin-derived gamma 2- and gamma 1-MSH peptide sequences possess potent rapid pressor actions. The pressor effects, which require an intact sympathetic nervous system, are more pronounced in the SHR strain. Moreover, gamma 2-MSH induces natriuresis when administered in nonpressor doses in WKY and SHR.

Convergent inputs to neurones in the nucleus paragigantocellularis lateralis in the cat.

Extracellular recordings were made in the nucleus paragigantocellularis (PGL) of the cat in response to stimulation of the hypothalamic perifornical defence area (HPDA), dorsal periaqueductal grey matter (PAG), nucleus raphe obscurus (Rob), deep peroneal nerve (DPN), and superficial peroneal nerve (SPN). Stimulation of the HPDA, dorsal PAG and SPN evoked excitatory responses whilst the prevalent response to stimulation of Rob was inhibition. However, most of the defence-reaction-related neurones showed little response to stimulation of DPN. Of 53 cells tested 48 (91%) received convergent inputs from two or more sites of stimulation. These findings are discussed in relation to the integrative function of PGL in cardiovascular control.

Antinociceptive and ventilatory effects of the morphine metabolites: morphine-6-glucuronide and morphine-3-glucuronide.

Morphine and its major metabolites, morphine-3-glucuronide and morphine-6-glucuronide, were given intracerebroventricularly (i.c.v.) to rats. The antinociceptive effects were assessed in the tail-flick and hot-plate tests as well as the writhing test. Ventilatory effects were studied in halothane-anaesthetized rats. Based on calculated ED50 values, morphine-6-glucuronide was approximately 200 times more potent that morphine itself in the tail-flick and hot-plate tests. In the writhing test the difference in ED50 was approximately 9-fold. Morphine and morphine-6-glucuronide administered i.c.v. induced dose-related decreases in minute ventilation in the dose range 2.7 x 10(-9)-1.3 x 10(-7) mol. The dose-response curve for minute ventilation was steeper for morphine-6-glucuronide than for morphine. Morphine-6-glucuronide was approximately 10 times more potent than morphine in depressing minute ventilation. Morphine-6-glucuronide reduced both tidal volume and respiratory frequency, while morphine reduced only the tidal volume. Morphine-3-glucuronide, in contrast, increased both tidal volume and respiratory frequency, causing an increase in minute ventilation. Apnoea was elicited after the highest doses of morphine-6-glucuronide but not of morphine. The potency difference for depression of minute ventilation between morphine-6-glucuronide and morphine corresponded well to the difference in the writhing test but not to the potency difference in the tail-flick or hot-plate tests. The ventilatory depression induced by morphine and morphine-6-glucuronide was readily reversed by naloxone, while the hyperventilation caused by morphine-3-glucuronide was slightly potentiated by the opioid antagonist. Naloxone pretreatment completely blocked the ventilatory depression induced by morphine-6-glucuronide. These results show that the potent ventilatory depression induced by morphine-6-glucuronide is related to its antinociceptive effects in rats. Furthermore, the fact that morphine-3-glucuronide stimulated ventilation and that morphine had a more shallow ventilatory dose-response curve compared to morphine-6-glucuronide may indicate that morphine-3-glucuronide is a functional antagonist of the depressive effects of morphine and morphine-6-glucuronide on ventilation.