Ultrasonography as a complementary exam in the diagnosis of oral arteriovenous malformation.

The Doppler ultrasonography (DU) in cases of arteriovenous malformations (AVMs) is not widely use by dentists and there are a lack of information on the topic in the literature. AVM is common in the region of the head and neck and are commonly confused with hemangiomas (congenital). Appropriate classification is essential for therapeutic decision. The diferential diagnosis is based on clinical history, diascopy, and, if necessary, diagnostic imaging. This article present two cases of oral AVM in which DU was crucial in detecting a venous and/or arterial component in purplish lesions in the tongue and buccal mucosa, with positive diascopy. In our cases, after DU, we found a predominance of blood component within the lesion and therefore both patients were referred to the head and neck surgeon for surgical removal of the lesion. Only in the presence of a venous component does outpatient treatment become feasible. Given the predominance of the arterial component, outpatient procedures are contraindicated. Therefore DU is an important supplementary test, being of great importance in the clinical decision and treatment plan for oral AVMs and should become a routine part of the dentist front of vascular lesions of medium to large size.

Opposite effects of substance P fragments C (anxiogenic) and N (anxiolytic) injected into dorsal periaqueductal gray.

Recent findings implicating neurokinins in the expression of anxiety-like behaviors have stimulated interest in the participation of these neuropeptides in the dorsal periaqueductal gray matter (dPAG), one of the main output regions of the brainstem for the expression of defense reaction. Studies on the behavior of rats submitted to the elevated plus-maze test in this laboratory have shown that microinjections of substance P into the dorsal periaqueductal gray produce anxiogenic-like effects. Now, we analyze what portion of the molecule of substance P is responsible for these effects through the examination of the action of its C- and N-terminus fragments (6-11 and 1-7) in the elevated plus-maze. We also investigated whether these effects are influenced by prior treatment with the tachykinin NK(1) receptor antagonist 17-beta-hydroxy-17-alpha-ethynyl-5alpha-androstanol[3,2-b]pyrimido[1,2-a]benzimidazole (WIN51,708). To this end, rats were implanted with a cannula in the dorsal periaqueductal gray and injected 1 week later with equimolar doses (17.5 and 35 pmol) of either C- or N-fragments of substance P and tested in the elevated plus-maze. The results show that the C-terminal fragment has an anxiogenic profile of effects, including reduction in the number of entries and time spent in the open arms of the maze, plus increases in scanning, stretched-attend posture, head dipping and flat-back approach. On the other hand, the N-terminal fragment produced opposite effects, namely, an increase in the number of entries and time spent in the open arms of the maze accompanied by an increase in end-arm activity, rearing and head dipping. The tachykinin NK(1) receptor antagonist WIN51,708 (20 mg/kg, i.p.) inhibited the effects of the carboxy-terminal of substance P while it did not change the effects of the N-terminal fragment. Microinjection of WIN51,708 (20 mg/kg, i.p.), by its own, did not produce any significant effects. Therefore, the results indicate that the anxiogenic effects of substance P injected into the dorsal periaqueductal gray are encoded by its carboxy-terminal sequence and due to its action on tachykinin NK(1) receptors.

Hyperanxiety produced by periaqueductal gray injection of chondroitin sulphate glycosaminoglycan.

We examined the effects of chondroitin sulphate C (CSC) on fear and anxiety parameters following injection of the glycosaminoglycan into the dorsal periaqueductal gray. Rats with chronically implanted cannulae were administered CSC (0.4 or 4.0 nmol) or vehicle (saline, 0.2 microl) and exposed to the elevated plus-maze test of emotionality. Intra-periaqueductal gray injection of CSC produced a dose-dependent anxiogenic effect as indicated by reduced entries into and time spent on the open arms, fewer excursions into the end of the open arms and by increased stretched attend posture, flat back approach and closed arm peeping-out behaviour. The behavioural effects of CSC appeared to be anxioselective, since the glycosaminoglycan did not influence measures of general (exploratory) activity, such as number of entries into the enclosed arms and amount of scanning, rearing and grooming. The present results show that CSC can produce an anxiogenic-like profile after injection into the dorsal periaqueductal gray. This is the first such report implicating an endogenous matrix glycosaminoglycan in neural mechanisms governing fear and anxiety.

Place aversion induced by microinjections of C-fragment of substance P into the dorsal periaqueductal gray of rats is mediated by tachykinin NK1 receptors.

Neural circuits in the dorsal periaqueductal gray matter (dPAG) play an important role in the integration of defensive behavior. The neurokinin substance P causes conditioned place aversion when administered into this region. The present study examined whether these effects may be mimicked by its carboxy-terminal amino acid sequence and whether they are influenced by prior treatment with the tachykinin NK1 receptor antagonist WIN51,708. The behavioral testing apparatus is a circular open field consisting of 4 uniform quadrants that are equally preferred by the rats prior to drug treatments. For conditioning, rats received drug injections on three consecutive days and were placed into their assigned quadrant. The carboxy-terminal analog (17.5 pmol/0.2 microl) applied into the dPAG produced place aversion effects with reduced time spent in the drug-paired quadrant on the testing day. The effects of the carboxy-terminal analog was antagonized by pretreatment with WIN51,708 (20 mg/kg, i.p.). Microinjection of WIN51,708 (20 mg/kg, i.p.), by its own, did not produce significant effects. These findings suggest that previous reports showing conditioned place aversion effects of SP injected into the dPAG are encoded by its carboxy-terminal sequence and due to its action on tachykinin NK1 receptors.

Neurochemical mechanisms of the defensive behavior in the dorsal midbrain.

Some regions in the mesencephalon, such as dorsal periaqueductal gray, inferior colliculus and deep layers of superior colliculus have been grouped together as a continuous strip of midbrain structures involved in the integration of the different components of aversive states in the brain. In fact, escape behavior and defensive, or fear-like behavior often result when these sites are electrically or chemically stimulated. Moreover, the behavioral responses induced by stimulation of these structures are, in general, accompanied by increases in mean arterial blood pressure, heart rate and respiration, and by analgesia. Both the behavioral and autonomic consequences of electrical stimulation of the mesencephalic tectum was shown to be attenuated by minor tranquilizers, probably through enhancement of GABAergic neurotransmission. Besides GABAergic interneurons which exert a tonic inhibitory control on neural circuits responsible for the behavioral correlates of the aversion in the above-mentioned structures, several other mechanisms such as opioid, neuropeptides, serotonergic and excitatory amino acids have also been implicated in the regulation of these processes. As to the analgesia that accompanies these aversive states it is mediated by non-opioid mechanisms, particularly by serotonergic ones through 5-HT2 receptors. Now, efforts have been made to characterize the mode of action of these neurotransmitters on their multiple receptors and how they interact with each other to produce or regulate the neural substrates of aversion in the midbrain.

Anxiogenic effects of substance P and its 7-11 C terminal, but not the 1-7 N terminal, injected into the dorsal periaqueductal gray.

The dorsal periaqueductal gray matter (DPAG) is one of the main output regions of the brainstem for the expression of defense reaction. Recent findings implicating neurokinins in the expression of fear or anxiety-like behaviors, have stimulated interest in the participation of these neuropeptides in the generation of aversive states in the dorsal periaqueductal gray matter. Analyses of traditional measures of the behavior of rats submitted to the elevated plus-maze test in this laboratory have shown that microinjections of substance P (SP) into the DPAG produce anxiogenic-like effects. The present study employs an ethological analysis of the behavior of animals in this test to investigate the involvement of substance P (SP) and its C- and N- fragments (7-11 and 1-7) in the expression of the different aspects of fear upon injection into the DPAG. To this end, rats were implanted with a cannula in the DPAG and injected one week later with 35 and 70 pmol of either substance P, or C- or N- SP fragments and tested immediately afterwards in the elevated plus-maze. The results show that SP and its C terminal fragment, produced increases in scanning, stretched attend posture, head dipping and flat-back approach, whereas the fragment N terminal produced only an increase in rearing. Therefore, the effects of SP and its C terminal fragment were associated to risk assessment behavior, whereas those of N terminal fragment were related to vertical exploratory activity. The results indicate that SP produces anxiogenic effects through activation of neural substrates of aversion in the DPAG and that this effect is probably related to its C terminal fragment.

Aversive effects of the C-fragment of Substance P in the dorsal periaqueductal gray matter.

There has been an increasing interest in the role of neuropeptides in the integration of brain functions. Besides the well-known positive-reinforcing effects of Substance P (SP) in prosencephalic regions, a role of this neuropeptide in the generation of aversive states in mesencephalic structures has also been envisaged. Evidence from a previous study suggests an involvement of SP in the neural substrates of aversion in the dorsal periaqueductal gray matter (DPAG). In the present study, we investigate whether N- and C-terminal fragments of Substance P are responsible for the effects produced by microinjections of SP into the dorsal periaqueductal gray. The results show that SP and its C-terminal fragment SP(7-11) produced a behavioral activation with increases in locomotor activity, grooming, and rearings, while the N-terminal fragment SP(1-7) produced only an increase in vertical exploratory activity. The effects were more pronounced with intermediate doses of SP and its C-fragment, confirming the characteristic bell-shaped dose-effect function of this neuropeptide. The proaversive effects observed with DPAG microinjections of these neuropeptides in the present study gain further relevance when combined with previous reports showing unconditioned and conditioned aversive effects following DPAG microinjections of SP in the place aversion and the elevated plus maze tests, two widely used animal models of anxiety. These results confirm previous data showing that SP has a modulatory role in the DPAG and that its effects are probably due to its C-terminal fragment.