Oral stereotypy induced by amphetamine microinjection into striatum: an anatomical mapping study.

The ventrolateral striatum has been shown to specifically contribute to expression of psychostimulant-induced orofacial stereotypies. Adult male Sprague-Dawley rats were implanted with bilateral cannulae directed at one of eight striatal subareas, and were injected with saline or amphetamine (20 micrograms/0.5 microliter/side) in a counterbalanced order. Behaviors were observed and scored using a time-sampling procedure. In the middle ventrolateral striatum, amphetamine injections produced intense stereotypy, primarily consisting of bar biting, non-injurious self-biting and repetitive paw-to-mouth movements, while having no effect on locomotion or rearing. Amphetamine injections 2 mm medial or 1 mm dorsal produced no oral stereotypy, while injections 1 mm rostral or caudal to the effective site produced only low levels of stereotypy. Injections into the surrounding sites, particularly in the ventromedial region, also had stimulatory effects on locomotion and rearing. In a separate experiment, animals were given either unilateral or bilateral injection of amphetamine into the ventrolateral striatum. The unilateral injection produced stereotypy half as intense as that observed with bilateral injections. These results suggest that the ventrolateral striatum is a discrete neuroanatomical region which is primarily responsible for expression of psychostimulant-induced orofacial stereotypies, and which is likely to be the striatal region controlling normal oral motor function. Further investigation of this area may provide valuable insights concerning the etiology and treatment of orofacial dyskinesias associated with basal ganglia dysfunction.

GRF-induced feeding: evidence for protein selectivity and opiate involvement.

Growth hormone-releasing factor (GRF) is a hypothalamic peptide named for its ability to induce release of growth hormone from the anterior pituitary. GRF also acts as a neurotransmitter in the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) to stimulate food intake. The purpose of this series of experiments was to explore the nature of GRF-induced feeding, with a particular emphasis on macronutrient selectivity, and to examine the role of opiate activity in the paraventricular nucleus of the hypothalamus (PVN). Chow intake stimulated by GRF microinjection (1 pmol/0.5 microliters) into the SCN/MPOA was blocked by injection of methyl-naltrexone (3 micrograms/0.5 microliters) into the PVN. In animals habituated to macronutrient diets (Teklad, WI), GRF preferentially stimulated intake of protein at 2 and 4 h postinjection, whereas it had no effect on carbohydrate intake. Further, this effect was blocked by injection of naloxone (40 nmol/0.5 microliters) into the PVN. Microinjection of morphine (0, 1, 10, and 17 micrograms/0.5 microliter) into the PVN also specifically stimulated protein intake at 2 and 4 h postinjection. These results suggest that feeding derived from GRF actions in the SCN/MPOA is macronutrient selective, and is dependent on PVN opiate activity for expression.

Blockade of endogenous GRF at dark onset selectively suppresses protein intake.

This study examined whether endogenous central GRF activity contributes to the increase in macronutrient intake shown by rats at dark onset. Animals were habituated to two diets: carbohydrate-fat and protein-fat. Antiserum raised against GRF (aGRF; 1% and 10% solutions) was microinjected into the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) at dark onset, and macronutrient intake was determined at 1, 2, and 4 h postinjection. aGRF blocked the increase in protein intake normally seen at dark onset, but had no effect on carbohydrate intake. These findings suggest that endogenous GRF activity in the SCN/MPOA region of the brain contributes to the circadian and nutritional organization of food intake.

Massive thymic hyperplasia in an adolescent.

Massive thymic hyperplasia (weight, greater than 100 gm) is a rare lesion in adolescents, and most of the anterior mediastinal masses are true neoplasms. We present a case of massive thymic hyperplasia, in which a 680-gm thymus was resected from a 15-year-old boy. We also present the computed tomographic scan appearance of this lesion, which differed from that previously described, and correlate the histological and radiological findings.

The dopamine D2 receptor agonists, quinpirole and bromocriptine produce conditioned place preferences.

1. The conditioned place preference paradigm was used to examine the role of the D2 receptor in mediating the reinforcing effects of dopamine (DA) agonists. 2. During the 3-day pre-exposure phase, rats explored two distinctive end compartments which were adjoined by a small tunnel. During the 8-day conditioning phase, groups of rats were treated with the selective D2 receptor agonists, quinpirole (0.01, 0.025, 0.05, 0.10, 0.25, 1.0 and 5.0 mg/kg IP) or bromocriptine (0, 0.01, 0.1, 0.5, 1.0, 5.0 and 10.0 mg/kg IP) and confined to one compartment for 30 min. On alternate days, rats received vehicle injections and were placed in the opposite compartment. Test days occurred over the remaining 3 days during which untreated animals explored both compartments. 3. Rats conditioned with quinpirole or bromocriptine showed significant increases in time spent in the drug-paired environment from pre-exposure to test indicating the establishment of conditioned place preferences. 4. This suggests a functional role for the D2 receptor in mediating the rewarding effects of DA agonists.

Unilateral injections of a D2 but not D1 agonist into the frontal cortex of rats produce a contralateral directional bias.

Unilateral manipulations of frontocortical dopamine have been found in previous studies to produce a directional bias in the circling behaviour of rats. Agonists produced contralateral circling and antagonists produced ipsilateral turning. To examine the role of dopamine receptor subtypes, the present studies investigated the ability of unilateral intrafrontal cortical microinjections of the D1 agonist, SKF 38393 or the D2 agonist, quinpirole to produce contralateral circling in rats. The antagonist, cis-flupenthixol was also tested and was expected to produce ipsilateral circling. In 3 separate experiments, rats received 7 50-min sessions in a circular arena separated by at least 48 hr. The first and final sessions were preceded by no injection, the second and sixth by saline [or the inactive trans isomer (2.5 micrograms) in the flupenthixol experiment] and the middle 3 sessions by doses of cis-flupenthixol (1, 10, 25 micrograms in 0.5 microliter), quinpirole (3, 6, 12 micrograms) or SKF 38393 (2, 4, 8 micrograms), the order being counterbalanced across rats. cis-Flupenthixol and quinpirole produced dose-dependent ipsi- and contralateral circling, respectively, whereas SKF 38393 was without significant effect. No reliable directional bias was seen in any no-injection, saline or trans-flupenthixol sessions. Results suggested that the D2 receptor may mediate the motor effects of frontal cortical dopamine.

Effect of a fleecy woollen underlay on sleep.

The folklore of ancient and modern cultures has recommended the use of wool as a bedding surface. In this article, the results of an experimental, repeated-measures study of the effect of a particular type of fleecy woollen sleeping surface on observed and reported sleep are reported. This woollen underlay significantly reduced the observed postural activity and favourably influenced subjective estimates of sleep, compared with the control conditions.

Characterization of feeding behavior induced by central injection of GRF.

The behavior resulting from injection of rat hypothalamic growth hormone-releasing factor (GRF) (0, 0.01, 0.1, 1.0 pmol) into the suprachiasmatic nucleus-medial preoptic area (SCN/MPOA) or the paraventricular nucleus (PVN) of the hypothalamus was examined. After injections of GRF, feeding and other behavioral responses of male Wistar rats were observed for 90 min. In the SCN/MPOA, GRF dose dependently increased food intake, increasing mean meal length at 0.1 pmol and increasing rate of eating with no effect on meal length at 1.0 pmol. Other behavioral measures were unaffected by GRF. There was no effect after injections into the PVN. These data are taken as confirmation that the SCN/MPOA region of the hypothalamus is important for the central stimulatory effects of GRF on feeding. The possibility that the PVN is involved in the expression of feeding derived from intra-SCN/MPOA GRF injections is discussed.

Diabetic retinopathy: examination practices and referral patterns of general practitioners.

OBJECTIVE: To investigate general practitioners' (GPs') examination and referral practices for diabetic retinopathy. METHODS: A questionnaire survey of a random stratified sample of 500 Victorian GPs. RESULTS: The response rate was 88%. 53% of GPs examined none or less than half of their patients with diabetes for diabetic retinopathy. Those who did examine for retinopathy rarely performed funduscopy through a dilated pupil and 65% reported that they never did. Only 37% had dilating drops in their surgery. Only 45% often or always tested visual acuity. 88% often or always referred patients at the recommended frequency to an ophthalmologist. CONCLUSIONS: Although most GPs do not perform dilated fundus examinations, they report referring their patients with diabetes for assessment by an ophthalmologist at an early stage to prevent vision loss. Referral chain breakdown may explain the discrepancy between GPs' reported referral rates and the lower rates of ophthalmic examination reported in the Melbourne Visual Impairment Project.

Genitourinary tract gas: imaging evaluation.

Gas-forming infections of the genitourinary tract may manifest as life-threatening conditions, often requiring aggressive medical and surgical management. Accurate interpretation of the radiologic studies is essential for early and accurate diagnosis of gas within the renal parenchyma or collecting system, bladder, uterus, and scrotum. Three distinct entities are associated with renal or perirenal gas: emphysematous pyelonephritis, emphysematous pyelitis, and gas-forming perirenal abscess. Gas in the bladder may occur secondary to emphysematous cystitis or a vesicoenteric fistula and must be differentiated from air introduced by means of instrumentation. Uterine gas usually indicates an underlying infection or a neoplasm. Gas in the scrotum is most commonly due to an infectious process or bowel herniation into the scrotal sac. Before institution of a specific therapeutic regimen, an effort should be made to establish the exact location of gas in the genitourinary tract. Plain radiography, including tomography, and ultrasonography are useful screening modalities. Although in some cases urography, barium enema studies, and other contrast material-enhanced studies enable a diagnosis to be made, in many patients computed tomography is the definitive diagnostic technique.