Role of periaqueductal gray in the pressor response produced by central injections of angiotensin II.

The present studies were undertaken to determine the role of rostral periaqueductal gray (PAG) in mediating the pressor effect produced by intracerebroventricular (icv) injection of angiotensin II (ANG II, 200 ng). Two functionally and anatomically distinct sites were identified in rostral PAG: a dorsomedial site involved in the hemodynamic responses produced by electrical stimulation of the anteroventral third ventricle (AV3V) region and a ventromedial site required for the pressor response elicited by icv administration of ANG II. In Saffan-anesthetized rats, injection of lidocaine (LIDO, 4%) in dorsomedial PAG, but not in ventromedial PAG, significantly attenuated the decrease in hindquarter resistance (HQR) produced by electrical stimulation of the AV3V region, and the poststimulatory increase in mean arterial pressure (MAP) and HQR. The injection of LIDO in ventromedial PAG had no effect on the hemodynamic responses produced by electrical stimulation of the AV3V region in anesthetized rats but significantly attenuated the pressor response produced by icv administration of ANG II in conscious rats. The hypothesis that these two sites receive separate projections was addressed by microinjecting two retrogradely transported fluorescent dyes, Fluoro-Gold and Fast Blue. The anatomic findings suggest that separation of the pathways activated by electrical and chemical stimulation of the AV3V region occurs at the level of rostral PAG.

Measuring short-term dietary intake: development and testing of a 1-week food frequency questionnaire.

Measures typically used to assess short-term intake are 24-hour recalls or records of food intake. However, these methods require a large time commitment from both researchers and subjects. Our study sought to develop a more time-efficient method of assessing short-term intake by developing a 7-day food frequency questionnaire (7DFFQ). We modified Willett's 1-year food frequency questionnaire to assess intake for a 7-day period. Content validity has previously been exhibited in Willett's work. We assessed criterion validity by comparing the 7DFFQ with 24-hour recalls. Twenty-one female and 20 male college students were asked to recall their previous day's intake three times during a 1-week period. After the last recall, subjects completed a 7DFFQ covering the same week. Data were analyzed by comparing each recall and the mean of the three recalls with values obtained on the 7DFFQ. Analyses revealed high correlations between the mean of the three recalls and the 7DFFQ. Further analysis ranked subjects into quartiles for each nutrient on both measures. Most subjects changed either no quartiles or only one quartile for total energy and each nutrient. Test/retest reliability was assessed by administering the 7DFFQ to a group of women for two consecutive weeks and by administering the 7DFFQ to a group twice 3 hours apart. Pearson's r and intraclass correlations for the two administrations show moderately high reliability over the 1-week period and considerable improvement with the 3-hour administration. The 7DFFQ appears to meet several of the criteria for a measure of dietary intake.

Studies on the mechanism of the central antihypertensive effect of guanabenz and clonidine.

Mean arterial pressure and heart rate responses were measured following intracerebroventricular (i.c.v.) injections of guanabenz and clonidine in conscious intact, sinoaortic baroreceptor denervated (SAD) animals, and in SAD animals with anteroventral third ventricle (AV3V) or sham-AV3V lesions. These results suggest that in the conscious unrestrained rat: (1) the centrally-mediated depressor effect of guanabenz and clonidine is masked by intact baroreceptors; (2) the centrally mediated bradycardia is independent of baroreceptor function and (3) the integrity of the AV3V region is not required for expression of these central effects.