Sex Differences in the Drinking Response to Angiotensin II (AngII): Effect of Body Weight

Sex differences in fluid intake stimulated by angiotensin II (AngII) have been reported, but the direction of the differences is inconsistent. To resolve these discrepancies, we measured water intake by male and female rats given AngII. Males drank more than females, but when intake was normalized to body weight, the sex difference was reversed. Weight-matched males and females, however, had no difference in intake. Using a linear mixed model analysis, we found that intake was influenced by weight, sex, and AngII dose. We used linear regression to disentangle these effects further. Comparison of regression coefficients revealed sex and weight differences at high doses of AngII. Specifically, after 100ng AngII, weight was a predictor of intake in males, but not in females. Next, we tested for differences in AngII-induced intake in male and females allowed to drink both water and saline. Again, males drank more water than females, but females showed a stronger preference for saline. Drinking microstructure analysis suggested that these differences were mediated by postingestive signals and more bottle switches by the females. Finally, we probed for differences in the expression of components of the renin-angiotensin system in the brains of males and females and found sex differences in several genes in discrete brain regions. These results provide new information to help understand key sex differences in ingestive behaviors, and highlight the need for additional research to understand baseline sex differences, particularly in light of the new NIH initiative to balance sex in biomedical research

Saliva in ingestive behavior research: association with oral sensory perception and food intake

The present chapter aims to present what is known about the involvement of saliva in the way humans and animals perceive the sensory characteristics of diet. The chapter will start by presenting the biology of flavour perception and how it influences food acceptance and choice. We will then review the newest information on the participation of saliva in flavour and taste perception and the effect of pathologies in oral sensory perception

Induction of Salivary Proteins Modifies Measures of Both Orosensory and Postingestive Feedback during Exposure to a Tannic Acid Diet - Figure 4

<p>A–D: White bars represent feeding behaviors measured while animals were consuming the control diet; grey bars represent the same behaviors measured while animals were on the 3% tannic acid diet. The white bar labeled ‘C’ represents a 5-day average of behavioral measures on the control diet prior to exposure to the tannic acid diet. Food intake (A) and meal size (B) were decreased on the first 3 days of exposure to the tannic acid diet but returned to control levels by day 4. Meal number (C) was increased during the first 2 days of exposure to the tannic acid diet but returned to control-levels by day 3. Rate of feeding (D) was decreased throughout the entire exposure to the tannic acid diet buy this effect was most pronounced during the first 3 days.</p

Data depicted in the larger graphs are densitometry units normalized to average control (water replete) protein expressions (which are set to 1).

<p>The first bar (stippled) represents the average water replete expression of protein concentration, while all rats were fed the control diet. The data in the remainder of the bars were collected in the water-deprived condition. The white bar represents the average protein expression of all rats on the day of their first exposure to the brief-access taste test. The white bar with hash marks represents the saliva samples collected the day of the second exposure to the brief-access test by rats that were maintained on the control diet. The gray bar with hash marks represents the saliva samples collected the day of the second exposure to the brief-access test by rats that were maintained on the tannic acid diet between exposures. Statistical analyses were not preformed on these data. Total protein concentration was significantly altered by water deprivation making comparisons between samples unreliable. We have presented them only to illustrate the relative abundance of proteins across treatments. The inset graphs represent the change in densitometry units between the two test sessions (i.e. test 1 protein expression- test 2 protein expression) for the control group (white bar with hash marks) and experimental group (gray bar with hash marks). *Experimental group greater than the control group, P<0.05.</p

The sequence of rat protein cystatin S (Uniprot accession P19313).

<p>Bold regions indicate where tryptic peptides detected in proteomic analysis overlay the protein sequence.</p

The closed circles represent the average licking of the two test groups during their first exposure to the brief-access test (unconditioned licking does not differ between the groups at this time point p>0.05).

<p>The open circles represent the average licking during the second exposure to the brief-access test by rats that were maintained on the control diet. The open triangles represent the average licking during the second exposure to the brief-access test by rats that were maintained on the tannic acid diet between exposures. Lines represent curves fit to the average licking behavior. Rats with an increase in the salivary protein at 19/18.5 and 18 kDa bands show a right-ward shift in the licking response curve demonstrating that they found the tannic acid less aversive in the second exposure than the first exposure, while rats maintained on the control diet did not alter their licking behavior on the second exposure.</p