title: Gender affects rats' central nervous system histaminergic responses to dietary manipulation.
abstract: The histaminergic system (histamine and its H1-receptor) of the central nervous system has been implicated in control of food intake. The reported studies were designed to examine the effects of food restriction and very low (1%) protein diets on central nervous system H1-receptors in male and female rats. In a series of experiments, groups of rats were freely fed a 25% protein diet, a 1% protein diet, or fed the 25% protein diet at 4 g/100 g body weight for 14-20 d. When freely fed 25% protein diets, females had higher whole-brain H1-receptor binding than males on d 1 (female 122.36 +/- 4.53 and male 65.78 +/- 3.82 pmol/g protein; P < 0.001). Changing diets affected central H1-receptor binding in both males and females (P < 0.003). When rats were fed both restricted levels of food and 1% protein diets, the receptor binding of males increased by d 5 whereas that of females decreased by d 5 (P < 0.001). When fed 1% protein diets, females had decreased H1-receptor binding (98.4 +/- 2.38 pmol/g protein) and that in males increased to 119.81 +/- 5.09 pmol/g protein. After 15 d, females had eaten significantly more food than males: females 166 +/- 4.9 g, males 124 +/- 1.9 g (P< 0.0007). Males had a significantly greater weight loss than females: males -28.8 +/- 2.6 g, females -17.08 +/- 0.97 g (P < 0.0007). When fed restricted diets, females had decreased H1-receptor binding (93.81 +/- 5.58 pmol/g) whereas binding in males increased to 111.27 +/- 8.55 pmol/g. Preliminary saturation binding studies indicated that restricted food intake lowered receptor density (females consuming 25% protein: 715 +/- 30 pmol/g protein; female restricted: 467 +/- 28 pmol/g protein, P < 0.05), while 1% protein increased receptor sensitivity, i.e., lowered KD (males consuming 25% protein: 15.3 +/- 1.8 nmol; males fed low protein: 2.8 +/- 0.27 nmol). This study suggests that dietary manipulation affects central H1-receptor binding in a gender-specific manner, thereby modulating central histaminergic activity during food or protein deficit.
authors.affiliation: Department of Nutrition and Food Science, University of Kentucky, Lexington 40506-0054, USA.
authors.forename: L P
authors.initials: LP
authors.lastname: Mercer
authors.forename: D S
authors.initials: DS
authors.lastname: Kelley
authors.forename: H M
authors.initials: HM
authors.lastname: Bundrant
authors.forename: A U
authors.initials: AU
authors.lastname: Haq
authors.forename: L L
authors.initials: LL
authors.lastname: Humphries
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D005260:Female; D008297:Male; D051381:Rats; D011969:Receptors, Histamine H1 / Q000187:drug effects*; D012737:Sex Factors
chemical_list: D004044:Dietary Proteins; D011969:Receptors, Histamine H1