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High Fat Feeding inhibits the Hypothalamo‐Pituitary Gonadal (HPG) Axis and ovulation In Diet‐ Induced Obese Rats
Author(s) -
Balasubramanian Priya,
Jagannathan L.K.,
Gilbreath E.T.,
Subramanian M.,
Mohankumar P.S.,
Mohankumar S.M.J.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.627.5
Subject(s) - medicine , endocrinology , hypothalamus , ovulation , estrous cycle , leptin , luteinizing hormone , hypothalamic–pituitary–gonadal axis , follicular phase , chemistry , biology , hormone , obesity
Obesity is known to interfere with HPG functions, but the mechanisms involved are not clear. We hypothesized that a high fat (HF) diet would affect norepinephrine (NE) levels in the hypothalamus to impact luteinizing hormone (LH) release and ovulation in obesity. To test this, adult female diet‐induced obese (DIO) and diet resistant (DR) rats were fed chow or HF diet for 6 wks. Estrous cyclicity was monitored and hourly blood samples were collected from 1000–1900h for LH measurement on the day of proestrous. Animals were sacrificed on proestrous and plasma was processed for estradiol and leptin concentrations. Ovarian sections were subjected to morphological analysis. The medial preoptic area (MPA) and suprachiasmatic nucleus (SCN) of the hypothalamus that regulate LH secretion, were analyzed for NE levels. Leptin levels increased while estradiol levels were significantly reduced in the HF‐fed DIO group. NE levels (Mean±SE; pg/μg of protein) in the SCN dropped significantly in DIO HF (14.8±1.8) vs. chow‐fed DR rats (26.1±3.7; p<0.05). LH surge levels (ng/ml) in DIO HF was significantly lower compared to DR chow group (0.82±0.2 vs. 8.4±3.5; p<0.05). Ovaries from DIO HF animals had degenerating cystic follicles and no corpora lutea indicating anovulation. These results indicate that HF feeding inhibits the HPG axis in DIO rats possibly by increasing leptin levels to decrease ovarian estradiol synthesis. This leads to reduced NE levels in the hypothalamus causing suppression of the LH surge and anovulation.