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Histaminergic regulation of seasonal metabolic rhythms in Siberian hamsters.

I'anson H, Jethwa PH, Warner A, Ebling FJ - Physiol. Behav. (2011)

Bottom Line: A ribosomal toxin (saporin) conjugated to orexin-B was infused into the ventral tuberomammillary region of the hypothalamus, since most histaminergic neurons express orexin receptors.This caused not only 75-80% loss of histaminergic neurons in the posterior hypothalamus, but also some loss of other orexin-receptor expressing cells e.g. MCH neurons.In summary, ablation of orexin-responsive cells in the posterior hypothalamus blocks the short-day induced decline in body weight by preventing seasonal hypophagia, evidence consistent with the hypothesis that central histaminergic mechanisms contribute to long-term regulation of body weight.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Washington and Lee University, Lexington, VA, USA.

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Study 1: VO2 in hamsters which had previously received bilateral infusions of saporin (SAP) or a saporin-orexin B conjugate (OXSAP) following saline vehicle treatment (SAL) or 30 mg/kg body weight thioperamide i.p. (THIO). Values are group mean ± SEM for the 2 h epoch following treatment, n = 7 SAP and n = 9 OXSAP. *P < 0.05 vs vehicle treatment.
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f0030: Study 1: VO2 in hamsters which had previously received bilateral infusions of saporin (SAP) or a saporin-orexin B conjugate (OXSAP) following saline vehicle treatment (SAL) or 30 mg/kg body weight thioperamide i.p. (THIO). Values are group mean ± SEM for the 2 h epoch following treatment, n = 7 SAP and n = 9 OXSAP. *P < 0.05 vs vehicle treatment.

Mentions: Intraperitoneal injection of thioperamide (30 mg/kg) produced a significant (P < 0.05) decrease in VO2 for a two hour period in SAP-treated hamsters but not in the hamsters that had been lesioned with OXSAP (Fig. 6). No parameters of food intake nor locomotor activity were significantly altered by thioperamide treatment in either group (data not shown). At necropsy 22 weeks after the initial OXSAP/SAP infusion, there were no significant differences between the groups in the wet weight of the intra-scapular brown adipose tissue, testes or epididymides (Table 1), however the epididymal fat pad weight was significantly lower in OXSAP-treated hamsters (Table 1), consistent with the lower overall body weight (Fig. 3, Table 1).


Histaminergic regulation of seasonal metabolic rhythms in Siberian hamsters.

I'anson H, Jethwa PH, Warner A, Ebling FJ - Physiol. Behav. (2011)

Study 1: VO2 in hamsters which had previously received bilateral infusions of saporin (SAP) or a saporin-orexin B conjugate (OXSAP) following saline vehicle treatment (SAL) or 30 mg/kg body weight thioperamide i.p. (THIO). Values are group mean ± SEM for the 2 h epoch following treatment, n = 7 SAP and n = 9 OXSAP. *P < 0.05 vs vehicle treatment.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3094761&req=5

f0030: Study 1: VO2 in hamsters which had previously received bilateral infusions of saporin (SAP) or a saporin-orexin B conjugate (OXSAP) following saline vehicle treatment (SAL) or 30 mg/kg body weight thioperamide i.p. (THIO). Values are group mean ± SEM for the 2 h epoch following treatment, n = 7 SAP and n = 9 OXSAP. *P < 0.05 vs vehicle treatment.
Mentions: Intraperitoneal injection of thioperamide (30 mg/kg) produced a significant (P < 0.05) decrease in VO2 for a two hour period in SAP-treated hamsters but not in the hamsters that had been lesioned with OXSAP (Fig. 6). No parameters of food intake nor locomotor activity were significantly altered by thioperamide treatment in either group (data not shown). At necropsy 22 weeks after the initial OXSAP/SAP infusion, there were no significant differences between the groups in the wet weight of the intra-scapular brown adipose tissue, testes or epididymides (Table 1), however the epididymal fat pad weight was significantly lower in OXSAP-treated hamsters (Table 1), consistent with the lower overall body weight (Fig. 3, Table 1).

Bottom Line: A ribosomal toxin (saporin) conjugated to orexin-B was infused into the ventral tuberomammillary region of the hypothalamus, since most histaminergic neurons express orexin receptors.This caused not only 75-80% loss of histaminergic neurons in the posterior hypothalamus, but also some loss of other orexin-receptor expressing cells e.g. MCH neurons.In summary, ablation of orexin-responsive cells in the posterior hypothalamus blocks the short-day induced decline in body weight by preventing seasonal hypophagia, evidence consistent with the hypothesis that central histaminergic mechanisms contribute to long-term regulation of body weight.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Washington and Lee University, Lexington, VA, USA.

Show MeSH
Related in: MedlinePlus