Korean J Urol.  2009 Apr;50(4):387-395.

Functional, Morphologic, and Molecular Biological Changes in the Bladder of OLETF Diabetic Rats according to Duration of Diabetes Mellitus

• Lee JH
• Suh HJ
• Cho HJ
• Lee YS
• Kim HW
• Kim SH
• Kim SW
• Hwang TK
• Lee SJ
• Lee JY

Abstract

PURPOSE
Our study was undertaken to investigate changes in the bladder according to duration of diabetes mellitus in the Otsuka Long Evans Tokushima Fatty (OLETF) rat model, which is similar to type 2 diabetes. MATERIALS AND METHODS: OLETF rats (n=14) and Long Evans Tokushima Otsuka (LETO, n=14) rats were used. LETO is a normal control of OLETF. The animals were assigned to 4 groups: L-40 group, LETO rats 40 weeks after birth (n=7); O-40 group, OLETF rats 40 weeks after birth (n=7); L-60 group, LETO rats 60 weeks after birth (n=7); and O-60 group, OLETF rats 60 weeks after birth (n=7). At 40 weeks or 60 weeks after birth, blood glucose, cystometry, bladder weight, detrusor contractility, and mRNA expression of nerve growth factor (NGF) were assessed. RESULTS: Cystometry showed that diabetic bladders had increased compliance compared with the control groups at 40 and 60 weeks, and the O-60 group had greater compliance than the O-40 group. Contractile responses to electrical stimulation, bethanecol (250microM), and ATP (10 mM) were decreased in the experimental groups compared with the control groups at 40 and 60 weeks, and the O-60 group had a lower contractile response than the O-40 group. The mRNA expression of NGF was decreased in the experimental groups compared with the control groups, and the O-60 group had lower expression than the O-40 group. Changes in NGF were identified through immunohistochemical staining. CONCLUSIONS: The degree of diabetic cystopathy in OLETF rats was changed by duration of type 2 diabetes mellitus. Our results showed that the changes in the bladder in type 2 diabetes mellitus can be identified through a new rat model.

Keyword

Type 2 diabetes mellitus; Neurogenic bladder; Nerve growth factor

MeSH Terms

Adenosine Triphosphate
Animals
Bethanechol
Blood Glucose
Compliance
Dextrans
Diabetes Mellitus
Diabetes Mellitus, Type 2
Drug Combinations
Electric Stimulation
Nerve Growth Factor
Parturition
Rats
Rats, Inbred OLETF
RNA, Messenger
Sodium Chloride
Urinary Bladder
Urinary Bladder, Neurogenic
Adenosine Triphosphate
Bethanechol
Blood Glucose
Dextrans
Drug Combinations
Nerve Growth Factor
RNA, Messenger
Sodium Chloride

Figure

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  Fig. 1 Comparison of blood glucose level in Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats. Blood glucose levels of the experimental groups were increased compared with the control groups at 40 and 60 weeks, and the O-60 group had a higher level than the O-40 group. The data are expressed as mean±SEM. L-40 group: LETO rats 40 weeks after birth (n=7), O-40 group: OLETF rats 40 weeks after birth (n=7), L-60 group: LETO rats 60 weeks after birth (n=7), O-60 group: OLETF rats 60 weeks after birth (n=7). a: significantly different from the control groups (p<0.05), b: significantly different from the O-40 group (p<0.05).

• 

  Fig. 2 Comparison of bladder compliance in Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats. The diabetic bladders had increased compliance compared with the control groups at 40 and 60 weeks, and the O-60 group had greater compliance than the O-40 group. The data are expressed as mean±SEM. L-40 group: LETO rats 40 weeks after birth (n=7), O-40 group: OLETF rats 40 weeks after birth (n=7), L-60 group: LETO rats 60 weeks after birth (n=7), O-60 group: OLETF rats 60 weeks after birth (n=7). a: significantly different from the control groups (p<0.05), b: significantly different from the O-40 group (p<0.05).

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  Fig. 3 Contractile response of the bladder muscle strip to 2, 8, 16, and 32 Hz electrical stimulation in Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats. Contractile response to electrical stimulation was decreased in the experimental groups compared with the control groups at 40 and 60 weeks, and the O-60 group had a lower contractile response than the O-40 group. The data are expressed as mean± SEM. L-40 group: LETO rats 40 weeks after birth (n=7), O-40 group: OLETF rats 40 weeks after birth (n=7), L-60 group: LETO rats 60 weeks after birth (n=7), O-60 group: OLETF rats 60 weeks after birth (n=7). a: significantly different from the control groups (p<0.05), b: significantly different from the O-40 group (p<0.05).

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  Fig. 4 Contractile response of bladder muscle strip to bethanechol (250µM) in Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats. The contractile response to bethanecol (250µM) was decreased in the experimental groups compared with the control groups at 40 and 60 weeks, and the O-60 group had a lower contractile response than the O-40 group. The data are expressed as mean±SEM. L-40 group: LETO rats 40 weeks after birth (n=7), O-40 group: OLETF rats 40 weeks after birth (n=7), L-60 group: LETO rats 60 weeks after birth (n=7), O-60 group: OLETF rats 60 weeks after birth (n=7). a: significantly different from the control groups (p<0.05), b: significantly different from the O-40 group (p<0.05).

• 

  Fig. 5 Contractile response of the bladder muscle strip to ATP (10 mM) in Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats. The contractile response to ATP (10 mM) was decreased in the experimental groups compared with the control groups at 40 and 60 weeks, and the O-60 group had a lower contractile response than the L-40 group. The data are expressed as mean±SEM. L-40 group: LETO rats 40 weeks after birth (n=7), O-40 group: OLETF rats 40 weeks after birth (n=7), L-60 group: LETO rats 60 weeks after birth (n=7), O-60 group: OLETF rats 60 weeks after birth (n=7). a: significantly different from the control groups (p<0.05), b: significantly different from the O-40 group (p<0.05).

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  Fig. 6 (A) Reverse transcript-polymerase chain reaction (RT-PCR) measurement of nerve growth factor (NGF) mRNA expression. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used for the internal control. M: 100 bp marker; lane 1: GAPDH (983 bp); lane 2: GAPDH+NGF (294 bp); lane 3: L-40 group; lane 4: O-40 group; lane 5: L-60 group; lane 6: O-60 group. (B) Results of densitometric scanning of NGF mRNA expression. The mRNA expression of NGF was decreased in the O-40 and O-60 groups compared with the control groups. The mRNA expression of NGF was lower in the O-60 group than in the O-40 group. The data are expressed as mean±SEM. L-40 group: Long Evans Tokushima Otsuka (LETO) rats 40 weeks after birth (n=7), O-40 group: Otsuka Long Evans Tokushima Fatty (OLETF) rats 40 weeks after birth (n=7), L-60 group: LETO rats 60 weeks after birth (n=7), O-60 group: OLETF rats 60 weeks after birth (n=7). a: significantly different from the control groups (p<0.05), b: significantly different from the O-40 group (p<0.05).

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  Fig. 7 Nerve growth factor (NGF) immunohistochemical staining of the bladder. NGF expression was decreased in the O-40 and O-60 groups compared with the control groups. NGF expression of the O-40 group was lower than in the O-60 group. (A) L-40 group (scale bar=25µm), (B) O-40 group (scale bar=25µm), (C) L-60 group (scale bar=25µm), (D) O-60 group (scale bar=25µm). L-40 group: Long Evans Tokushima Otsuka (LETO) rats 40 weeks after birth (n=7), O-40 group: Otsuka Long Evans Tokushima Fatty (OLETF) rats 40 weeks after birth (n=7), L-60 group: LETO rats 60 weeks after birth (n=7), O-60 group: OLETF rats 60 weeks after birth (n=7).

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